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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document seems to contain a disclaimer for pre-RFC5378 work, but was first submitted on or after 10 November 2008. The disclaimer is usually necessary only for documents that revise or obsolete older RFCs, and that take significant amounts of text from those RFCs. If you can contact all authors of the source material and they are willing to grant the BCP78 rights to the IETF Trust, you can and should remove the disclaimer. Otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (January 20, 2021) is 1191 days in the past. 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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'IMAP2' is mentioned on line 7236, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 7231, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 7221, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 7226, but not defined == Missing Reference: 'RFC-822' is mentioned on line 7240, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 7170, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 7159, but not defined == Missing Reference: 'RFC3503' is mentioned on line 7132, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 7199, but not defined == Missing Reference: 'SMTP' is mentioned on line 7180, but not defined == Missing Reference: 'RFC7888' is mentioned on line 7155, but not defined -- Looks like a reference, but probably isn't: '1' on line 906 == Missing Reference: 'IMAP-URL' is mentioned on line 7194, but not defined == Missing Reference: 'TLS' is mentioned on line 1219, but not defined == Missing Reference: 'CERT-555316' is mentioned on line 7127, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5851, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1780, but not defined == Missing Reference: 'RFC2193' is mentioned on line 7142, but not defined == Missing Reference: 'RFC3348' is mentioned on line 7530, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 7187, but not defined == Missing Reference: 'RFC3501' is mentioned on line 7217, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3309, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3381, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 7209, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 7164, but not defined == Missing Reference: 'HEADER' is mentioned on line 5869, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3961, but not defined == Missing Reference: 'UID' is mentioned on line 4384, but not defined == Missing Reference: 'RFC2087' is mentioned on line 7191, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 7204, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5853, but not defined == Missing Reference: 'RFC4422' is mentioned on line 6212, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6297, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 7244, but not defined == Missing Reference: 'RFCXXXX' is mentioned on line 6959, but not defined == Missing Reference: 'RFC5465' is mentioned on line 7151, but not defined == Missing Reference: 'RFC5256' is mentioned on line 7137, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 7262, but not defined == Missing Reference: 'RFC3516' is mentioned on line 7358, but not defined ** Downref: Normative reference to an Informational RFC: RFC 2152 (ref. 'UTF-7') ** Downref: Normative reference to an Informational RFC: RFC 2683 (ref. 'IMAP-IMPLEMENTATION') ** Downref: Normative reference to an Informational RFC: RFC 2180 (ref. 'IMAP-MULTIACCESS') Summary: 9 errors (**), 0 flaws (~~), 40 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Melnikov, Ed. 3 Internet-Draft Isode Ltd 4 Obsoletes: 3501 (if approved) B. Leiba, Ed. 5 Intended status: Standards Track Futurewei Technologies 6 Expires: July 24, 2021 January 20, 2021 8 Internet Message Access Protocol (IMAP) - Version 4rev2 9 draft-ietf-extra-imap4rev2-25 11 Abstract 13 The Internet Message Access Protocol, Version 4rev2 (IMAP4rev2) 14 allows a client to access and manipulate electronic mail messages on 15 a server. IMAP4rev2 permits manipulation of mailboxes (remote 16 message folders) in a way that is functionally equivalent to local 17 folders. IMAP4rev2 also provides the capability for an offline 18 client to resynchronize with the server. 20 IMAP4rev2 includes operations for creating, deleting, and renaming 21 mailboxes, checking for new messages, permanently removing messages, 22 setting and clearing flags, RFC 5322, RFC 2045 and RFC 2231 parsing, 23 searching, and selective fetching of message attributes, texts, and 24 portions thereof. Messages in IMAP4rev2 are accessed by the use of 25 numbers. These numbers are either message sequence numbers or unique 26 identifiers. 28 IMAP4rev2 does not specify a means of posting mail; this function is 29 handled by a mail submission protocol such as the one specified in 30 RFC 6409. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on July 24, 2021. 49 Copyright Notice 51 Copyright (c) 2021 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (https://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 This document may contain material from IETF Documents or IETF 65 Contributions published or made publicly available before November 66 10, 2008. The person(s) controlling the copyright in some of this 67 material may not have granted the IETF Trust the right to allow 68 modifications of such material outside the IETF Standards Process. 69 Without obtaining an adequate license from the person(s) controlling 70 the copyright in such materials, this document may not be modified 71 outside the IETF Standards Process, and derivative works of it may 72 not be created outside the IETF Standards Process, except to format 73 it for publication as an RFC or to translate it into languages other 74 than English. 76 Table of Contents 78 1. How to Read This Document . . . . . . . . . . . . . . . . . . 5 79 1.1. Organization of This Document . . . . . . . . . . . . . . 5 80 1.2. Conventions Used in This Document . . . . . . . . . . . . 5 81 1.3. Special Notes to Implementors . . . . . . . . . . . . . . 6 82 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 83 2.1. Link Level . . . . . . . . . . . . . . . . . . . . . . . 7 84 2.2. Commands and Responses . . . . . . . . . . . . . . . . . 7 85 2.2.1. Client Protocol Sender and Server Protocol Receiver . 7 86 2.2.2. Server Protocol Sender and Client Protocol Receiver . 8 87 2.3. Message Attributes . . . . . . . . . . . . . . . . . . . 9 88 2.3.1. Message Numbers . . . . . . . . . . . . . . . . . . . 9 89 2.3.2. Flags Message Attribute . . . . . . . . . . . . . . . 12 90 2.3.3. Internal Date Message Attribute . . . . . . . . . . . 14 91 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 14 92 2.3.5. Envelope Structure Message Attribute . . . . . . . . 14 93 2.3.6. Body Structure Message Attribute . . . . . . . . . . 14 94 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 14 95 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 14 96 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 15 97 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 15 98 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 15 99 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 15 100 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 17 101 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 17 102 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 17 103 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 17 104 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 17 105 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 18 106 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 19 107 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 108 5. Operational Considerations . . . . . . . . . . . . . . . . . 20 109 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 20 110 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 21 111 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 21 112 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 23 113 5.3. Response when no Command in Progress . . . . . . . . . . 23 114 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 23 115 5.5. Multiple Commands in Progress (Command Pipelining) . . . 24 116 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 117 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 26 118 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 26 119 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 27 120 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 121 6.2. Client Commands - Not Authenticated State . . . . . . . . 28 122 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 28 123 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 30 124 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 33 125 6.3. Client Commands - Authenticated State . . . . . . . . . . 33 126 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 34 127 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 36 128 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 38 129 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 39 130 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 40 131 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 42 132 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 44 133 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 45 134 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 45 135 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 63 136 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 68 137 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 69 138 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 72 139 6.4. Client Commands - Selected State . . . . . . . . . . . . 74 140 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 75 141 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 75 142 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 76 143 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 76 144 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 88 145 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 93 146 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 94 147 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 95 148 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 97 149 6.5. Client Commands - Experimental/Expansion . . . . . . . . 99 150 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 99 151 7.1. Server Responses - Generic Status Responses . . . . . . . 100 152 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 108 153 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 109 154 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 109 155 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 110 156 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 110 157 7.2. Server Responses - Server Status . . . . . . . . . . . . 111 158 7.2.1. ENABLED Response . . . . . . . . . . . . . . . . . . 111 159 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 111 160 7.3. Server Responses - Mailbox Status . . . . . . . . . . . . 112 161 7.3.1. LIST Response . . . . . . . . . . . . . . . . . . . . 112 162 7.3.2. NAMESPACE Response . . . . . . . . . . . . . . . . . 116 163 7.3.3. STATUS Response . . . . . . . . . . . . . . . . . . . 117 164 7.3.4. ESEARCH Response . . . . . . . . . . . . . . . . . . 117 165 7.3.5. FLAGS Response . . . . . . . . . . . . . . . . . . . 117 166 7.4. Server Responses - Mailbox Size . . . . . . . . . . . . . 118 167 7.4.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 118 168 7.5. Server Responses - Message Status . . . . . . . . . . . . 118 169 7.5.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 118 170 7.5.2. FETCH Response . . . . . . . . . . . . . . . . . . . 119 171 7.6. Server Responses - Command Continuation Request . . . . . 125 172 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 126 173 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 127 174 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 145 175 11. Security Considerations . . . . . . . . . . . . . . . . . . . 146 176 11.1. TLS related Security Considerations . . . . . . . . . . 146 177 11.2. STARTTLS command versa use of Implicit TLS port . . . . 146 178 11.3. Client handling of unsolicited responses not suitable 179 for the current connection state . . . . . . . . . . . . 147 180 11.4. COPYUID and APPENDUID response codes . . . . . . . . . . 147 181 11.5. LIST command and Other Users' namespace . . . . . . . . 148 182 11.6. Other Security Considerations . . . . . . . . . . . . . 148 183 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 149 184 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 149 185 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 149 186 12.3. LIST Selection Options, LIST Return Options, LIST 187 extended data items . . . . . . . . . . . . . . . . . . 150 188 12.4. IMAP Mailbox Name Attributes and IMAP Response Codes . . 150 189 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 150 190 13.1. Normative References . . . . . . . . . . . . . . . . . . 150 191 13.2. Informative References (related protocols) . . . . . . . 153 192 13.3. Informative References (historical aspects of IMAP and 193 related protocols) . . . . . . . . . . . . . . . . . . . 155 194 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 156 195 A.1. Mailbox International Naming Convention for compatibility 196 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 157 197 Appendix B. Backward compatibility with BINARY extension . . . . 158 198 Appendix C. Backward compatibility with LIST-EXTENDED extension 158 199 Appendix D. 63 bit body part and message sizes . . . . . . . . . 159 200 Appendix E. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 159 201 Appendix F. Other Recommended IMAP Extensions . . . . . . . . . 161 202 Appendix G. Acknowledgement . . . . . . . . . . . . . . . . . . 161 203 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 204 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 167 206 1. How to Read This Document 208 1.1. Organization of This Document 210 This document is written from the point of view of the implementor of 211 an IMAP4rev2 client or server. Beyond the protocol overview in 212 section 2, it is not optimized for someone trying to understand the 213 operation of the protocol. The material in sections 3 through 5 214 provides the general context and definitions with which IMAP4rev2 215 operates. 217 Sections 6, 7, and 9 describe the IMAP commands, responses, and 218 syntax, respectively. The relationships among these are such that it 219 is almost impossible to understand any of them separately. In 220 particular, do not attempt to deduce command syntax from the command 221 section alone; instead refer to the Formal Syntax (Section 9). 223 1.2. Conventions Used in This Document 225 "Conventions" are basic principles or procedures. Document 226 conventions are noted in this section. 228 In examples, "C:" and "S:" indicate lines sent by the client and 229 server respectively. Note that each line includes the terminating 230 CRLF. 232 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 233 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 234 "OPTIONAL" in this document are to be interpreted as described in BCP 235 14 [RFC2119] [RFC8174] when, and only when, they appear in all 236 capitals, as shown here. 238 The word "can" (not "may") is used to refer to a possible 239 circumstance or situation, as opposed to an optional facility of the 240 protocol. 242 "User" is used to refer to a human user, whereas "client" refers to 243 the software being run by the user. 245 "Connection" refers to the entire sequence of client/server 246 interaction from the initial establishment of the network connection 247 until its termination. 249 "Session" refers to the sequence of client/server interaction from 250 the time that a mailbox is selected (SELECT or EXAMINE command) until 251 the time that selection ends (SELECT or EXAMINE of another mailbox, 252 CLOSE command, UNSELECT command, or connection termination). 254 The term "Implicit TLS" refers to the automatic negotiation of TLS 255 whenever a TCP connection is made on a particular TCP port that is 256 used exclusively by that server for TLS connections. The term 257 "Implicit TLS" is intended to contrast with the use of STARTTLS 258 command in IMAP that is used by the client and the server to 259 explicitly negotiate TLS on an established cleartext TCP connection. 261 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 262 unless otherwise specified. Other character sets are indicated using 263 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 264 CHARSETs have important additional semantics in addition to defining 265 character set; refer to these documents for more detail. 267 There are several protocol conventions in IMAP. These refer to 268 aspects of the specification which are not strictly part of the IMAP 269 protocol, but reflect generally-accepted practice. Implementations 270 need to be aware of these conventions, and avoid conflicts whether or 271 not they implement the convention. For example, "&" may not be used 272 as a hierarchy delimiter since it conflicts with the Mailbox 273 International Naming Convention, and other uses of "&" in mailbox 274 names are impacted as well. 276 1.3. Special Notes to Implementors 278 Implementors of the IMAP protocol are strongly encouraged to read the 279 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 280 conjunction with this document, to help understand the intricacies of 281 this protocol and how best to build an interoperable product. 283 IMAP4rev2 is designed to be upwards compatible from the IMAP4rev1, 284 the [IMAP2] and unpublished IMAP2bis protocols. IMAP4rev2 is largely 285 compatible with the IMAP4rev1 protocol described in RFC 3501 and the 286 IMAP4 protocol described in RFC 1730; the exception being in certain 287 facilities added in RFC 1730 and RFC 3501 that proved problematic and 288 were subsequently removed or replaced by better alternatives. In the 289 course of the evolution of IMAP4rev2, some aspects in the earlier 290 protocols have become obsolete. Obsolete commands, responses, and 291 data formats which an IMAP4rev2 implementation can encounter when 292 used with an earlier implementation are described in Appendix E, 293 Appendix A and [IMAP-OBSOLETE]. IMAP4rev2 supports 63bit body part 294 and message sizes. IMAP4rev2 compatibility with BINARY and LIST- 295 EXTENDED IMAP extensions are described in Appendix B and Appendix C 296 respectively. 298 Other compatibility issues with IMAP2bis, the most common variant of 299 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 300 discussion of compatibility issues with rare (and presumed extinct) 301 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 302 primarily of historical interest. 304 IMAP was originally developed for the older [RFC-822] standard, and 305 as a consequence several fetch items in IMAP incorporate "RFC822" in 306 their name. In all cases, "RFC822" should be interpreted as a 307 reference to the updated [RFC-5322] standard. 309 2. Protocol Overview 311 2.1. Link Level 313 The IMAP4rev2 protocol assumes a reliable data stream such as that 314 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 315 port 143 or port 993 (IMAP-over-TLS). 317 2.2. Commands and Responses 319 An IMAP4rev2 connection consists of the establishment of a client/ 320 server network connection, an initial greeting from the server, and 321 client/server interactions. These client/server interactions consist 322 of a client command, server data, and a server completion result 323 response. 325 All interactions transmitted by client and server are in the form of 326 lines, that is, strings that end with a CRLF. The protocol receiver 327 of an IMAP4rev2 client or server is either reading a line, or is 328 reading a sequence of octets with a known count followed by a line. 330 2.2.1. Client Protocol Sender and Server Protocol Receiver 332 The client command begins an operation. Each client command is 333 prefixed with an identifier (typically a short alphanumeric string, 334 e.g., A0001, A0002, etc.) called a "tag". A different tag is 335 generated by the client for each command. More formally: the client 336 SHOULD generate a unique tag for every command, but a server MUST 337 accept tag reuse. 339 Clients MUST follow the syntax outlined in this specification 340 strictly. It is a syntax error to send a command with missing or 341 extraneous spaces or arguments. 343 There are two cases in which a line from the client does not 344 represent a complete command. In one case, a command argument is 345 quoted with an octet count (see the description of literal in 346 Section 4.3); in the other case, the command arguments require server 347 feedback (see the AUTHENTICATE command in Section 6.2.2). In either 348 case, the server sends a command continuation request response if it 349 is ready for the octets (if appropriate) and the remainder of the 350 command. This response is prefixed with the token "+". 352 Note: If instead, the server detected an error in the command, it 353 sends a BAD completion response with a tag matching the command 354 (as described below) to reject the command and prevent the client 355 from sending any more of the command. 357 It is also possible for the server to send a completion response 358 for some other command (if multiple commands are in progress), or 359 untagged data. In either case, the command continuation request 360 is still pending; the client takes the appropriate action for the 361 response, and reads another response from the server. In all 362 cases, the client MUST send a complete command (including 363 receiving all command continuation request responses and command 364 continuations for the command) before initiating a new command. 366 The protocol receiver of an IMAP4rev2 server reads a command line 367 from the client, parses the command and its arguments, and transmits 368 server data and a server command completion result response. 370 2.2.2. Server Protocol Sender and Client Protocol Receiver 372 Data transmitted by the server to the client and status responses 373 that do not indicate command completion are prefixed with the token 374 "*", and are called untagged responses. 376 Server data MAY be sent as a result of a client command, or MAY be 377 sent unilaterally by the server. There is no syntactic difference 378 between server data that resulted from a specific command and server 379 data that were sent unilaterally. 381 The server completion result response indicates the success or 382 failure of the operation. It is tagged with the same tag as the 383 client command which began the operation. Thus, if more than one 384 command is in progress, the tag in a server completion response 385 identifies the command to which the response applies. There are 386 three possible server completion responses: OK (indicating success), 387 NO (indicating failure), or BAD (indicating a protocol error such as 388 unrecognized command or command syntax error). 390 Servers SHOULD enforce the syntax outlined in this specification 391 strictly. Any client command with a protocol syntax error, including 392 (but not limited to) missing or extraneous spaces or arguments, 393 SHOULD be rejected, and the client given a BAD server completion 394 response. 396 The protocol receiver of an IMAP4rev2 client reads a response line 397 from the server. It then takes action on the response based upon the 398 first token of the response, which can be a tag, a "*", or a "+". 400 A client MUST be prepared to accept any server response at all times. 401 This includes server data that was not requested. Server data SHOULD 402 be remembered (cached), so that the client can reference its 403 remembered copy rather than sending a command to the server to 404 request the data. In the case of certain server data, the data MUST 405 be remembered, as specified elsewhere in this document. 407 This topic is discussed in greater detail in the Server Responses 408 section. 410 2.3. Message Attributes 412 In addition to message text, each message has several attributes 413 associated with it. These attributes can be retrieved individually 414 or in conjunction with other attributes or message texts. 416 2.3.1. Message Numbers 418 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 419 identifier or the message sequence number. 421 2.3.1.1. Unique Identifier (UID) Message Attribute 423 A UID is an unsigned non-zero 32-bit value assigned to each message, 424 which when used with the unique identifier validity value (see below) 425 forms a 64-bit value that MUST NOT refer to any other message in the 426 mailbox or any subsequent mailbox with the same name forever. Unique 427 identifiers are assigned in a strictly ascending fashion in the 428 mailbox; as each message is added to the mailbox it is assigned a 429 higher UID than the message(s) which were added previously. Unlike 430 message sequence numbers, unique identifiers are not necessarily 431 contiguous. 433 The unique identifier of a message MUST NOT change during the 434 session, and SHOULD NOT change between sessions. Any change of 435 unique identifiers between sessions MUST be detectable using the 436 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 437 are required for a client to resynchronize its state from a previous 438 session with the server (e.g., disconnected or offline access clients 439 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 441 Associated with every mailbox are two 32-bit unsigned non-zero values 442 which aid in unique identifier handling: the next unique identifier 443 value (UIDNEXT) and the unique identifier validity value 444 (UIDVALIDITY). 446 The next unique identifier value is the predicted value that will be 447 assigned to a new message in the mailbox. Unless the unique 448 identifier validity also changes (see below), the next unique 449 identifier value MUST have the following two characteristics. First, 450 the next unique identifier value MUST NOT change unless new messages 451 are added to the mailbox; and second, the next unique identifier 452 value MUST change whenever new messages are added to the mailbox, 453 even if those new messages are subsequently expunged. 455 Note: The next unique identifier value is intended to provide a 456 means for a client to determine whether any messages have been 457 delivered to the mailbox since the previous time it checked this 458 value. It is not intended to provide any guarantee that any 459 message will have this unique identifier. A client can only 460 assume, at the time that it obtains the next unique identifier 461 value, that messages arriving after that time will have a UID 462 greater than or equal to that value. 464 The unique identifier validity value is sent in a UIDVALIDITY 465 response code in an OK untagged response at mailbox selection time. 466 If unique identifiers from an earlier session fail to persist in this 467 session, the unique identifier validity value MUST be greater than 468 the one used in the earlier session. A good UIDVALIDITY value to use 469 is a 32-bit representation of the current date/time when the value is 470 assigned: this ensures that the value is unique and always increases. 471 Another possible alternative is a global counter that gets 472 incremented every time a mailbox is created. 474 Note: Ideally, unique identifiers SHOULD persist at all times. 475 Although this specification recognizes that failure to persist can 476 be unavoidable in certain server environments, it strongly 477 encourages message store implementation techniques that avoid this 478 problem. For example: 480 1. Unique identifiers MUST be strictly ascending in the mailbox 481 at all times. If the physical message store is re-ordered by 482 a non-IMAP agent, this requires that the unique identifiers in 483 the mailbox be regenerated, since the former unique 484 identifiers are no longer strictly ascending as a result of 485 the re-ordering. 487 2. If the message store has no mechanism to store unique 488 identifiers, it must regenerate unique identifiers at each 489 session, and each session must have a unique UIDVALIDITY 490 value. 492 3. If the mailbox is deleted/renamed and a new mailbox with the 493 same name is created at a later date, the server must either 494 keep track of unique identifiers from the previous instance of 495 the mailbox, or it must assign a new UIDVALIDITY value to the 496 new instance of the mailbox. 498 4. The combination of mailbox name, UIDVALIDITY, and UID must 499 refer to a single immutable (or expunged) message on that 500 server forever. In particular, the internal date, [RFC-5322] 501 size, envelope, body structure, and message texts (all 502 BODY[...] fetch data items) must never change. This does not 503 include message numbers, nor does it include attributes that 504 can be set by a STORE command (e.g., FLAGS). When a message 505 is expunged, its UID MUST NOT be reused under the same 506 UIDVALIDITY value. 508 2.3.1.2. Message Sequence Number Message Attribute 510 A Message Sequence Number is a relative position from 1 to the number 511 of messages in the mailbox. This position MUST be ordered by 512 ascending unique identifier. As each new message is added, it is 513 assigned a message sequence number that is 1 higher than the number 514 of messages in the mailbox before that new message was added. 516 Message sequence numbers can be reassigned during the session. For 517 example, when a message is permanently removed (expunged) from the 518 mailbox, the message sequence number for all subsequent messages is 519 decremented. The number of messages in the mailbox is also 520 decremented. Similarly, a new message can be assigned a message 521 sequence number that was once held by some other message prior to an 522 expunge. 524 In addition to accessing messages by relative position in the 525 mailbox, message sequence numbers can be used in mathematical 526 calculations. For example, if an untagged "11 EXISTS" is received, 527 and previously an untagged "8 EXISTS" was received, three new 528 messages have arrived with message sequence numbers of 9, 10, and 11. 529 Another example, if message 287 in a 523 message mailbox has UID 530 12345, there are exactly 286 messages which have lesser UIDs and 236 531 messages which have greater UIDs. 533 2.3.2. Flags Message Attribute 535 A message has associated with it a list of zero or more named tokens, 536 known as "flags". A flag is set by its addition to this list, and is 537 cleared by its removal. There are two types of flags in IMAP4rev2: 538 system flags, and keywords. A flag of either type can also be 539 permanent or session-only. 541 A system flag is a flag name that is pre-defined in this 542 specification and begins with "\". Certain system flags (\Deleted 543 and \Seen) have special semantics described elsewhere in this 544 document. The currently-defined system flags are: 546 \Seen Message has been read 548 \Answered Message has been answered 550 \Flagged Message is "flagged" for urgent/special attention 552 \Deleted Message is "deleted" for removal by later EXPUNGE 554 \Draft Message has not completed composition (marked as a draft). 556 \Recent This flag was in use in IMAP4rev1 and is now deprecated. 558 A keyword is defined by the server implementation. Keywords do not 559 begin with "\". Servers MAY permit the client to define new keywords 560 in the mailbox (see the description of the PERMANENTFLAGS response 561 code for more information). Some keywords that start with "$" are 562 also defined in this specification. 564 This document defines several keywords that were not originally 565 defined in RFC 3501, but which were found to be useful by client 566 implementations. These keywords SHOULD be supported (i.e. allowed in 567 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 568 server implementations: 570 $Forwarded Message has been forwarded to another email address, 571 embedded within or attached to a new message. An email client 572 sets this keyword when it successfully forwards the message to 573 another email address. Typical usage of this keyword is to show a 574 different (or additional) icon for a message that has been 575 forwarded. Once set, the flag SHOULD NOT be cleared. 577 $MDNSent Message Disposition Notification [RFC8098] was generated 578 and sent for this message. See [RFC3503] for more details on how 579 this keyword is used. 581 $Junk The user (or a delivery agent on behalf of the user) may 582 choose to mark a message as definitely containing junk ($Junk; see 583 also the related keyword $NotJunk). The $Junk keyword can be used 584 to mark (and potentially move/delete messages later), group or 585 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 586 information. 588 $NotJunk The user (or a delivery agent on behalf of the user) may 589 choose to mark a message as definitely not containing junk 590 ($NotJunk; see also the related keyword $Junk). The $NotJunk 591 keyword can be used to mark, group or show messages that the user 592 wants to see. See [IMAP-KEYWORDS-REG] for more information. 594 $Phishing The $Phishing keyword can be used by a delivery agent to 595 mark a message as highly likely to be a phishing email. An email 596 that's determined to be a phishing email by the delivery agent 597 should also be considered a junk email and have the appropriate 598 junk filtering applied, including setting the $Junk flag and 599 placing in the \Junk special-use mailbox (see Section 7.3.1) if 600 available. 601 If both the $Phishing flag and the $Junk flag are set, the user 602 agent should display an additional warning message to the user. 603 Additionally the user agent may display a warning when clicking on 604 any hyperlinks within the message. 605 The requirement for both $Phishing and $Junk to be set before a 606 user agent displays a warning is for better backwards 607 compatibility with existing clients that understand the $Junk flag 608 but not the $Phishing flag. This so that when an unextended 609 client removes the $Junk flag, an extended client will also show 610 the correct state. See [IMAP-KEYWORDS-REG] for more information. 612 $Junk and $NotJunk are mutually exclusive. If more than one of them 613 is set for a message, the client MUST treat this as if none of them 614 is set and SHOULD unset both of them on the IMAP server. 616 Other registered keywords can be found in the "IMAP and JMAP 617 Keywords" registry [IMAP-KEYWORDS-REG]. New keywords SHOULD be 618 registered in this registry using the procedure specified in 619 [RFC5788]. 621 A flag can be permanent or session-only on a per-flag basis. 622 Permanent flags are those which the client can add or remove from the 623 message flags permanently; that is, concurrent and subsequent 624 sessions will see any change in permanent flags. Changes to session 625 flags are valid only in that session. 627 2.3.3. Internal Date Message Attribute 629 An Internal Date message attribute is the internal date and time of 630 the message on the server. This is not the date and time in the 631 [RFC-5322] header, but rather a date and time which reflects when the 632 message was received. In the case of messages delivered via [SMTP], 633 this is the date and time of final delivery of the message as defined 634 by [SMTP]. In the case of messages delivered by the IMAP4rev2 COPY 635 or MOVE command, this SHOULD be the internal date and time of the 636 source message. In the case of messages delivered by the IMAP4rev2 637 APPEND command, this SHOULD be the date and time as specified in the 638 APPEND command description. All other cases are implementation 639 defined. 641 2.3.4. [RFC-5322] Size Message Attribute 643 An RFC 5322 size is the number of octets in the message, as expressed 644 in [RFC-5322] format. 646 2.3.5. Envelope Structure Message Attribute 648 An Envelope Structure is a parsed representation of the [RFC-5322] 649 header of the message. Note that the IMAP Envelope structure is not 650 the same as an [SMTP] envelope. 652 2.3.6. Body Structure Message Attribute 654 A Body Structure is a parsed representation of the [MIME-IMB] body 655 structure information of the message. 657 2.4. Message Texts 659 In addition to being able to fetch the full [RFC-5322] text of a 660 message, IMAP4rev2 permits the fetching of portions of the full 661 message text. Specifically, it is possible to fetch the [RFC-5322] 662 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 663 [MIME-IMB] header. 665 3. State and Flow Diagram 667 Once the connection between client and server is established, an 668 IMAP4rev2 connection is in one of four states. The initial state is 669 identified in the server greeting. Most commands are only valid in 670 certain states. It is a protocol error for the client to attempt a 671 command while the connection is in an inappropriate state, and the 672 server will respond with a BAD or NO (depending upon server 673 implementation) command completion result. 675 3.1. Not Authenticated State 677 In the not authenticated state, the client MUST supply authentication 678 credentials before most commands will be permitted. This state is 679 entered when a connection starts unless the connection has been pre- 680 authenticated. 682 3.2. Authenticated State 684 In the authenticated state, the client is authenticated and MUST 685 select a mailbox to access before commands that affect messages will 686 be permitted. This state is entered when a pre-authenticated 687 connection starts, when acceptable authentication credentials have 688 been provided, after an error in selecting a mailbox, or after a 689 successful CLOSE command. 691 3.3. Selected State 693 In a selected state, a mailbox has been selected to access. This 694 state is entered when a mailbox has been successfully selected. 696 3.4. Logout State 698 In the logout state, the connection is being terminated. This state 699 can be entered as a result of a client request (via the LOGOUT 700 command) or by unilateral action on the part of either the client or 701 server. 703 If the client requests the logout state, the server MUST send an 704 untagged BYE response and a tagged OK response to the LOGOUT command 705 before the server closes the connection; and the client MUST read the 706 tagged OK response to the LOGOUT command before the client closes the 707 connection. 709 A server SHOULD NOT unilaterally close the connection without sending 710 an untagged BYE response that contains the reason for having done so. 711 A client SHOULD NOT unilaterally close the connection, and instead 712 SHOULD issue a LOGOUT command. If the server detects that the client 713 has unilaterally closed the connection, the server MAY omit the 714 untagged BYE response and simply close its connection. 716 +----------------------+ 717 |connection established| 718 +----------------------+ 719 || 720 \/ 721 +--------------------------------------+ 722 | server greeting | 723 +--------------------------------------+ 724 || (1) || (2) || (3) 725 \/ || || 726 +-----------------+ || || 727 |Not Authenticated| || || 728 +-----------------+ || || 729 || (7) || (4) || || 730 || \/ \/ || 731 || +----------------+ || 732 || | Authenticated |<=++ || 733 || +----------------+ || || 734 || || (7) || (5) || (6) || 735 || || \/ || || 736 || || +--------+ || || 737 || || |Selected|==++ || 738 || || +--------+ || 739 || || || (7) || 740 \/ \/ \/ \/ 741 +--------------------------------------+ 742 | Logout | 743 +--------------------------------------+ 744 || 745 \/ 746 +-------------------------------+ 747 |both sides close the connection| 748 +-------------------------------+ 750 (1) connection without pre-authentication (OK greeting) 751 (2) pre-authenticated connection (PREAUTH greeting) 752 (3) rejected connection (BYE greeting) 753 (4) successful LOGIN or AUTHENTICATE command 754 (5) successful SELECT or EXAMINE command 755 (6) CLOSE command, unsolicited CLOSED response code or 756 failed SELECT or EXAMINE command 757 (7) LOGOUT command, server shutdown, or connection closed 759 4. Data Formats 761 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 762 be in one of several forms: atom, number, string, parenthesized list, 763 or NIL. Note that a particular data item may take more than one 764 form; for example, a data item defined as using "astring" syntax may 765 be either an atom or a string. 767 4.1. Atom 769 An atom consists of one or more non-special characters. 771 4.1.1. Sequence set and UID set 773 A set of messages can be referenced by a sequence set containing 774 either message sequence numbers or unique identifiers. See Section 9 775 for details. Sequence sets can contain ranges (e.g. "5:50"), an 776 enumeration of specific message/UID numbers, a special symbol "*", or 777 a combination of the above. 779 A "UID set" is similar to the sequence set of unique identifiers; 780 however, the "*" value for a sequence number is not permitted. 782 4.2. Number 784 A number consists of one or more digit characters, and represents a 785 numeric value. 787 4.3. String 789 A string is in one of three forms: synchonizing literal, non- 790 synchronizing literal or quoted string. The synchronizing literal 791 form is the general form of string. The non-synchronizing literal 792 form is also the general form, but has length limitation. The quoted 793 string form is an alternative that avoids the overhead of processing 794 a literal at the cost of limitations of characters which may be used. 796 When the distinction between synchronizing and non-synchronizing 797 literals is not important, this document just uses the term 798 "literal". 800 A synchronizing literal is a sequence of zero or more octets 801 (including CR and LF), prefix-quoted with an octet count in the form 802 of an open brace ("{"), the number of octets, close brace ("}"), and 803 CRLF. In the case of synchronizing literals transmitted from server 804 to client, the CRLF is immediately followed by the octet data. In 805 the case of synchronizing literals transmitted from client to server, 806 the client MUST wait to receive a command continuation request 807 (described later in this document) before sending the octet data (and 808 the remainder of the command). 810 The non-synchronizing literal is an alternative form of synchronizing 811 literal, and it may appear in communication from client to server 812 instead of the synchonizing form of literal. The non-synchronizing 813 literal form MUST NOT be sent from server to client. The non- 814 synchronizing literal is distinguished from the synchronizing literal 815 by having a plus ("+") between the octet count and the closing brace 816 ("}"). The server does not generate a command continuation request 817 in response to a non-synchronizing literal, and clients are not 818 required to wait before sending the octets of a non- synchronizing 819 literal. Non-synchronizing literals MUST NOT be larger than 4096 820 octets. Any literal larger than 4096 bytes MUST be sent as a 821 synchronizing literal. (Non-synchronizing literals defined in this 822 document are the same as non-synchronizing literals defined by the 823 LITERAL- extension from [RFC7888]. See that document for details on 824 how to handle invalid non-synchronizing literals longer than 4096 825 octets and for interaction with other IMAP extensions.) 827 A quoted string is a sequence of zero or more Unicode characters, 828 excluding CR and LF, encoded in UTF-8, with double quote (<">) 829 characters at each end. 831 The empty string is represented as "" (a quoted string with zero 832 characters between double quotes), as {0} followed by CRLF (a 833 synchronizing literal with an octet count of 0) or as {0+} followed 834 by CRLF (a non-synchronizing literal with an octet count of 0). 836 Note: Even if the octet count is 0, a client transmitting a 837 synchronizing literal MUST wait to receive a command continuation 838 request. 840 4.3.1. 8-bit and Binary Strings 842 8-bit textual and binary mail is supported through the use of a 843 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 844 transmit 8-bit or multi-octet characters in literals, but SHOULD do 845 so only when the [CHARSET] is identified. 847 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 848 identified charset for header-field values with 8-bit content is 849 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 850 transmit [UTF-8] text in quoted-strings as long as the string does 851 not contain NUL, CR, or LF. This differs from IMAP4rev1 852 implementations. 854 Although a BINARY content transfer encoding is defined, unencoded 855 binary strings are not permitted, unless returned in a in 856 response to BINARY.PEEK[]<> or 857 BINARY[]<> FETCH data item. A "binary 858 string" is any string with NUL characters. A string with an 859 excessive amount of CTL characters MAY also be considered to be 860 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 861 FETCH, client and server implementations MUST encode binary data into 862 a textual form, such as BASE64, before transmitting the data. 864 4.4. Parenthesized List 866 Data structures are represented as a "parenthesized list"; a sequence 867 of data items, delimited by space, and bounded at each end by 868 parentheses. A parenthesized list can contain other parenthesized 869 lists, using multiple levels of parentheses to indicate nesting. 871 The empty list is represented as () -- a parenthesized list with no 872 members. 874 4.5. NIL 876 The special form "NIL" represents the non-existence of a particular 877 data item that is represented as a string or parenthesized list, as 878 distinct from the empty string "" or the empty parenthesized list (). 880 Note: NIL is never used for any data item which takes the form of 881 an atom. For example, a mailbox name of "NIL" is a mailbox named 882 NIL as opposed to a non-existent mailbox name. This is because 883 mailbox uses "astring" syntax which is an atom or a string. 884 Conversely, an addr-name of NIL is a non-existent personal name, 885 because addr-name uses "nstring" syntax which is NIL or a string, 886 but never an atom. 888 Examples: 890 The following LIST response: 892 * LIST () "/" NIL 894 is equivalent to: 896 * LIST () "/" "NIL" 898 as LIST response ABNF is using "astring" for mailbox name. 900 However, the following response 902 * FETCH 1 (BODY[1] NIL) 904 is not equivalent to: 906 * FETCH 1 (BODY[1] "NIL") 908 The former means absence of the body part, while the latter 909 means that it contains literal sequence of characters "NIL". 911 5. Operational Considerations 913 The following rules are listed here to ensure that all IMAP4rev2 914 implementations interoperate properly. 916 5.1. Mailbox Naming 918 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 919 (this differs from IMAP4rev1). Client implementations MAY attempt to 920 create Net-Unicode mailbox names, and MUST interpret any 8-bit 921 mailbox names returned by LIST as [NET-UNICODE]. Server 922 implementations MUST prohibit the creation of 8-bit mailbox names 923 that do not comply with Net-Unicode. However, servers MAY accept a 924 de-normalized UTF-8 mailbox name and convert it to Unicode 925 normalization form "NFC" (as per Net-Unicode requirements) prior to 926 mailbox creation. Servers that choose to accept such de-normalized 927 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 928 mailbox name parameter. In particular SELECT must open the 929 same mailbox that was successfully created with CREATE , even 930 if is a de-normalized UTF-8 mailbox name. 932 The case-insensitive mailbox name INBOX is a special name reserved to 933 mean "the primary mailbox for this user on this server". (Note that 934 this special name may not exist on some servers for some users, for 935 example if the user has no access to personal namespace.) The 936 interpretation of all other names is implementation-dependent. 938 In particular, this specification takes no position on case 939 sensitivity in non-INBOX mailbox names. Some server implementations 940 are fully case-sensitive in ASCII range; others preserve case of a 941 newly-created name but otherwise are case-insensitive; and yet others 942 coerce names to a particular case. Client implementations must be 943 able to interact with any of these. 945 There are certain client considerations when creating a new mailbox 946 name: 948 1. Any character which is one of the atom-specials (see the Formal 949 Syntax in Section 9) will require that the mailbox name be 950 represented as a quoted string or literal. 952 2. CTL and other non-graphic characters are difficult to represent 953 in a user interface and are best avoided. Servers MAY refuse to 954 create mailbox names containing Unicode CTL characters. 956 3. Although the list-wildcard characters ("%" and "*") are valid in 957 a mailbox name, it is difficult to use such mailbox names with 958 the LIST command due to the conflict with wildcard 959 interpretation. 961 4. Usually, a character (determined by the server implementation) is 962 reserved to delimit levels of hierarchy. 964 5. Two characters, "#" and "&", have meanings by convention, and 965 should be avoided except when used in that convention. See 966 Section 5.1.2.1 and Appendix A.1 respectively. 968 5.1.1. Mailbox Hierarchy Naming 970 If it is desired to export hierarchical mailbox names, mailbox names 971 MUST be left-to-right hierarchical using a single character to 972 separate levels of hierarchy. The same hierarchy separator character 973 is used for all levels of hierarchy within a single name. 975 5.1.2. Namespaces 977 Personal Namespace: A namespace that the server considers within the 978 personal scope of the authenticated user on a particular connection. 979 Typically, only the authenticated user has access to mailboxes in 980 their Personal Namespace. It is the part of the namespace that 981 belongs to the user that is allocated for mailboxes. If an INBOX 982 exists for a user, it MUST appear within the user's personal 983 namespace. In the typical case, there SHOULD be only one Personal 984 Namespace per user on a server. 986 Other Users' Namespace: A namespace that consists of mailboxes from 987 the Personal Namespaces of other users. To access mailboxes in the 988 Other Users' Namespace, the currently authenticated user MUST be 989 explicitly granted access rights. For example, it is common for a 990 manager to grant to their secretary access rights to their mailbox. 991 In the typical case, there SHOULD be only one Other Users' Namespace 992 per user on a server. 994 Shared Namespace: A namespace that consists of mailboxes that are 995 intended to be shared amongst users and do not exist within a user's 996 Personal Namespace. 998 The namespaces a server uses MAY differ on a per-user basis. 1000 5.1.2.1. Historic Mailbox Namespace Naming Convention 1002 By convention, the first hierarchical element of any mailbox name 1003 which begins with "#" identifies the "namespace" of the remainder of 1004 the name. This makes it possible to disambiguate between different 1005 types of mailbox stores, each of which have their own namespaces. 1007 For example, implementations which offer access to USENET 1008 newsgroups MAY use the "#news" namespace to partition the USENET 1009 newsgroup namespace from that of other mailboxes. Thus, the 1010 comp.mail.misc newsgroup would have a mailbox name of 1011 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 1012 a different object (e.g., a user's private mailbox). 1014 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 1015 friendly requiring the "#" character to be represented as %23 when 1016 within URLs. As such, server implementors MAY instead consider using 1017 namespace prefixes that do not contain the "#" character. 1019 5.1.2.2. Common namespace models 1021 Previous version of this protocol does not define a default server 1022 namespace. Two common namespace models have evolved: 1024 The "Personal Mailbox" model, in which the default namespace that is 1025 presented consists of only the user's personal mailboxes. To access 1026 shared mailboxes, the user must use an escape mechanism to reach 1027 another namespace. 1029 The "Complete Hierarchy" model, in which the default namespace that 1030 is presented includes the user's personal mailboxes along with any 1031 other mailboxes they have access to. 1033 5.2. Mailbox Size and Message Status Updates 1035 At any time, a server can send data that the client did not request. 1036 Sometimes, such behavior is required by this specification and/or 1037 extensions. For example, agents other than the server MAY add 1038 messages to the mailbox (e.g., new message delivery), change the 1039 flags of the messages in the mailbox (e.g., simultaneous access to 1040 the same mailbox by multiple agents), or even remove messages from 1041 the mailbox. A server MUST send mailbox size updates automatically 1042 if a mailbox size change is observed during the processing of a 1043 command. A server SHOULD send message flag updates automatically, 1044 without requiring the client to request such updates explicitly. 1046 Special rules exist for server notification of a client about the 1047 removal of messages to prevent synchronization errors; see the 1048 description of the EXPUNGE response (Section 7.5.1) for more detail. 1049 In particular, it is NOT permitted to send an EXISTS response that 1050 would reduce the number of messages in the mailbox; only the EXPUNGE 1051 response can do this. 1053 Regardless of what implementation decisions a client makes on 1054 remembering data from the server, a client implementation MUST 1055 remember mailbox size updates. It MUST NOT assume that any command 1056 after the initial mailbox selection will return the size of the 1057 mailbox. 1059 5.3. Response when no Command in Progress 1061 Server implementations are permitted to send an untagged response 1062 (except for EXPUNGE) while there is no command in progress. Server 1063 implementations that send such responses MUST deal with flow control 1064 considerations. Specifically, they MUST either (1) verify that the 1065 size of the data does not exceed the underlying transport's available 1066 window size, or (2) use non-blocking writes. 1068 5.4. Autologout Timer 1070 If a server has an inactivity autologout timer that applies to 1071 sessions after authentication, the duration of that timer MUST be at 1072 least 30 minutes. The receipt of any command from the client during 1073 that interval resets the autologout timer. 1075 Note that this specification doesn't have any restrictions on 1076 autologout timer used before successful client authentication. In 1077 particular, servers are allowed to use shortened pre-authentication 1078 timer to protect themselves from Denial of Service attacks. 1080 5.5. Multiple Commands in Progress (Command Pipelining) 1082 The client MAY send another command without waiting for the 1083 completion result response of a command, subject to ambiguity rules 1084 (see below) and flow control constraints on the underlying data 1085 stream. Similarly, a server MAY begin processing another command 1086 before processing the current command to completion, subject to 1087 ambiguity rules. However, any command continuation request responses 1088 and command continuations MUST be negotiated before any subsequent 1089 command is initiated. 1091 The exception is if an ambiguity would result because of a command 1092 that would affect the results of other commands. If the server 1093 detects a possible ambiguity, it MUST execute commands to completion 1094 in the order given by the client. 1096 The most obvious example of ambiguity is when a command would affect 1097 the results of another command, e.g., a FETCH of a message's flags 1098 and a STORE of that same message's flags. 1100 A non-obvious ambiguity occurs with commands that permit an untagged 1101 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1102 since an untagged EXPUNGE response can invalidate sequence numbers in 1103 a subsequent command. This is not a problem for FETCH, STORE, or 1104 SEARCH commands because servers are prohibited from sending EXPUNGE 1105 responses while any of those commands are in progress. Therefore, if 1106 the client sends any command other than FETCH, STORE, or SEARCH, it 1107 MUST wait for the completion result response before sending a command 1108 with message sequence numbers. 1110 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1111 and UID SEARCH are in progress. If the client sends a UID 1112 command, it MUST wait for a completion result response before 1113 sending a command which uses message sequence numbers (this may 1114 include UID SEARCH). Any message sequence numbers in an argument 1115 to UID SEARCH are associated with messages prior to the effect of 1116 any untagged EXPUNGE returned by the UID SEARCH. 1118 For example, the following non-waiting command sequences are invalid: 1120 FETCH + NOOP + STORE 1122 STORE + COPY + FETCH 1124 COPY + COPY 1126 The following are examples of valid non-waiting command sequences: 1128 FETCH + STORE + SEARCH + NOOP 1130 STORE + COPY + EXPUNGE 1132 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1133 command sequence, depending upon whether or not the second UID 1134 SEARCH contains message sequence numbers. 1136 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1137 dependency between two commands. See Section 6.4.4.2 for more 1138 considerations about pipelining such dependent commands. 1140 6. Client Commands 1142 IMAP4rev2 commands are described in this section. Commands are 1143 organized by the state in which the command is permitted. Commands 1144 which are permitted in multiple states are listed in the minimum 1145 permitted state (for example, commands valid in authenticated and 1146 selected state are listed in the authenticated state commands). 1148 Command arguments, identified by "Arguments:" in the command 1149 descriptions below, are described by function, not by syntax. The 1150 precise syntax of command arguments is described in the Formal Syntax 1151 (Section 9). 1153 Some commands cause specific server responses to be returned; these 1154 are identified by "Responses:" in the command descriptions below. 1155 See the response descriptions in the Responses section (Section 7) 1156 for information on these responses, and the Formal Syntax (Section 9) 1157 for the precise syntax of these responses. It is possible for server 1158 data to be transmitted as a result of any command. Thus, commands 1159 that do not specifically require server data specify "no specific 1160 responses for this command" instead of "none". 1162 The "Result:" in the command description refers to the possible 1163 tagged status responses to a command, and any special interpretation 1164 of these status responses. 1166 The state of a connection is only changed by successful commands 1167 which are documented as changing state. A rejected command (BAD 1168 response) never changes the state of the connection or of the 1169 selected mailbox. A failed command (NO response) generally does not 1170 change the state of the connection or of the selected mailbox; the 1171 exception being the SELECT and EXAMINE commands. 1173 6.1. Client Commands - Any State 1175 The following commands are valid in any state: CAPABILITY, NOOP, and 1176 LOGOUT. 1178 6.1.1. CAPABILITY Command 1180 Arguments: none 1182 Responses: REQUIRED untagged response: CAPABILITY 1184 Result: OK - capability completed 1185 BAD - arguments invalid 1187 The CAPABILITY command requests a listing of capabilities (e.g. 1188 extensions and/or modifications of server behaviour) that the server 1189 supports. The server MUST send a single untagged CAPABILITY response 1190 with "IMAP4rev2" as one of the listed capabilities before the 1191 (tagged) OK response. 1193 A capability name which begins with "AUTH=" indicates that the server 1194 supports that particular authentication mechanism as defined in 1195 [SASL]. All such names are, by definition, part of this 1196 specification. 1198 Other capability names refer to extensions, revisions, or amendments 1199 to this specification. See the documentation of the CAPABILITY 1200 response in Section 7.2.2 for additional information. No 1201 capabilities, beyond the base IMAP4rev2 set defined in this 1202 specification, are enabled without explicit client action to invoke 1203 the capability. 1205 Client and server implementations MUST implement the STARTTLS 1206 Section 6.2.1, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 1207 capabilities. See the Security Considerations (Section 11) for 1208 important information. 1210 Unless specified otherwise, all registered extensions to IMAP4rev1 1211 are also valid extensions to IMAP4rev2. 1213 Example: C: abcd CAPABILITY 1214 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1215 LOGINDISABLED 1216 S: abcd OK CAPABILITY completed 1217 C: efgh STARTTLS 1218 S: efgh OK STARTLS completed 1219 1220 C: ijkl CAPABILITY 1221 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1222 S: ijkl OK CAPABILITY completed 1224 6.1.2. NOOP Command 1226 Arguments: none 1228 Responses: no specific responses for this command (but see below) 1230 Result: OK - noop completed 1231 BAD - command unknown or arguments invalid 1233 The NOOP command always succeeds. It does nothing. 1235 Since any command can return a status update as untagged data, the 1236 NOOP command can be used as a periodic poll for new messages or 1237 message status updates during a period of inactivity (the IDLE 1238 command Section 6.3.13 should be used instead of NOOP if real-time 1239 updates to mailbox state are desirable). The NOOP command can also 1240 be used to reset any inactivity autologout timer on the server. 1242 Example: C: a002 NOOP 1243 S: a002 OK NOOP completed 1244 . . . 1245 C: a047 NOOP 1246 S: * 22 EXPUNGE 1247 S: * 23 EXISTS 1248 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1249 S: a047 OK NOOP completed 1251 6.1.3. LOGOUT Command 1253 Arguments: none 1255 Responses: REQUIRED untagged response: BYE 1257 Result: OK - logout completed 1258 BAD - command unknown or arguments invalid 1260 The LOGOUT command informs the server that the client is done with 1261 the connection. The server MUST send a BYE untagged response before 1262 the (tagged) OK response, and then close the network connection. 1264 Example: C: A023 LOGOUT 1265 S: * BYE IMAP4rev2 Server logging out 1266 S: A023 OK LOGOUT completed 1267 (Server and client then close the connection) 1269 6.2. Client Commands - Not Authenticated State 1271 In the not authenticated state, the AUTHENTICATE or LOGIN command 1272 establishes authentication and enters the authenticated state. The 1273 AUTHENTICATE command provides a general mechanism for a variety of 1274 authentication techniques, privacy protection, and integrity 1275 checking; whereas the LOGIN command uses a traditional user name and 1276 plaintext password pair and has no means of establishing privacy 1277 protection or integrity checking. 1279 The STARTTLS command is an alternative form of establishing session 1280 privacy protection and integrity checking, but does not by itself 1281 establish authentication or enter the authenticated state. 1283 Server implementations MAY allow access to certain mailboxes without 1284 establishing authentication. This can be done by means of the 1285 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1286 convention is a LOGIN command using the userid "anonymous"; in this 1287 case, a password is required although the server may choose to accept 1288 any password. The restrictions placed on anonymous users are 1289 implementation-dependent. 1291 Once authenticated (including as anonymous), it is not possible to 1292 re-enter not authenticated state. 1294 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1295 the following commands are valid in the not authenticated state: 1296 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1297 (Section 11) for important information about these commands. 1299 6.2.1. STARTTLS Command 1301 Arguments: none 1303 Responses: no specific response for this command 1305 Result: OK - starttls completed, begin TLS negotiation 1306 NO - TLS negotiation can't be initiated, due to server 1307 configuration error 1308 BAD - STARTTLS received after a successful TLS 1309 negotiation or arguments invalid 1311 A TLS [TLS-1.3] negotiation begins immediately after the CRLF at the 1312 end of the tagged OK response from the server. Once a client issues 1313 a STARTTLS command, it MUST NOT issue further commands until a server 1314 response is seen and the TLS negotiation is complete. Some past 1315 server implementation incorrectly implemented STARTTLS processing and 1316 are known to contain STARTTLS plaintext command injection 1317 vulnerability [CERT-555316]. In order to avoid this vulnerability, 1318 server implementations MUST do one of the following If any data is 1319 received in the same TCP buffer after the CRLF that starts the 1320 STARTTLS command: 1322 1. Extra data from the TCP buffer is interpreted as beginning of the 1323 TLS handshake. (If the data is in cleartext, this will result in 1324 the TLS handshake failing.) 1326 2. Extra data from the TCP buffer is thrown away. 1328 Note that the first option is friendlier to clients that pipeline 1329 beginning of STARTTLS command with TLS handshake data. 1331 After successful TLS negotiation the server remains in the non- 1332 authenticated state, even if client credentials are supplied during 1333 the TLS negotiation. This does not preclude an authentication 1334 mechanism such as EXTERNAL (defined in [SASL]) from using client 1335 identity determined by the TLS negotiation. 1337 Once TLS has been started, the client MUST discard cached information 1338 about server capabilities and SHOULD re-issue the CAPABILITY command. 1339 This is necessary to protect against man-in- the-middle attacks which 1340 alter the capabilities list prior to STARTTLS. The server MAY 1341 advertise different capabilities, and in particular SHOULD NOT 1342 advertise the STARTTLS capability, after a successful STARTTLS 1343 command. 1345 Example: C: a001 CAPABILITY 1346 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1347 S: a001 OK CAPABILITY completed 1348 C: a002 STARTTLS 1349 S: a002 OK Begin TLS negotiation now 1350 1351 C: a003 CAPABILITY 1352 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1353 S: a003 OK CAPABILITY completed 1354 C: a004 LOGIN joe password 1355 S: a004 OK LOGIN completed 1357 6.2.2. AUTHENTICATE Command 1359 Arguments: SASL authentication mechanism name 1360 OPTIONAL initial response 1362 Responses: continuation data can be requested 1364 Result: OK - authenticate completed, now in authenticated state 1365 NO - authenticate failure: unsupported authentication 1366 mechanism, credentials rejected 1367 BAD - command unknown or arguments invalid, 1368 authentication exchange cancelled 1370 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1371 to the server. If the server supports the requested authentication 1372 mechanism, it performs an authentication protocol exchange to 1373 authenticate and identify the client. It MAY also negotiate an 1374 OPTIONAL security layer for subsequent protocol interactions. If the 1375 requested authentication mechanism is not supported, the server 1376 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1377 response. 1379 The AUTHENTICATE command supports the optional "initial response" 1380 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1381 use it. If a SASL mechanism supports "initial response", but it is 1382 not specified by the client, the server handles this as specified in 1383 Section 3 of [SASL]. 1385 The service name specified by this protocol's profile of [SASL] is 1386 "imap". 1388 The authentication protocol exchange consists of a series of server 1389 challenges and client responses that are specific to the 1390 authentication mechanism. A server challenge consists of a command 1391 continuation request response with the "+" token followed by a BASE64 1392 encoded (see Section 4 of [RFC4648]) string. The client response 1393 consists of a single line consisting of a BASE64 encoded string. If 1394 the client wishes to cancel an authentication exchange, it issues a 1395 line consisting of a single "*". If the server receives such a 1396 response, or if it receives an invalid BASE64 string (e.g. 1397 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1398 reject the AUTHENTICATE command by sending a tagged BAD response. 1400 As with any other client response, this initial response MUST be 1401 encoded as BASE64. It also MUST be transmitted outside of a quoted 1402 string or literal. To send a zero-length initial response, the 1403 client MUST send a single pad character ("="). This indicates that 1404 the response is present, but is a zero-length string. 1406 When decoding the BASE64 data in the initial response, decoding 1407 errors MUST be treated as in any normal SASL client response, i.e. 1408 with a tagged BAD response. In particular, the server should check 1409 for any characters not explicitly allowed by the BASE64 alphabet, as 1410 well as any sequence of BASE64 characters that contains the pad 1411 character ('=') anywhere other than the end of the string (e.g., 1412 "=AAA" and "AAA=BBB" are not allowed). 1414 If the client uses an initial response with a SASL mechanism that 1415 does not support an initial response, the server MUST reject the 1416 command with a tagged BAD response. 1418 If a security layer is negotiated through the [SASL] authentication 1419 exchange, it takes effect immediately following the CRLF that 1420 concludes the authentication exchange for the client, and the CRLF of 1421 the tagged OK response for the server. 1423 While client and server implementations MUST implement the 1424 AUTHENTICATE command itself, it is not required to implement any 1425 authentication mechanisms other than the PLAIN mechanism described in 1426 [PLAIN]. Also, an authentication mechanism is not required to 1427 support any security layers. 1429 Note: a server implementation MUST implement a configuration in 1430 which it does NOT permit any plaintext password mechanisms, unless 1431 either the STARTTLS command has been negotiated or some other 1432 mechanism that protects the session from password snooping has 1433 been provided. Server sites SHOULD NOT use any configuration 1434 which permits a plaintext password mechanism without such a 1435 protection mechanism against password snooping. Client and server 1436 implementations SHOULD implement additional [SASL] mechanisms that 1437 do not use plaintext passwords, such the GSSAPI mechanism 1438 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1439 [SCRAM-SHA-256] mechanisms. 1441 Servers and clients can support multiple authentication mechanisms. 1442 The server SHOULD list its supported authentication mechanisms in the 1443 response to the CAPABILITY command so that the client knows which 1444 authentication mechanisms to use. 1446 A server MAY include a CAPABILITY response code in the tagged OK 1447 response of a successful AUTHENTICATE command in order to send 1448 capabilities automatically. It is unnecessary for a client to send a 1449 separate CAPABILITY command if it recognizes these automatic 1450 capabilities. This should only be done if a security layer was not 1451 negotiated by the AUTHENTICATE command, because the tagged OK 1452 response as part of an AUTHENTICATE command is not protected by 1453 encryption/integrity checking. [SASL] requires the client to re- 1454 issue a CAPABILITY command in this case. The server MAY advertise 1455 different capabilities after a successful AUTHENTICATE command. 1457 If an AUTHENTICATE command fails with a NO response, the client MAY 1458 try another authentication mechanism by issuing another AUTHENTICATE 1459 command. It MAY also attempt to authenticate by using the LOGIN 1460 command (see Section 6.2.3 for more detail). In other words, the 1461 client MAY request authentication types in decreasing order of 1462 preference, with the LOGIN command as a last resort. 1464 The authorization identity passed from the client to the server 1465 during the authentication exchange is interpreted by the server as 1466 the user name whose privileges the client is requesting. 1468 Example: S: * OK IMAP4rev2 Server 1469 C: A001 AUTHENTICATE GSSAPI 1470 S: + 1471 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1472 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1473 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1474 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1475 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1476 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1477 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1478 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1479 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1480 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1481 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1482 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1483 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1484 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1485 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1486 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1487 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1488 C: 1489 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1490 ceP2CWY0SR0fAQAgAAQEBAQ= 1491 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1492 wkhbfa2QteAQAgAG1yYwE= 1493 S: A001 OK GSSAPI authentication successful 1495 Note: The line breaks within server challenges and client responses 1496 are for editorial clarity and are not in real authenticators. 1498 6.2.3. LOGIN Command 1500 Arguments: user name 1501 password 1503 Responses: no specific responses for this command 1505 Result: OK - login completed, now in authenticated state 1506 NO - login failure: user name or password rejected 1507 BAD - command unknown or arguments invalid 1509 The LOGIN command identifies the client to the server and carries the 1510 plaintext password authenticating this user. The LOGIN command 1511 SHOULD NOT be used except as a last resort (after attempting and 1512 failing to authenticate using the AUTHENTICATE command one or more 1513 times), and it is recommended that client implementations have a 1514 means to disable any automatic use of the LOGIN command. 1516 A server MAY include a CAPABILITY response code in the tagged OK 1517 response to a successful LOGIN command in order to send capabilities 1518 automatically. It is unnecessary for a client to send a separate 1519 CAPABILITY command if it recognizes these automatic capabilities. 1521 Example: C: a001 LOGIN SMITH SESAME 1522 S: a001 OK LOGIN completed 1524 Note: Use of the LOGIN command over an insecure network (such as the 1525 Internet) is a security risk, because anyone monitoring network 1526 traffic can obtain plaintext passwords. For that reason clients MUST 1527 NOT use LOGIN on unsecure networks. 1529 Unless either the client is accessing IMAP service on IMAPS port 1530 [RFC8314], the STARTTLS command has been negotiated or some other 1531 mechanism that protects the session from password snooping has been 1532 provided, a server implementation MUST implement a configuration in 1533 which it advertises the LOGINDISABLED capability and does NOT permit 1534 the LOGIN command. Server sites SHOULD NOT use any configuration 1535 which permits the LOGIN command without such a protection mechanism 1536 against password snooping. A client implementation MUST NOT send a 1537 LOGIN command if the LOGINDISABLED capability is advertised. 1539 6.3. Client Commands - Authenticated State 1541 In the authenticated state, commands that manipulate mailboxes as 1542 atomic entities are permitted. Of these commands, the SELECT and 1543 EXAMINE commands will select a mailbox for access and enter the 1544 selected state. 1546 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1547 the following commands are valid in the authenticated state: ENABLE, 1548 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1549 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1551 6.3.1. ENABLE Command 1553 Arguments: capability names 1555 Responses: no specific responses for this command 1557 Result: OK - Relevant capabilities enabled 1558 BAD - No arguments, or syntax error in an argument 1560 Several IMAP extensions allow the server to return unsolicited 1561 responses specific to these extensions in certain circumstances. 1562 However, servers cannot send those unsolicited responses (with the 1563 exception of response codes (see Section 7.1) included in tagged or 1564 untagged OK/NO/BAD responses, which can always be sent) until they 1565 know that the clients support such extensions and thus won't choke on 1566 the extension response data. 1568 The ENABLE command provides an explicit indication from the client 1569 that it supports particular extensions. It is designed such that the 1570 client can send a simple constant string with the extensions it 1571 supports, and the server will enable the shared subset that both 1572 support. 1574 The ENABLE command takes a list of capability names, and requests the 1575 server to enable the named extensions. Once enabled using ENABLE, 1576 each extension remains active until the IMAP connection is closed. 1577 For each argument, the server does the following: 1579 o If the argument is not an extension known to the server, the 1580 server MUST ignore the argument. 1582 o If the argument is an extension known to the server, and it is not 1583 specifically permitted to be enabled using ENABLE, the server MUST 1584 ignore the argument. (Note that knowing about an extension 1585 doesn't necessarily imply supporting that extension.) 1587 o If the argument is an extension that is supported by the server 1588 and that needs to be enabled, the server MUST enable the extension 1589 for the duration of the connection. Note that once an extension 1590 is enabled, there is no way to disable it. 1592 If the ENABLE command is successful, the server MUST send an untagged 1593 ENABLED response Section 7.2.1, which includes all enabled extensions 1594 as specified above. The ENABLED response is sent even if no 1595 extensions were enabled. 1597 Clients SHOULD only include extensions that need to be enabled by the 1598 server. For example, a client can enable IMAP4rev2 specific 1599 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1600 CAPABILITY response. Future RFCs may add to this list. 1602 The ENABLE command is only valid in the authenticated state, before 1603 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1604 SELECT/EXAMINE a mailbox; however, server implementations don't have 1605 to check that no mailbox is selected or was previously selected 1606 during the duration of a connection. 1608 The ENABLE command can be issued multiple times in a session. It is 1609 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1610 single command "ENABLE a b c". When multiple ENABLE commands are 1611 issued, each corresponding ENABLED response SHOULD only contain 1612 extensions enabled by the corresponding ENABLE command, i.e. for the 1613 above example, the ENABLED response to "ENABLE c" should not contain 1614 "a" or "b". 1616 There are no limitations on pipelining ENABLE. For example, it is 1617 possible to send ENABLE and then immediately SELECT, or a LOGIN 1618 immediately followed by ENABLE. 1620 The server MUST NOT change the CAPABILITY list as a result of 1621 executing ENABLE; i.e., a CAPABILITY command issued right after an 1622 ENABLE command MUST list the same capabilities as a CAPABILITY 1623 command issued before the ENABLE command. This is demonstrated in 1624 the following example. Note that below "X-GOOD-IDEA" is a fictitious 1625 extension capability that can be ENABLEd. 1627 C: t1 CAPABILITY 1628 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1629 S: t1 OK foo 1630 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1631 S: * ENABLED X-GOOD-IDEA 1632 S: t2 OK foo 1633 C: t3 CAPABILITY 1634 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1635 S: t3 OK foo again 1637 In the following example, the client enables CONDSTORE: 1639 C: a1 ENABLE CONDSTORE 1640 S: * ENABLED CONDSTORE 1641 S: a1 OK Conditional Store enabled 1643 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1644 Command 1646 Designers of IMAP extensions are discouraged from creating extensions 1647 that require ENABLE unless there is no good alternative design. 1648 Specifically, extensions that cause potentially incompatible behavior 1649 changes to deployed server responses (and thus benefit from ENABLE) 1650 have a higher complexity cost than extensions that do not. 1652 6.3.2. SELECT Command 1654 Arguments: mailbox name 1656 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1657 REQUIRED OK untagged responses: PERMANENTFLAGS, 1658 UIDNEXT, UIDVALIDITY 1659 REQUIRED untagged response: LIST 1661 Result: OK - select completed, now in selected state 1662 NO - select failure, now in authenticated state: no 1663 such mailbox, can't access mailbox 1664 BAD - command unknown or arguments invalid 1666 The SELECT command selects a mailbox so that messages in the mailbox 1667 can be accessed. Before returning an OK to the client, the server 1668 MUST send the following untagged data to the client. (The order of 1669 individual responses is not important.) Note that earlier versions 1670 of this protocol (e.g. IMAP2bis) only required the FLAGS and EXISTS 1671 untagged data; consequently, client implementations SHOULD implement 1672 default behavior for missing data as discussed with the individual 1673 item. 1675 FLAGS Defined flags in the mailbox. See the description of the 1676 FLAGS response in Section 7.3.5 for more detail. 1678 EXISTS The number of messages in the mailbox. See the 1679 description of the EXISTS response in Section 7.4.1 for more 1680 detail. 1682 LIST The server MUST return a LIST response with the mailbox name. 1683 If the server allows de-normalized UTF-8 mailbox names (see 1684 Section 5.1) and the supplied mailbox name differs from the 1685 normalized version, the server MUST return LIST with the OLDNAME 1686 extended data item. See Section 6.3.9.7 for more details. 1688 OK [PERMANENTFLAGS ()] A list of message flags that 1689 the client can change permanently. If this is missing, the client 1690 should assume that all flags can be changed permanently. 1692 OK [UIDNEXT ] The next unique identifier value. Refer to 1693 Section 2.3.1.1 for more information. 1695 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1696 Section 2.3.1.1 for more information. 1698 Only one mailbox can be selected at a time in a connection; 1699 simultaneous access to multiple mailboxes requires multiple 1700 connections. The SELECT command automatically deselects any 1701 currently selected mailbox before attempting the new selection. 1702 Consequently, if a mailbox is selected and a SELECT command that 1703 fails is attempted, no mailbox is selected. When deselecting a 1704 selected mailbox, the server MUST return an untagged OK response with 1705 the "[CLOSED]" response code when the currently selected mailbox is 1706 closed (see Paragraph 10). 1708 If the client is permitted to modify the mailbox, the server SHOULD 1709 prefix the text of the tagged OK response with the "[READ-WRITE]" 1710 response code. 1712 If the client is not permitted to modify the mailbox but is permitted 1713 read access, the mailbox is selected as read-only, and the server 1714 MUST prefix the text of the tagged OK response to SELECT with the 1715 "[READ-ONLY]" response code. Read-only access through SELECT differs 1716 from the EXAMINE command in that certain read-only mailboxes MAY 1717 permit the change of permanent state on a per-user (as opposed to 1718 global) basis. Netnews messages marked in a server-based .newsrc 1719 file are an example of such per-user permanent state that can be 1720 modified with read-only mailboxes. 1722 Example: C: A142 SELECT INBOX 1723 S: * 172 EXISTS 1724 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1725 S: * OK [UIDNEXT 4392] Predicted next UID 1726 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1727 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1728 S: * LIST () "/" INBOX 1729 S: A142 OK [READ-WRITE] SELECT completed 1731 Example: C: A142 SELECT INBOX 1732 S: * 172 EXISTS 1733 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1734 S: * OK [UIDNEXT 4392] Predicted next UID 1735 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1736 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1737 S: A142 OK [READ-WRITE] SELECT completed 1738 [...some time later...] 1739 C: A143 SELECT Drafts 1740 S: * OK [CLOSED] Previous mailbox is now closed 1741 S: * 5 EXISTS 1742 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1743 S: * OK [UIDNEXT 102] Predicted next UID 1744 S: * LIST () "/" Drafts 1745 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1746 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1747 \Flagged \Draft \*)] System flags and keywords allowed 1748 S: A143 OK [READ-WRITE] SELECT completed 1750 Note that IMAP4rev1 compliant servers can also send the untagged 1751 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1752 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1753 RECENT response. 1755 6.3.3. EXAMINE Command 1757 Arguments: mailbox name 1759 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1760 REQUIRED OK untagged responses: PERMANENTFLAGS, 1761 UIDNEXT, UIDVALIDITY 1762 REQUIRED untagged response: LIST 1764 Result: OK - examine completed, now in selected state 1765 NO - examine failure, now in authenticated state: no 1766 such mailbox, can't access mailbox BAD - command unknown 1767 or arguments invalid 1769 The EXAMINE command is identical to SELECT and returns the same 1770 output; however, the selected mailbox is identified as read-only. No 1771 changes to the permanent state of the mailbox, including per-user 1772 state, are permitted. 1774 The text of the tagged OK response to the EXAMINE command MUST begin 1775 with the "[READ-ONLY]" response code. 1777 Example: C: A932 EXAMINE blurdybloop 1778 S: * 17 EXISTS 1779 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1780 S: * OK [UIDNEXT 4392] Predicted next UID 1781 S: * LIST () "/" blurdybloop 1782 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1783 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1784 S: A932 OK [READ-ONLY] EXAMINE completed 1786 6.3.4. CREATE Command 1788 Arguments: mailbox name 1790 Responses: OPTIONAL untagged response: LIST 1792 Result: OK - create completed 1793 NO - create failure: can't create mailbox with that name 1794 BAD - command unknown or arguments invalid 1796 The CREATE command creates a mailbox with the given name. An OK 1797 response is returned only if a new mailbox with that name has been 1798 created. It is an error to attempt to create INBOX or a mailbox with 1799 a name that refers to an extant mailbox. Any error in creation will 1800 return a tagged NO response. If a client attempts to create a UTF-8 1801 mailbox name that is not a valid Net-Unicode name, the server MUST 1802 reject the creation or convert the name to Net-Unicode prior to 1803 creating the mailbox. If the server decides to convert (normalize) 1804 the name, it SHOULD return an untagged LIST with OLDNAME extended 1805 data item, with the OLDNAME value being the supplied mailbox name and 1806 the name parameter being the normalized mailbox name. (See 1807 Section 6.3.9.7 for more details.) 1809 Mailboxes created in one IMAP session MAY be announced to other IMAP 1810 sessions using unsolicited LIST response. If the server 1811 automatically subscribes a mailbox when it is created, then the 1812 unsolicited LIST response for each affected subscribed mailbox name 1813 MUST include the \Subscribed attribute. 1815 If the mailbox name is suffixed with the server's hierarchy separator 1816 character (as returned from the server by a LIST command), this is a 1817 declaration that the client intends to create mailbox names under 1818 this name in the hierarchy. Server implementations that do not 1819 require this declaration MUST ignore the declaration. In any case, 1820 the name created is without the trailing hierarchy delimiter. 1822 If the server's hierarchy separator character appears elsewhere in 1823 the name, the server SHOULD create any superior hierarchical names 1824 that are needed for the CREATE command to be successfully completed. 1826 In other words, an attempt to create "foo/bar/zap" on a server in 1827 which "/" is the hierarchy separator character SHOULD create foo/ and 1828 foo/bar/ if they do not already exist. 1830 If a new mailbox is created with the same name as a mailbox which was 1831 deleted, its unique identifiers MUST be greater than any unique 1832 identifiers used in the previous incarnation of the mailbox unless 1833 the new incarnation has a different unique identifier validity value. 1834 See the description of the UID command in Section 6.4.9 for more 1835 detail. 1837 Example: C: A003 CREATE owatagusiam/ 1838 S: A003 OK CREATE completed 1839 C: A004 CREATE owatagusiam/blurdybloop 1840 S: A004 OK CREATE completed 1841 C: A005 CREATE NonNormalized 1842 S: * LIST () "/" "Normalized" ("OLDNAME" ("NonNormalized")) 1843 S: A005 OK CREATE completed 1845 (in the last example imagine that "NonNormalized" is 1846 a non NFC normalized Unicode mailbox name and that 1847 "Normalized" is its NFC normalized version.) 1849 Note: The interpretation of this example depends on whether "/" 1850 was returned as the hierarchy separator from LIST. If "/" is the 1851 hierarchy separator, a new level of hierarchy named "owatagusiam" 1852 with a member called "blurdybloop" is created. Otherwise, two 1853 mailboxes at the same hierarchy level are created. 1855 6.3.5. DELETE Command 1857 Arguments: mailbox name 1859 Responses: OPTIONAL untagged response: LIST 1861 Result: OK - delete completed 1862 NO - delete failure: can't delete mailbox with that name 1863 BAD - command unknown or arguments invalid 1865 The DELETE command permanently removes the mailbox with the given 1866 name. A tagged OK response is returned only if the mailbox has been 1867 deleted. It is an error to attempt to delete INBOX or a mailbox name 1868 that does not exist. 1870 The DELETE command MUST NOT remove inferior hierarchical names. For 1871 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1872 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1873 "foo.bar". It is an error to attempt to delete a name that has 1874 inferior hierarchical names and also has the \Noselect mailbox name 1875 attribute (see the description of the LIST response (Section 7.3.1) 1876 for more details). 1878 It is permitted to delete a name that has inferior hierarchical names 1879 and does not have the \Noselect mailbox name attribute. If the 1880 server implementation does not permit deleting the name while 1881 inferior hierarchical names exists then it SHOULD disallow the DELETE 1882 command by returning a tagged NO response. The NO response SHOULD 1883 include the HASCHILDREN response code. Alternatively the server MAY 1884 allow the DELETE command, but sets the \Noselect mailbox name 1885 attribute for that name. 1887 If the server returns OK response, all messages in that mailbox are 1888 removed by the DELETE command. 1890 The value of the highest-used unique identifier of the deleted 1891 mailbox MUST be preserved so that a new mailbox created with the same 1892 name will not reuse the identifiers of the former incarnation, unless 1893 the new incarnation has a different unique identifier validity value. 1894 See the description of the UID command in Section 6.4.9 for more 1895 detail. 1897 If the server decides to convert (normalize) the mailbox name, it 1898 SHOULD return an untagged LIST with the "\NonExistent" attribute and 1899 OLDNAME extended data item, with the OLDNAME value being the supplied 1900 mailbox name and the name parameter being the normalized mailbox 1901 name. (See Section 6.3.9.7 for more details.) 1903 Mailboxes deleted in one IMAP session MAY be announced to other IMAP 1904 sessions using unsolicited LIST response, containing the 1905 "\NonExistent" attribute. 1907 Examples: C: A682 LIST "" * 1908 S: * LIST () "/" blurdybloop 1909 S: * LIST (\Noselect) "/" foo 1910 S: * LIST () "/" foo/bar 1911 S: A682 OK LIST completed 1912 C: A683 DELETE blurdybloop 1913 S: A683 OK DELETE completed 1914 C: A684 DELETE foo 1915 S: A684 NO Name "foo" has inferior hierarchical names 1916 C: A685 DELETE foo/bar 1917 S: A685 OK DELETE Completed 1918 C: A686 LIST "" * 1919 S: * LIST (\Noselect) "/" foo 1920 S: A686 OK LIST completed 1921 C: A687 DELETE foo 1922 S: A687 OK DELETE Completed 1923 C: A82 LIST "" * 1924 S: * LIST () "." blurdybloop 1925 S: * LIST () "." foo 1926 S: * LIST () "." foo.bar 1927 S: A82 OK LIST completed 1928 C: A83 DELETE blurdybloop 1929 S: A83 OK DELETE completed 1930 C: A84 DELETE foo 1931 S: A84 OK DELETE Completed 1932 C: A85 LIST "" * 1933 S: * LIST () "." foo.bar 1934 S: A85 OK LIST completed 1935 C: A86 LIST "" % 1936 S: * LIST (\Noselect) "." foo 1937 S: A86 OK LIST completed 1939 6.3.6. RENAME Command 1941 Arguments: existing mailbox name 1942 new mailbox name 1944 Responses: OPTIONAL untagged response: LIST 1946 Result: OK - rename completed 1947 NO - rename failure: can't rename mailbox with that name, 1948 can't rename to mailbox with that name 1949 BAD - command unknown or arguments invalid 1951 The RENAME command changes the name of a mailbox. A tagged OK 1952 response is returned only if the mailbox has been renamed. It is an 1953 error to attempt to rename from a mailbox name that does not exist or 1954 to a mailbox name that already exists. Any error in renaming will 1955 return a tagged NO response. 1957 If the name has inferior hierarchical names, then the inferior 1958 hierarchical names MUST also be renamed. For example, a rename of 1959 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1960 delimiter character) to "zap/bar". 1962 If the server's hierarchy separator character appears in the name, 1963 the server SHOULD create any superior hierarchical names that are 1964 needed for the RENAME command to complete successfully. In other 1965 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1966 server in which "/" is the hierarchy separator character in the 1967 corresponding namespace SHOULD create baz/ and baz/rag/ if they do 1968 not already exist. 1970 The value of the highest-used unique identifier of the old mailbox 1971 name MUST be preserved so that a new mailbox created with the same 1972 name will not reuse the identifiers of the former incarnation, unless 1973 the new incarnation has a different unique identifier validity value. 1974 See the description of the UID command in Section 6.4.9 for more 1975 detail. 1977 Renaming INBOX is permitted (i.e. it doesn't result in a tagged BAD 1978 response), and has special behavior. (Note that some servers 1979 disallow renaming INBOX by returning a tagged NO response, so clients 1980 need to be able to handle such RENAME failing). It moves all 1981 messages in INBOX to a new mailbox with the given name, leaving INBOX 1982 empty. If the server implementation supports inferior hierarchical 1983 names of INBOX, these are unaffected by a rename of INBOX. 1985 If the server allows creation of mailboxes with names that are not 1986 valid Net-Unicode names, the server normalizes both the existing 1987 mailbox name parameter and the new mailbox name parameter. If the 1988 normalized version of any of these 2 parameters differs from the 1989 corresponding supplied version, the server SHOULD return an untagged 1990 LIST response with OLDNAME extended data item, with the OLDNAME value 1991 being the supplied existing mailbox name and the name parameter being 1992 the normalized new mailbox name (see Section 6.3.9.7). This would 1993 allow the client to correlate supplied name with the normalized name. 1995 Mailboxes renamed in one IMAP session MAY be announced to other IMAP 1996 sessions using unsolicited LIST response with OLDNAME extended data 1997 item. 1999 In both of the above cases: if the server automatically subscribes a 2000 mailbox when it is renamed, then the unsolicited LIST response for 2001 each affected subscribed mailbox name MUST include the \Subscribed 2002 attribute. No unsolicited LIST responses need to be sent for 2003 children mailboxes, if any. When INBOX is successfully renamed, a 2004 new INBOX is assumed to be created. No unsolicited LIST responses 2005 need to be sent for INBOX in this case. 2007 Examples: C: A682 LIST "" * 2008 S: * LIST () "/" blurdybloop 2009 S: * LIST (\Noselect) "/" foo 2010 S: * LIST () "/" foo/bar 2011 S: A682 OK LIST completed 2012 C: A683 RENAME blurdybloop sarasoop 2013 S: A683 OK RENAME completed 2014 C: A684 RENAME foo zowie 2015 S: A684 OK RENAME Completed 2016 C: A685 LIST "" * 2017 S: * LIST () "/" sarasoop 2018 S: * LIST (\Noselect) "/" zowie 2019 S: * LIST () "/" zowie/bar 2020 S: A685 OK LIST completed 2022 C: Z432 LIST "" * 2023 S: * LIST () "." INBOX 2024 S: * LIST () "." INBOX.bar 2025 S: Z432 OK LIST completed 2026 C: Z433 RENAME INBOX old-mail 2027 S: Z433 OK RENAME completed 2028 C: Z434 LIST "" * 2029 S: * LIST () "." INBOX 2030 S: * LIST () "." INBOX.bar 2031 S: * LIST () "." old-mail 2032 S: Z434 OK LIST completed 2034 Note that renaming a mailbox doesn't update subscription information 2035 on the original name. To keep subscription information in sync, the 2036 following sequence of commands can be used: 2038 C: 1001 RENAME X Y 2039 C: 1002 SUBSCRIBE Y 2040 C: 1003 UNSUBSCRIBE X 2042 Note that the above sequence of commands doesn't account for updating 2043 subscription for any children mailboxes of mailbox X. 2045 6.3.7. SUBSCRIBE Command 2047 Arguments: mailbox 2049 Responses: no specific responses for this command 2050 Result: OK - subscribe completed 2051 NO - subscribe failure: can't subscribe to that name 2052 BAD - command unknown or arguments invalid 2054 The SUBSCRIBE command adds the specified mailbox name to the server's 2055 set of "active" or "subscribed" mailboxes as returned by the LIST 2056 (SUBSCRIBED) command. This command returns a tagged OK response if 2057 the subscription is successful or if the mailbox is already 2058 subscribed. 2060 A server MAY validate the mailbox argument to SUBSCRIBE to verify 2061 that it exists. However, it SHOULD NOT unilaterally remove an 2062 existing mailbox name from the subscription list even if a mailbox by 2063 that name no longer exists. 2065 Note: This requirement is because a server site can choose to 2066 routinely remove a mailbox with a well-known name (e.g., "system- 2067 alerts") after its contents expire, with the intention of 2068 recreating it when new contents are appropriate. 2070 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 2071 S: A002 OK SUBSCRIBE completed 2073 6.3.8. UNSUBSCRIBE Command 2075 Arguments: mailbox name 2077 Responses: no specific responses for this command 2079 Result: OK - unsubscribe completed 2080 NO - unsubscribe failure: can't unsubscribe that name 2081 BAD - command unknown or arguments invalid 2083 The UNSUBSCRIBE command removes the specified mailbox name from the 2084 server's set of "active" or "subscribed" mailboxes as returned by the 2085 LIST (SUBSCRIBED) command. This command returns a tagged OK response 2086 if the unsubscription is successful or if the mailbox is not 2087 subscribed. 2089 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 2090 S: A002 OK UNSUBSCRIBE completed 2092 6.3.9. LIST Command 2094 Arguments (basic): reference name 2095 mailbox name with possible wildcards 2097 Arguments (extended): selection options (OPTIONAL) 2098 reference name 2099 mailbox patterns 2100 return options (OPTIONAL) 2102 Responses: untagged responses: LIST 2104 Result: OK - list completed 2105 NO - list failure: can't list that reference or mailbox 2106 name 2107 BAD - command unknown or arguments invalid 2109 The LIST command returns a subset of mailbox names from the complete 2110 set of all mailbox names available to the client. Zero or more 2111 untagged LIST responses are returned, containing the name attributes, 2112 hierarchy delimiter, name, and possible extension information; see 2113 the description of the LIST response (Section 7.3.1) for more detail. 2115 The LIST command SHOULD return its data quickly, without undue delay. 2116 For example, it SHOULD NOT go to excess trouble to calculate the 2117 \Marked or \Unmarked status or perform other processing; if each name 2118 requires 1 second of processing, then a list of 1200 names would take 2119 20 minutes! 2121 The extended LIST command, originally introduced in [RFC5258], 2122 provides capabilities beyond that of the original IMAP LIST command. 2123 The extended syntax is being used if one or more of the following 2124 conditions is true: 2126 1. if the first word after the command name begins with a 2127 parenthesis ("LIST selection options"); 2129 2. if the second word after the command name begins with a 2130 parenthesis; 2132 3. if the LIST command has more than 2 parameters ("LIST return 2133 options") 2135 An empty ("" string) reference name argument indicates that the 2136 mailbox name is interpreted as by SELECT. The returned mailbox names 2137 MUST match the supplied mailbox name pattern(s). A non-empty 2138 reference name argument is the name of a mailbox or a level of 2139 mailbox hierarchy, and indicates the context in which the mailbox 2140 name is interpreted. Clients SHOULD use the empty reference 2141 argument. 2143 In the basic syntax only, an empty ("" string) mailbox name argument 2144 is a special request to return the hierarchy delimiter and the root 2145 name of the name given in the reference. The value returned as the 2146 root MAY be the empty string if the reference is non-rooted or is an 2147 empty string. In all cases, a hierarchy delimiter (or NIL if there 2148 is no hierarchy) is returned. This permits a client to get the 2149 hierarchy delimiter (or find out that the mailbox names are flat) 2150 even when no mailboxes by that name currently exist. 2152 In the extended syntax, any mailbox name arguments that are empty 2153 strings are ignored. There is no special meaning for empty mailbox 2154 names when the extended syntax is used. 2156 The reference and mailbox name arguments are interpreted into a 2157 canonical form that represents an unambiguous left-to-right 2158 hierarchy. The returned mailbox names will be in the interpreted 2159 form, that we call "canonical LIST pattern" later in this document. 2160 To define the term "canonical LIST pattern" formally: it refers to 2161 the canonical pattern constructed internally by the server from the 2162 reference and mailbox name arguments. 2164 Note: The interpretation of the reference argument is 2165 implementation-defined. It depends upon whether the server 2166 implementation has a concept of the "current working directory" 2167 and leading "break out characters", which override the current 2168 working directory. 2170 For example, on a server which exports a UNIX or NT filesystem, 2171 the reference argument contains the current working directory, and 2172 the mailbox name argument would contain the name as interpreted in 2173 the current working directory. 2175 If a server implementation has no concept of break out characters, 2176 the canonical form is normally the reference name appended with 2177 the mailbox name. Note that if the server implements the 2178 namespace convention (Section 5.1.2.1), "#" is a break out 2179 character and must be treated as such. 2181 If the reference argument is not a level of mailbox hierarchy 2182 (that is, it is a \NoInferiors name), and/or the reference 2183 argument does not end with the hierarchy delimiter, it is 2184 implementation-dependent how this is interpreted. For example, a 2185 reference of "foo/bar" and mailbox name of "rag/baz" could be 2186 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2187 baz". A client SHOULD NOT use such a reference argument except at 2188 the explicit request of the user. A hierarchical browser MUST NOT 2189 make any assumptions about server interpretation of the reference 2190 unless the reference is a level of mailbox hierarchy AND ends with 2191 the hierarchy delimiter. 2193 Any part of the reference argument that is included in the 2194 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2195 be in the same form as the reference name argument. This rule 2196 permits the client to determine if the returned mailbox name is in 2197 the context of the reference argument, or if something about the 2198 mailbox argument overrode the reference argument. Without this rule, 2199 the client would have to have knowledge of the server's naming 2200 semantics including what characters are "breakouts" that override a 2201 naming context. 2203 Here are some examples of how references 2204 and mailbox names might be interpreted on a UNIX-based 2205 server: 2207 Reference Mailbox Name Interpretation 2208 ------------ ------------ -------------- 2209 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2210 archive/ % archive/% 2211 #news. comp.mail.* #news.comp.mail.* 2212 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2213 archive/ ~fred/Mail/* ~fred/Mail/* 2215 The first three examples demonstrate interpretations in 2216 the context of the reference argument. Note that 2217 "~smith/Mail" SHOULD NOT be transformed into something 2218 like "/u2/users/smith/Mail", or it would be impossible 2219 for the client to determine that the interpretation was 2220 in the context of the reference. 2222 The character "*" is a wildcard, and matches zero or more characters 2223 at this position. The character "%" is similar to "*", but it does 2224 not match a hierarchy delimiter. If the "%" wildcard is the last 2225 character of a mailbox name argument, matching levels of hierarchy 2226 are also returned. If these levels of hierarchy are not also 2227 selectable mailboxes, they are returned with the \Noselect mailbox 2228 name attribute (see the description of the LIST response 2229 (Section 7.3.1) for more details). 2231 Any syntactically valid pattern that is not accepted by a server for 2232 any reason MUST be silently ignored. I.e. it results in no LIST 2233 responses and the LIST command still returns tagged OK response. 2235 Selection options tell the server to limit the mailbox names that are 2236 selected by the LIST operation. If selection options are used, the 2237 mailboxes returned are those that match both the list of canonical 2238 LIST patterns and the selection options. Unless a particular 2239 selection option provides special rules, the selection options are 2240 cumulative: a mailbox that matches the mailbox patterns is selected 2241 only if it also matches all of the selection options. (An example of 2242 a selection option with special rules is the RECURSIVEMATCH option.) 2244 Return options control what information is returned for each matched 2245 mailbox. Return options MUST NOT cause the server to report 2246 information about additional mailbox names other than those that 2247 match the canonical LIST patterns and selection options. If no 2248 return options are specified, the client is only expecting 2249 information about mailbox attributes. The server MAY return other 2250 information about the matched mailboxes, and clients MUST be able to 2251 handle that situation. 2253 Initial selection options and return options are defined in the 2254 following subsections, and new ones will also be defined in 2255 extensions. Initial options defined in this document MUST be 2256 supported. Each non-initial option will be enabled by a capability 2257 string (one capability may enable multiple options), and a client 2258 MUST NOT send an option for which the server has not advertised 2259 support. A server MUST respond to options it does not recognize with 2260 a BAD response. The client SHOULD NOT specify any option more than 2261 once; however, if the client does this, the server MUST act as if it 2262 received the option only once. The order in which options are 2263 specified by the client is not significant. 2265 In general, each selection option except RECURSIVEMATCH will have a 2266 corresponding return option with the same name. The REMOTE selection 2267 option is an anomaly in this regard, and does not have a 2268 corresponding return option. That is because it expands, rather than 2269 restricts, the set of mailboxes that are returned. Future extensions 2270 to this specification should keep this parallelism in mind and define 2271 a pair of corresponding selection and return options. 2273 Server implementations are permitted to "hide" otherwise accessible 2274 mailboxes from the wildcard characters, by preventing certain 2275 characters or names from matching a wildcard in certain situations. 2276 For example, a UNIX-based server might restrict the interpretation of 2277 "*" so that an initial "/" character does not match. 2279 The special name INBOX is included in the output from LIST, if INBOX 2280 is supported by this server for this user and if the uppercase string 2281 "INBOX" matches the interpreted reference and mailbox name arguments 2282 with wildcards as described above. The criteria for omitting INBOX 2283 is whether SELECT INBOX will return failure; it is not relevant 2284 whether the user's real INBOX resides on this or some other server. 2286 6.3.9.1. LIST Selection Options 2288 The selection options defined in this specification are as follows: 2290 SUBSCRIBED - causes the LIST command to list subscribed names, 2291 rather than the existing mailboxes. This will often be a subset 2292 of the actual mailboxes. It's also possible for this list to 2293 contain the names of mailboxes that don't exist. In any case, the 2294 list MUST include exactly those mailbox names that match the 2295 canonical list pattern and are subscribed to. 2297 This option defines a mailbox attribute, "\Subscribed", that 2298 indicates that a mailbox name is subscribed to. The "\Subscribed" 2299 attribute MUST be supported and MUST be accurately computed when 2300 the SUBSCRIBED selection option is specified. 2302 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2303 return option (see below). 2305 REMOTE - causes the LIST command to show remote mailboxes as well as 2306 local ones, as described in [RFC2193]. This option is intended to 2307 replace the RLIST command and, in conjunction with the SUBSCRIBED 2308 selection option, the RLSUB command. Servers that don't support 2309 remote mailboxes just ignore this option. 2311 This option defines a mailbox attribute, "\Remote", that indicates 2312 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2313 be accurately computed when the REMOTE option is specified. 2315 The REMOTE selection option has no interaction with other options. 2316 Its effect is to tell the server to apply the other options, if 2317 any, to remote mailboxes, in addition to local ones. In 2318 particular, it has no interaction with RECURSIVEMATCH (see below). 2319 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2320 request for (RECURSIVEMATCH) is also invalid. A request for 2321 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2322 mailboxes, both local and remote. 2324 RECURSIVEMATCH - this option forces the server to return information 2325 about parent mailboxes that don't match other selection options, 2326 but have some submailboxes that do. Information about children is 2327 returned in the CHILDINFO extended data item, as described in 2328 Section 6.3.9.6. 2330 Note 1: In order for a parent mailbox to be returned, it still has 2331 to match the canonical LIST pattern. 2333 Note 2: When returning the CHILDINFO extended data item, it 2334 doesn't matter whether or not the submailbox matches the canonical 2335 LIST pattern. See also example 9 in Section 6.3.9.8. 2337 The RECURSIVEMATCH option MUST NOT occur as the only selection 2338 option (or only with REMOTE), as it only makes sense when other 2339 selection options are also used. The server MUST return BAD 2340 tagged response in such case. 2342 Note that even if the RECURSIVEMATCH option is specified, the 2343 client MUST still be able to handle a case when a CHILDINFO 2344 extended data item is returned and there are no submailboxes that 2345 meet the selection criteria of the subsequent LIST command, as 2346 they can be deleted/renamed after the LIST response was sent, but 2347 before the client had a chance to access them. 2349 6.3.9.2. LIST Return Options 2351 The return options defined in this specification are as follows: 2353 SUBSCRIBED - causes the LIST command to return subscription state 2354 for all matching mailbox names. The "\Subscribed" attribute MUST 2355 be supported and MUST be accurately computed when the SUBSCRIBED 2356 return option is specified. Further, all mailbox flags MUST be 2357 accurately computed (this differs from the behavior of the 2358 obsolete LSUB command from IMAP4rev1). 2360 CHILDREN - requests mailbox child information as originally proposed 2361 in [RFC3348]. See Section 6.3.9.5, below, for details. 2363 STATUS - requests STATUS response for each matching mailbox. 2365 This option takes STATUS data items as parameters. For each 2366 selectable mailbox matching the list pattern and selection 2367 options, the server MUST return an untagged LIST response 2368 followed by an untagged STATUS response containing the 2369 information requested in the STATUS return option, except for 2370 some cases described below. 2372 If an attempted STATUS for a listed mailbox fails because the 2373 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2374 is granted to the mailbox and the "r" right is not granted, or 2375 due to a race condition between LIST and STATUS changing the 2376 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2377 and the LIST response MUST include the \NoSelect attribute. 2378 This means the server may have to buffer the LIST reply until 2379 it has successfully looked up the necessary STATUS information. 2381 If the server runs into unexpected problems while trying to 2382 look up the STATUS information, it MAY drop the corresponding 2383 STATUS reply. In such a situation, the LIST command would 2384 still return a tagged OK reply. 2386 6.3.9.3. General Principles for Returning LIST Responses 2388 This section outlines several principles that can be used by server 2389 implementations of this document to decide whether a LIST response 2390 should be returned, as well as how many responses and what kind of 2391 information they may contain. 2393 1. At most one LIST response should be returned for each mailbox 2394 name that matches the canonical LIST pattern. Server 2395 implementors must not assume that clients will be able to 2396 assemble mailbox attributes and other information returned in 2397 multiple LIST responses. 2399 2. There are only two reasons for including a matching mailbox name 2400 in the responses to the LIST command (note that the server is 2401 allowed to return unsolicited responses at any time, and such 2402 responses are not governed by this rule): 2404 A. The mailbox name also satisfies the selection criteria. 2406 B. The mailbox name doesn't satisfy the selection criteria, but 2407 it has at least one descendant mailbox name that satisfies 2408 the selection criteria and that doesn't match the canonical 2409 LIST pattern. 2411 For more information on this case, see the CHILDINFO extended 2412 data item described in Section 6.3.9.6. Note that the 2413 CHILDINFO extended data item can only be returned when the 2414 RECURSIVEMATCH selection option is specified. 2416 3. Attributes returned in the same LIST response must be treated 2417 additively. For example, the following response 2419 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2421 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2422 subscribed. 2424 6.3.9.4. Additional LIST-related Requirements on Clients 2426 All clients MUST treat a LIST attribute with a stronger meaning as 2427 implying any attribute that can be inferred from it. (See 2428 Section 7.3.1 for the list of currently defined attributes). For 2429 example, the client must treat the presence of the \NoInferiors 2430 attribute as if the \HasNoChildren attribute was also sent by the 2431 server. 2433 The following table summarizes inference rules. 2435 +--------------------+-------------------+ 2436 | returned attribute | implied attribute | 2437 +--------------------+-------------------+ 2438 | \NoInferiors | \HasNoChildren | 2439 | \NonExistent | \NoSelect | 2440 +--------------------+-------------------+ 2442 6.3.9.5. The CHILDREN Return Option 2444 The CHILDREN return option is simply an indication that the client 2445 wants information about whether or not mailboxes contain children 2446 mailboxes; a server MAY provide it even if the option is not 2447 specified. 2449 Many IMAP4 clients present to the user a hierarchical view of the 2450 mailboxes that a user has access to. Rather than initially 2451 presenting to the user the entire mailbox hierarchy, it is often 2452 preferable to show to the user a collapsed outline list of the 2453 mailbox hierarchy (particularly if there is a large number of 2454 mailboxes). The user can then expand the collapsed outline hierarchy 2455 as needed. It is common to include within the collapsed hierarchy a 2456 visual clue (such as a ''+'') to indicate that there are child 2457 mailboxes under a particular mailbox. When the visual clue is 2458 clicked, the hierarchy list is expanded to show the child mailboxes. 2459 The CHILDREN return option provides a mechanism for a client to 2460 efficiently determine whether a particular mailbox has children, 2461 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2462 The CHILDREN return option defines two new attributes that MUST be 2463 returned within a LIST response: \HasChildren and \HasNoChildren. 2464 Although these attributes MAY be returned in response to any LIST 2465 command, the CHILDREN return option is provided to indicate that the 2466 client particularly wants this information. If the CHILDREN return 2467 option is present, the server MUST return these attributes even if 2468 their computation is expensive. 2470 \HasChildren 2472 The presence of this attribute indicates that the mailbox has 2473 child mailboxes. A server SHOULD NOT set this attribute if 2474 there are child mailboxes and the user does not have permission 2475 to access any of them. In this case, \HasNoChildren SHOULD be 2476 used. In many cases, however, a server may not be able to 2477 efficiently compute whether a user has access to any child 2478 mailbox. Note that even though the \HasChildren attribute for a 2479 mailbox must be correct at the time of processing of the 2480 mailbox, a client must be prepared to deal with a situation when 2481 a mailbox is marked with the \HasChildren attribute, but no 2482 child mailbox appears in the response to the LIST command. This 2483 might happen, for example, due to children mailboxes being 2484 deleted or made inaccessible to the user (using access control) 2485 by another client before the server is able to list them. 2487 \HasNoChildren 2489 The presence of this attribute indicates that the mailbox has NO 2490 child mailboxes that are accessible to the currently 2491 authenticated user. 2493 It is an error for the server to return both a \HasChildren and a 2494 \HasNoChildren attribute in the same LIST response. 2496 Note: the \HasNoChildren attribute should not be confused with the 2497 the \NoInferiors attribute, which indicates that no child mailboxes 2498 exist now and none can be created in the future. 2500 6.3.9.6. CHILDINFO Extended Data Item 2502 The CHILDINFO extended data item MUST NOT be returned unless the 2503 client has specified the RECURSIVEMATCH selection option. 2505 The CHILDINFO extended data item in a LIST response describes the 2506 selection criteria that has caused it to be returned and indicates 2507 that the mailbox has at least one descendant mailbox that matches the 2508 selection criteria. 2510 Note: Some servers allow for mailboxes to exist without requiring 2511 their parent to exist. For example, a mailbox "Customers/ABC" can 2512 exist while the mailbox "Customers" does not. As CHILDINFO extended 2513 data item is not allowed if the RECURSIVEMATCH selection option is 2514 not specified, such servers SHOULD use the "\NonExistent 2515 \HasChildren" attribute pair to signal to the client that there is a 2516 descendant mailbox that matches the selection criteria. See example 2517 11 in Section 6.3.9.8. 2519 The returned selection criteria allow the client to distinguish a 2520 solicited response from an unsolicited one, as well as to distinguish 2521 among solicited responses caused by multiple pipelined LIST commands 2522 that specify different criteria. 2524 Servers SHOULD only return a non-matching mailbox name along with 2525 CHILDINFO if at least one matching child is not also being returned. 2526 That is, servers SHOULD suppress redundant CHILDINFO responses. 2528 Examples 8 and 10 in Section 6.3.9.8 demonstrate the difference 2529 between present CHILDINFO extended data item and the "\HasChildren" 2530 attribute. 2532 The following table summarizes interaction between the "\NonExistent" 2533 attribute and CHILDINFO (the first column indicates whether the 2534 parent mailbox exists): 2536 +--------+-------------+------------------+-------------------------+ 2537 | exists | meets the | has a child that | returned | 2538 | | selection | meets the | IMAP4rev2/LIST-EXTENDED | 2539 | | criteria | selection | attributes and | 2540 | | | criteria | CHILDINFO | 2541 +--------+-------------+------------------+-------------------------+ 2542 | no | no | no | no LIST response | 2543 | | | | returned | 2544 | yes | no | no | no LIST response | 2545 | | | | returned | 2546 | no | yes | no | (\NonExistent ) | 2547 | yes | yes | no | () | 2548 | no | no | yes | (\NonExistent) + | 2549 | | | | CHILDINFO | 2550 | yes | no | yes | () + CHILDINFO | 2551 | no | yes | yes | (\NonExistent ) + | 2552 | | | | CHILDINFO | 2553 | yes | yes | yes | () + CHILDINFO | 2554 +--------+-------------+------------------+-------------------------+ 2556 where is one or more attributes that correspond to the 2557 selection criteria; for example, for the SUBSCRIBED option the 2558 is \Subscribed. 2560 6.3.9.7. OLDNAME Extended Data Item 2562 The OLDNAME extended data item is included when a mailbox name is 2563 created (with CREATE command), renamed (with RENAME command) or 2564 deleted (with DELETE command). (When a mailbox is deleted the 2565 "\NonExistent" attribute is also included.) IMAP extensions can 2566 specify other conditions when OLDNAME extended data item should be 2567 included. 2569 If the server allows de-normalized mailbox names (see Section 5.1) in 2570 SELECT/EXAMINE, CREATE, RENAME or DELETE, it SHOULD return an 2571 unsolicited LIST response that includes OLDNAME extended data item, 2572 whenever the supplied mailbox name differs from the resulting 2573 normalized mailbox name. From the client point of view this is 2574 indistinguishable from another user renaming or deleting the mailbox, 2575 as specified in the previous paragraph. 2577 A deleted mailbox can be announced like this: 2579 S: * LIST (\NonExistent) "." "INBOX.DeletedMailbox" 2581 Example of a renamed mailbox: 2583 S: * LIST () "/" "NewMailbox" ("OLDNAME" ("OldMailbox")) 2585 6.3.9.8. LIST Command Examples 2587 This example shows some uses of the basic LIST command: 2589 Example: C: A101 LIST "" "" 2590 S: * LIST (\Noselect) "/" "" 2591 S: A101 OK LIST Completed 2592 C: A102 LIST #news.comp.mail.misc "" 2593 S: * LIST (\Noselect) "." #news. 2594 S: A102 OK LIST Completed 2595 C: A103 LIST /usr/staff/jones "" 2596 S: * LIST (\Noselect) "/" / 2597 S: A103 OK LIST Completed 2598 C: A202 LIST ~/Mail/ % 2599 S: * LIST (\Noselect) "/" ~/Mail/foo 2600 S: * LIST () "/" ~/Mail/meetings 2601 S: A202 OK LIST completed 2603 Extended examples: 2605 1: The first example shows the complete local hierarchy that will 2606 be used for the other examples. 2608 C: A01 LIST "" "*" 2609 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2610 S: * LIST () "/" "Fruit" 2611 S: * LIST () "/" "Fruit/Apple" 2612 S: * LIST () "/" "Fruit/Banana" 2613 S: * LIST () "/" "Tofu" 2614 S: * LIST () "/" "Vegetable" 2615 S: * LIST () "/" "Vegetable/Broccoli" 2616 S: * LIST () "/" "Vegetable/Corn" 2617 S: A01 OK done 2619 2: In the next example, we will see the subscribed mailboxes. This 2620 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2622 that the mailbox called "Fruit/Peach" is subscribed to, but does 2623 not actually exist (perhaps it was deleted while still 2624 subscribed). The "Fruit" mailbox is not subscribed to, but it 2625 has two subscribed children. The "Vegetable" mailbox is 2626 subscribed and has two children; one of them is subscribed as 2627 well. 2629 C: A02 LIST (SUBSCRIBED) "" "*" 2630 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2631 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2632 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2633 S: * LIST (\Subscribed) "/" "Vegetable" 2634 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2635 S: A02 OK done 2637 3: The next example shows the use of the CHILDREN option. The 2638 client, without having to list the second level of hierarchy, 2639 now knows which of the top-level mailboxes have submailboxes 2640 (children) and which do not. Note that it's not necessary for 2641 the server to return the \HasNoChildren attribute for the inbox, 2642 because the \NoInferiors attribute already implies that, and has 2643 a stronger meaning. 2645 C: A03 LIST () "" "%" RETURN (CHILDREN) 2646 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2647 S: * LIST (\HasChildren) "/" "Fruit" 2648 S: * LIST (\HasNoChildren) "/" "Tofu" 2649 S: * LIST (\HasChildren) "/" "Vegetable" 2650 S: A03 OK done 2652 4: In this example, we see more mailboxes that reside on another 2653 server. This is similar to the command . 2655 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2656 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2657 S: * LIST (\HasChildren) "/" "Fruit" 2658 S: * LIST (\HasNoChildren) "/" "Tofu" 2659 S: * LIST (\HasChildren) "/" "Vegetable" 2660 S: * LIST (\Remote) "/" "Bread" 2661 S: * LIST (\HasChildren \Remote) "/" "Meat" 2662 S: A04 OK done 2664 5: The following example also requests the server to include 2665 mailboxes that reside on another server. The server returns 2666 information about all mailboxes that are subscribed. This is 2667 similar to the command (see [RFC2193] for more 2668 details on RLSUB). We also see the use of two selection 2669 options. 2671 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2672 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2673 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2674 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2675 S: * LIST (\Subscribed) "/" "Vegetable" 2676 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2677 S: * LIST (\Remote \Subscribed) "/" "Bread" 2678 S: A05 OK done 2680 6: The following example requests the server to include mailboxes 2681 that reside on another server. The server is asked to return 2682 subscription information for all returned mailboxes. This is 2683 different from the example above. 2685 Note that the output of this command is not a superset of the 2686 output in the previous example, as it doesn't include LIST 2687 response for the non-existent "Fruit/Peach". 2689 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2690 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2691 S: * LIST () "/" "Fruit" 2692 S: * LIST () "/" "Fruit/Apple" 2693 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2694 S: * LIST () "/" "Tofu" 2695 S: * LIST (\Subscribed) "/" "Vegetable" 2696 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2697 S: * LIST () "/" "Vegetable/Corn" 2698 S: * LIST (\Remote \Subscribed) "/" "Bread" 2699 S: * LIST (\Remote) "/" "Meat" 2700 S: A06 OK done 2702 7: The following example demonstrates the difference between the 2703 \HasChildren attribute and the CHILDINFO extended data item. 2705 Let's assume there is the following hierarchy: 2707 C: C01 LIST "" "*" 2708 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2709 S: * LIST () "/" "Foo" 2710 S: * LIST () "/" "Foo/Bar" 2711 S: * LIST () "/" "Foo/Baz" 2712 S: * LIST () "/" "Moo" 2713 S: C01 OK done 2714 If the client asks RETURN (CHILDREN), it will get this: 2716 C: CA3 LIST "" "%" RETURN (CHILDREN) 2717 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2718 S: * LIST (\HasChildren) "/" "Foo" 2719 S: * LIST (\HasNoChildren) "/" "Moo" 2720 S: CA3 OK done 2722 A) Let's also assume that the mailbox "Foo/Baz" is the only 2723 subscribed mailbox. Then we get this result: 2725 C: C02 LIST (SUBSCRIBED) "" "*" 2726 S: * LIST (\Subscribed) "/" "Foo/Baz" 2727 S: C02 OK done 2729 Now, if the client issues , the server 2730 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2731 "Inbox" are NOT subscribed). However, if the client issues 2732 this: 2734 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2735 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2736 S: C04 OK done 2738 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2739 that is.) 2741 A1) If the mailbox "Foo" had also been subscribed, the last 2742 command would return this: 2744 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2745 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2746 S: C04 OK done 2748 or even this: 2750 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2751 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2752 ("SUBSCRIBED")) 2753 S: C04 OK done 2755 A2) If we assume instead that the mailbox "Foo" is not part of 2756 the original hierarchy and is not subscribed, the last command 2757 will give this result: 2759 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2760 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2761 S: C04 OK done 2762 B) Now, let's assume that no mailbox is subscribed. In this 2763 case, the command will 2764 return no responses, as there are no subscribed children (even 2765 though "Foo" has children). 2767 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2768 are subscribed. In that case, we see this result: 2770 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2771 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2772 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2773 S: C04 OK done 2775 (which means that the mailbox "Foo" has children, but none of 2776 them is subscribed). 2778 8: The following example demonstrates that the CHILDINFO extended 2779 data item is returned whether or not children mailboxes match 2780 the canonical LIST pattern. 2782 Let's assume there is the following hierarchy: 2784 C: D01 LIST "" "*" 2785 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2786 S: * LIST () "/" "foo2" 2787 S: * LIST () "/" "foo2/bar1" 2788 S: * LIST () "/" "foo2/bar2" 2789 S: * LIST () "/" "baz2" 2790 S: * LIST () "/" "baz2/bar2" 2791 S: * LIST () "/" "baz2/bar22" 2792 S: * LIST () "/" "baz2/bar222" 2793 S: * LIST () "/" "eps2" 2794 S: * LIST () "/" "eps2/mamba" 2795 S: * LIST () "/" "qux2/bar2" 2796 S: D01 OK done 2798 And that the following mailboxes are subscribed: 2800 C: D02 LIST (SUBSCRIBED) "" "*" 2801 S: * LIST (\Subscribed) "/" "foo2/bar1" 2802 S: * LIST (\Subscribed) "/" "foo2/bar2" 2803 S: * LIST (\Subscribed) "/" "baz2/bar2" 2804 S: * LIST (\Subscribed) "/" "baz2/bar22" 2805 S: * LIST (\Subscribed) "/" "baz2/bar222" 2806 S: * LIST (\Subscribed) "/" "eps2" 2807 S: * LIST (\Subscribed) "/" "eps2/mamba" 2808 S: * LIST (\Subscribed) "/" "qux2/bar2" 2809 S: D02 OK done 2810 The client issues the following command first: 2812 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2813 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2814 S: * LIST (\Subscribed) "/" "foo2/bar2" 2815 S: * LIST (\Subscribed) "/" "baz2/bar2" 2816 S: * LIST (\Subscribed) "/" "baz2/bar22" 2817 S: * LIST (\Subscribed) "/" "baz2/bar222" 2818 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2819 S: * LIST (\Subscribed) "/" "qux2/bar2" 2820 S: D03 OK done 2822 and the server may also include (but this would violate a SHOULD 2823 NOT in Section 3.5, because CHILDINFO is redundant) 2825 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2826 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2828 The CHILDINFO extended data item is returned for mailboxes 2829 "foo2", "baz2", and "eps2", because all of them have subscribed 2830 children, even though for the mailbox "foo2" only one of the two 2831 subscribed children matches the pattern, for the mailbox "baz2" 2832 all the subscribed children match the pattern, and for the 2833 mailbox "eps2" none of the subscribed children matches the 2834 pattern. 2836 Note that if the client issues 2838 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2839 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2840 S: * LIST (\Subscribed) "/" "foo2/bar1" 2841 S: * LIST (\Subscribed) "/" "foo2/bar2" 2842 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2843 S: * LIST (\Subscribed) "/" "baz2/bar2" 2844 S: * LIST (\Subscribed) "/" "baz2/bar22" 2845 S: * LIST (\Subscribed) "/" "baz2/bar222" 2846 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2847 S: * LIST (\Subscribed) "/" "eps2/mamba" 2848 S: * LIST (\Subscribed) "/" "qux2/bar2" 2849 S: D03 OK done 2851 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2852 still have the CHILDINFO extended data item, even though this 2853 information is redundant and the client can determine it by 2854 itself. 2856 9: The following example shows usage of extended syntax for mailbox 2857 pattern. It also demonstrates that the presence of the 2858 CHILDINFO extended data item doesn't necessarily imply 2859 \HasChildren. 2861 C: a1 LIST "" ("foo") 2862 S: * LIST () "/" foo 2863 S: a1 OK done 2865 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2866 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2867 S: a2 OK done 2869 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2870 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2871 S: a3 OK done 2873 10: The following example shows how a server that supports missing 2874 mailbox hierarchy elements can signal to a client that didn't 2875 specify the RECURSIVEMATCH selection option that there is a 2876 child mailbox that matches the selection criteria. 2878 C: a1 LIST (REMOTE) "" * 2879 S: * LIST () "/" music/rock 2880 S: * LIST (\Remote) "/" also/jazz 2881 S: a1 OK done 2883 C: a2 LIST () "" % 2884 S: * LIST (\NonExistent \HasChildren) "/" music 2885 S: a2 OK done 2887 C: a3 LIST (REMOTE) "" % 2888 S: * LIST (\NonExistent \HasChildren) "/" music 2889 S: * LIST (\NonExistent \HasChildren) "/" also 2890 S: a3 OK done 2892 C: a3.1 LIST "" (% music/rock) 2893 S: * LIST () "/" music/rock 2894 S: a3.1 OK done 2896 Because "music/rock" is the only mailbox under "music", there's 2897 no need for the server to also return "music". However clients 2898 must handle both cases. 2900 11: The following examples show use of STATUS return option. 2902 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2903 S: * LIST () "." "INBOX" 2904 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2905 S: * LIST () "." "foo" 2906 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2907 S: * LIST (\NoSelect) "." "bar" 2908 S: A01 OK List completed. 2910 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2912 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2913 (MESSAGES)) 2914 S: * LIST (\Subscribed) "." "INBOX" 2915 S: * STATUS "INBOX" (MESSAGES 17) 2916 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2917 S: A02 OK List completed. 2919 The LIST reply for "foo" is returned because it has matching 2920 children, but no STATUS reply is returned because "foo" itself 2921 doesn't match the selection criteria. 2923 6.3.10. NAMESPACE Command 2925 Arguments: none 2927 Responses: REQUIRED untagged responses: NAMESPACE 2929 Result: OK - command completed 2930 NO - Can't complete the command 2931 BAD - arguments invalid 2933 The NAMESPACE command causes a single untagged NAMESPACE response to 2934 be returned. The untagged NAMESPACE response contains the prefix and 2935 hierarchy delimiter to the server's Personal Namespace(s), Other 2936 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2937 to expose. The response will contain a NIL for any namespace class 2938 that is not available. The namespace-response-extensions ABNF non 2939 terminal is defined for extensibility and MAY be included in the 2940 NAMESPACE response. 2942 Example 1: 2944 In this example a server supports a single personal namespace. No 2945 leading prefix is used on personal mailboxes and "/" is the hierarchy 2946 delimiter. 2948 C: A001 NAMESPACE 2949 S: * NAMESPACE (("" "/")) NIL NIL 2950 S: A001 OK NAMESPACE command completed 2952 Example 2: 2954 A user logged on anonymously to a server. No personal mailboxes are 2955 associated with the anonymous user and the user does not have access 2956 to the Other Users' Namespace. No prefix is required to access 2957 shared mailboxes and the hierarchy delimiter is "." 2959 C: A001 NAMESPACE 2960 S: * NAMESPACE NIL NIL (("" ".")) 2961 S: A001 OK NAMESPACE command completed 2963 Example 3: 2965 A server that contains a Personal Namespace and a single Shared 2966 Namespace. 2968 C: A001 NAMESPACE 2969 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2970 S: A001 OK NAMESPACE command completed 2972 Example 4: 2974 A server that contains a Personal Namespace, Other Users' Namespace 2975 and multiple Shared Namespaces. Note that the hierarchy delimiter 2976 used within each namespace can be different. 2978 C: A001 NAMESPACE 2979 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2980 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2981 S: A001 OK NAMESPACE command completed 2983 The prefix string allows a client to do things such as automatically 2984 creating personal mailboxes or LISTing all available mailboxes within 2985 a namespace. 2987 Example 5: 2989 A server that supports only the Personal Namespace, with a leading 2990 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2991 "." 2992 C: A001 NAMESPACE 2993 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2994 S: A001 OK NAMESPACE command completed 2996 < Automatically create a mailbox to store sent items.> 2998 C: A002 CREATE "INBOX.Sent Mail" 2999 S: A002 OK CREATE command completed 3001 Although typically a server will support only a single Personal 3002 Namespace, and a single Other User's Namespace, circumstances exist 3003 where there MAY be multiples of these, and a client MUST be prepared 3004 for them. If a client is configured such that it is required to 3005 create a certain mailbox, there can be circumstances where it is 3006 unclear which Personal Namespaces it should create the mailbox in. 3007 In these situations a client SHOULD let the user select which 3008 namespaces to create the mailbox in or just use the first personal 3009 namespace. 3011 Example 6: 3013 In this example, a server supports two Personal Namespaces. In 3014 addition to the regular Personal Namespace, the user has an 3015 additional personal namespace to allow access to mailboxes in an MH 3016 format mailstore. 3018 The client is configured to save a copy of all mail sent by the user 3019 into a mailbox called 'Sent Mail'. Furthermore, after a message is 3020 deleted from a mailbox, the client is configured to move that message 3021 to a mailbox called 'Deleted Items'. 3023 Note that this example demonstrates how some extension parameters can 3024 be passed to further describe the #mh namespace. See the fictitious 3025 "X-PARAM" extension parameter. 3027 C: A001 NAMESPACE 3028 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 3029 ("FLAG1" "FLAG2"))) NIL NIL 3030 S: A001 OK NAMESPACE command completed 3032 < It is desired to keep only one copy of sent mail. 3033 It is unclear which Personal Namespace the client 3034 should use to create the 'Sent Mail' mailbox. 3035 The user is prompted to select a namespace and only 3036 one 'Sent Mail' mailbox is created. > 3038 C: A002 CREATE "Sent Mail" 3039 S: A002 OK CREATE command completed 3041 < The client is designed so that it keeps two 3042 'Deleted Items' mailboxes, one for each namespace. > 3044 C: A003 CREATE "Delete Items" 3045 S: A003 OK CREATE command completed 3047 C: A004 CREATE "#mh/Deleted Items" 3048 S: A004 OK CREATE command completed 3050 The next level of hierarchy following the Other Users' Namespace 3051 prefix SHOULD consist of , where is a user name 3052 as per the LOGIN or AUTHENTICATE command. 3054 A client can construct a LIST command by appending a "%" to the Other 3055 Users' Namespace prefix to discover the Personal Namespaces of other 3056 users that are available to the currently authenticated user. 3058 In response to such a LIST command, a server SHOULD NOT return user 3059 names that have not granted access to their personal mailboxes to the 3060 user in question. 3062 A server MAY return a LIST response containing only the names of 3063 users that have explicitly granted access to the user in question. 3065 Alternatively, a server MAY return NO to such a LIST command, 3066 requiring that a user name be included with the Other Users' 3067 Namespace prefix before listing any other user's mailboxes. 3069 Example 7: 3071 A server that supports providing a list of other user's mailboxes 3072 that are accessible to the currently logged on user. 3074 C: A001 NAMESPACE 3075 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 3076 S: A001 OK NAMESPACE command completed 3078 C: A002 LIST "" "Other Users/%" 3079 S: * LIST () "/" "Other Users/Mike" 3080 S: * LIST () "/" "Other Users/Karen" 3081 S: * LIST () "/" "Other Users/Matthew" 3082 S: * LIST () "/" "Other Users/Tesa" 3083 S: A002 OK LIST command completed 3085 Example 8: 3087 A server that does not support providing a list of other user's 3088 mailboxes that are accessible to the currently logged on user. The 3089 mailboxes are listable if the client includes the name of the other 3090 user with the Other Users' Namespace prefix. 3092 C: A001 NAMESPACE 3093 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 3094 S: A001 OK NAMESPACE command completed 3096 < In this example, the currently logged on user has access to 3097 the Personal Namespace of user Mike, but the server chose to 3098 suppress this information in the LIST response. However, 3099 by appending the user name Mike (received through user input) 3100 to the Other Users' Namespace prefix, the client is able 3101 to get a listing of the personal mailboxes of user Mike. > 3103 C: A002 LIST "" "#Users/%" 3104 S: A002 NO The requested item could not be found. 3106 C: A003 LIST "" "#Users/Mike/%" 3107 S: * LIST () "/" "#Users/Mike/INBOX" 3108 S: * LIST () "/" "#Users/Mike/Foo" 3109 S: A003 OK LIST command completed. 3111 A prefix string might not contain a hierarchy delimiter, because in 3112 some cases it is not needed as part of the prefix. 3114 Example 9: 3116 A server that allows access to the Other Users' Namespace by 3117 prefixing the others' mailboxes with a '~' followed by , 3118 where is a user name as per the LOGIN or AUTHENTICATE 3119 command. 3121 C: A001 NAMESPACE 3122 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 3123 S: A001 OK NAMESPACE command completed 3125 < List the mailboxes for user mark > 3127 C: A002 LIST "" "~mark/%" 3128 S: * LIST () "/" "~mark/INBOX" 3129 S: * LIST () "/" "~mark/foo" 3130 S: A002 OK LIST command completed 3132 6.3.11. STATUS Command 3134 Arguments: mailbox name 3135 status data item names 3137 Responses: REQUIRED untagged responses: STATUS 3139 Result: OK - status completed 3140 NO - status failure: no status for that name 3141 BAD - command unknown or arguments invalid 3143 The STATUS command requests the status of the indicated mailbox. It 3144 does not change the currently selected mailbox, nor does it affect 3145 the state of any messages in the queried mailbox. 3147 The STATUS command provides an alternative to opening a second 3148 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3149 query that mailbox's status without deselecting the current mailbox 3150 in the first IMAP4rev2 connection. 3152 Unlike the LIST command, the STATUS command is not guaranteed to be 3153 fast in its response. Under certain circumstances, it can be quite 3154 slow. In some implementations, the server is obliged to open the 3155 mailbox read-only internally to obtain certain status information. 3156 Also unlike the LIST command, the STATUS command does not accept 3157 wildcards. 3159 Note: The STATUS command is intended to access the status of 3160 mailboxes other than the currently selected mailbox. Because the 3161 STATUS command can cause the mailbox to be opened internally, and 3162 because this information is available by other means on the 3163 selected mailbox, the STATUS command SHOULD NOT be used on the 3164 currently selected mailbox. However, servers MUST be able to 3165 execute STATUS command on the selected mailbox. (This might also 3166 implicitly happen when STATUS return option is used in a LIST 3167 command). 3169 The STATUS command MUST NOT be used as a "check for new messages 3170 in the selected mailbox" operation (refer to Section 7 and 3171 Section 7.4.1 for more information about the proper method for new 3172 message checking). 3174 STATUS SIZE (see below) can take a significant amount of time, 3175 depending upon server implementation. Clients should use STATUS 3176 SIZE cautiously. 3178 The currently defined status data items that can be requested are: 3180 MESSAGES The number of messages in the mailbox. 3182 UIDNEXT The next unique identifier value of the mailbox. Refer to 3183 Section 2.3.1.1 for more information. 3185 UIDVALIDITY The unique identifier validity value of the mailbox. 3186 Refer to Section 2.3.1.1 for more information. 3188 UNSEEN The number of messages which do not have the \Seen flag set. 3190 DELETED The number of messages which have the \Deleted flag set. 3192 SIZE The total size of the mailbox in octets. This is not strictly 3193 required to be an exact value, but it MUST be equal to or greater 3194 than the sum of the values of the RFC822.SIZE FETCH message data 3195 items (see Section 6.4.5) of all messages in the mailbox. 3197 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3198 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3199 S: A042 OK STATUS completed 3201 6.3.12. APPEND Command 3203 Arguments: mailbox name 3204 OPTIONAL flag parenthesized list 3205 OPTIONAL date/time string 3206 message literal 3208 Responses: OPTIONAL untagged response: LIST 3210 Result: OK - append completed 3211 NO - append error: can't append to that mailbox, error 3212 in flags or date/time or message text 3213 BAD - command unknown or arguments invalid 3215 The APPEND command appends the literal argument as a new message to 3216 the end of the specified destination mailbox. This argument SHOULD 3217 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3218 characters are permitted in the message. A server implementation 3219 that is unable to preserve 8-bit data properly MUST be able to 3220 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3221 content transfer encoding. 3223 Note: There may be exceptions, e.g., draft messages, in which 3224 required [RFC-5322] header fields are omitted in the message 3225 literal argument to APPEND. The full implications of doing so 3226 must be understood and carefully weighed. 3228 If a flag parenthesized list is specified, the flags SHOULD be set in 3229 the resulting message; otherwise, the flag list of the resulting 3230 message is set to empty by default. 3232 If a date-time is specified, the internal date SHOULD be set in the 3233 resulting message; otherwise, the internal date of the resulting 3234 message is set to the current date and time by default. 3236 If the append is unsuccessful for any reason, the mailbox MUST be 3237 restored to its state before the APPEND attempt (other than possibly 3238 keeping the changed mailbox's UIDNEXT value); no partial appending is 3239 permitted. 3241 If the destination mailbox does not exist, a server MUST return an 3242 error, and MUST NOT automatically create the mailbox. Unless it is 3243 certain that the destination mailbox can not be created, the server 3244 MUST send the response code "[TRYCREATE]" as the prefix of the text 3245 of the tagged NO response. This gives a hint to the client that it 3246 can attempt a CREATE command and retry the APPEND if the CREATE is 3247 successful. 3249 On successful completion of an APPEND, the server returns an 3250 APPENDUID response code (see Section 7.1), unless specified otherwise 3251 below. 3253 In the case of a mailbox that has permissions set so that the client 3254 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3255 MUST NOT send an APPENDUID response code as it would disclose 3256 information about the mailbox. 3258 In the case of a mailbox that has UIDNOTSTICKY status (see 3259 Section 7.1), the server MAY omit the APPENDUID response code as it 3260 is not meaningful. 3262 If the mailbox is currently selected, the normal new message actions 3263 SHOULD occur. Specifically, the server SHOULD notify the client 3264 immediately via an untagged EXISTS response. If the server does not 3265 do so, the client MAY issue a NOOP command after one or more APPEND 3266 commands. 3268 If the server decides to convert (normalize) the mailbox name, it 3269 SHOULD return an untagged LIST with OLDNAME extended data item, with 3270 the OLDNAME value being the supplied mailbox name and the name 3271 parameter being the normalized mailbox name. (See Section 6.3.9.7 3272 for more details.) 3274 Example: C: A003 APPEND saved-messages (\Seen) {310} 3275 S: + Ready for literal data 3276 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3277 C: From: Fred Foobar 3278 C: Subject: afternoon meeting 3279 C: To: mooch@owatagu.siam.edu 3280 C: Message-Id: 3281 C: MIME-Version: 1.0 3282 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3283 C: 3284 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3285 C: 3286 S: A003 OK APPEND completed 3288 Example: C: A003 APPEND saved-messages (\Seen) {297} 3289 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3290 C: From: Fred Foobar 3291 C: Subject: afternoon meeting 3292 C: To: mooch@example.com 3293 C: Message-Id: 3294 C: MIME-Version: 1.0 3295 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3296 C: 3297 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3298 C: 3299 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3300 C: A004 COPY 2:4 meeting 3301 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3302 C: A005 UID COPY 305:310 meeting 3303 S: A005 OK No matching messages, so nothing copied 3304 C: A006 COPY 2 funny 3305 S: A006 OK Done 3306 C: A007 SELECT funny 3307 S: * 1 EXISTS 3308 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3309 S: * OK [UIDNEXT 2] Predicted next UID 3310 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3311 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3312 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3313 S: * LIST () "." funny 3314 S: A007 OK [READ-WRITE] SELECT completed 3316 In this example, A003 and A004 demonstrate successful appending and 3317 copying to a mailbox that returns the UIDs assigned to the messages. 3318 A005 is an example in which no messages were copied; this is because 3319 in A003, we see that message 2 had UID 304, and message 3 had UID 3320 319; therefore, UIDs 305 through 310 do not exist (refer to 3321 Section 2.3.1.1 for further explanation). A006 is an example of a 3322 message being copied that did not return a COPYUID; and, as expected, 3323 A007 shows that the mail store containing that mailbox does not 3324 support persistent UIDs. 3326 Note: The APPEND command is not used for message delivery, because 3327 it does not provide a mechanism to transfer [SMTP] envelope 3328 information. 3330 6.3.13. IDLE Command 3332 Arguments: none 3334 Responses: continuation data will be requested; the client sends the 3335 continuation data "DONE" to end the command 3337 Result: OK - IDLE completed after client sent "DONE" 3338 NO - failure: the server will not allow the IDLE command 3339 at this time 3340 BAD - command unknown or arguments invalid 3342 Without the IDLE command a client would need to poll the server for 3343 changes to the selected mailbox (new mail, deletions, flag changes). 3344 It's often more desirable to have the server transmit updates to the 3345 client in real time. This allows a user to see new mail immediately. 3346 The IDLE command allows a client to tell the server that it's ready 3347 to accept such real-time updates. 3349 The IDLE command is sent from the client to the server when the 3350 client is ready to accept unsolicited update messages. The server 3351 requests a response to the IDLE command using the continuation ("+") 3352 response. The IDLE command remains active until the client responds 3353 to the continuation, and as long as an IDLE command is active, the 3354 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3355 responses at any time. If the server chooses to send unsolicited 3356 FETCH responses, they MUST include UID FETCH item. 3358 The IDLE command is terminated by the receipt of a "DONE" 3359 continuation from the client; such response satisfies the server's 3360 continuation request. At that point, the server MAY send any 3361 remaining queued untagged responses and then MUST immediately send 3362 the tagged response to the IDLE command and prepare to process other 3363 commands. As for other commands, the processing of any new command 3364 may cause the sending of unsolicited untagged responses, subject to 3365 the ambiguity limitations. The client MUST NOT send a command while 3366 the server is waiting for the DONE, since the server will not be able 3367 to distinguish a command from a continuation. 3369 The server MAY consider a client inactive if it has an IDLE command 3370 running, and if such a server has an inactivity timeout it MAY log 3371 the client off implicitly at the end of its timeout period. Because 3372 of that, clients using IDLE are advised to terminate the IDLE and re- 3373 issue it at least every 29 minutes to avoid being logged off. This 3374 still allows a client to receive immediate mailbox updates even 3375 though it need only "poll" at half hour intervals. 3377 Example: C: A001 SELECT INBOX 3378 S: * FLAGS (\Deleted \Seen \Flagged) 3379 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3380 S: * 3 EXISTS 3381 S: * OK [UIDVALIDITY 1] 3382 S: * LIST () "/" INBOX 3383 S: A001 OK [READ-WRITE] SELECT completed 3384 C: A002 IDLE 3385 S: + idling 3386 ...time passes; new mail arrives... 3387 S: * 4 EXISTS 3388 C: DONE 3389 S: A002 OK IDLE terminated 3390 ...another client expunges message 2 now... 3391 C: A003 FETCH 4 ALL 3392 S: * 4 FETCH (...) 3393 S: A003 OK FETCH completed 3394 C: A004 IDLE 3395 S: * 2 EXPUNGE 3396 S: * 3 EXISTS 3397 S: + idling 3398 ...time passes; another client expunges message 3... 3399 S: * 3 EXPUNGE 3400 S: * 2 EXISTS 3401 ...time passes; new mail arrives... 3402 S: * 3 EXISTS 3403 C: DONE 3404 S: A004 OK IDLE terminated 3405 C: A005 FETCH 3 ALL 3406 S: * 3 FETCH (...) 3407 S: A005 OK FETCH completed 3408 C: A006 IDLE 3410 6.4. Client Commands - Selected State 3412 In the selected state, commands that manipulate messages in a mailbox 3413 are permitted. 3415 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3416 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3417 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3418 APPEND), the following commands are valid in the selected state: 3419 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3421 6.4.1. CLOSE Command 3423 Arguments: none 3425 Responses: no specific responses for this command 3427 Result: OK - close completed, now in authenticated state 3428 BAD - command unknown or arguments invalid 3430 The CLOSE command permanently removes all messages that have the 3431 \Deleted flag set from the currently selected mailbox, and returns to 3432 the authenticated state from the selected state. No untagged EXPUNGE 3433 responses are sent. 3435 No messages are removed, and no error is given, if the mailbox is 3436 selected by an EXAMINE command or is otherwise selected read-only. 3438 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3439 MAY be issued without previously issuing a CLOSE command. The 3440 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3441 selected mailbox without doing an expunge. However, when many 3442 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3443 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3444 no untagged EXPUNGE responses (which the client would probably 3445 ignore) are sent. 3447 Example: C: A341 CLOSE 3448 S: A341 OK CLOSE completed 3450 6.4.2. UNSELECT Command 3452 Arguments: none 3454 Responses: no specific responses for this command 3456 Result: OK - unselect completed, now in authenticated state 3457 BAD - no mailbox selected, or argument supplied but none 3458 permitted 3460 The UNSELECT command frees session's resources associated with the 3461 selected mailbox and returns the server to the authenticated state. 3462 This command performs the same actions as CLOSE, except that no 3463 messages are permanently removed from the currently selected mailbox. 3465 Example: C: A342 UNSELECT 3466 S: A342 OK Unselect completed 3468 6.4.3. EXPUNGE Command 3470 Arguments: none 3472 Responses: untagged responses: EXPUNGE 3474 Result: OK - expunge completed 3475 NO - expunge failure: can't expunge (e.g., permission 3476 denied) 3477 BAD - command unknown or arguments invalid 3479 The EXPUNGE command permanently removes all messages that have the 3480 \Deleted flag set from the currently selected mailbox. Before 3481 returning an OK to the client, an untagged EXPUNGE response is sent 3482 for each message that is removed. 3484 Example: C: A202 EXPUNGE 3485 S: * 3 EXPUNGE 3486 S: * 3 EXPUNGE 3487 S: * 5 EXPUNGE 3488 S: * 8 EXPUNGE 3489 S: A202 OK EXPUNGE completed 3491 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3492 set. See the description of the EXPUNGE response (Section 7.5.1) for 3493 further explanation. 3495 6.4.4. SEARCH Command 3497 Arguments: OPTIONAL result specifier 3498 OPTIONAL [CHARSET] specification 3499 searching criteria (one or more) 3501 Responses: OPTIONAL untagged response: ESEARCH 3503 Result: OK - search completed 3504 NO - search error: can't search that [CHARSET] or 3505 criteria 3506 BAD - command unknown or arguments invalid 3508 The SEARCH command searches the mailbox for messages that match the 3509 given searching criteria. 3511 The SEARCH command may contain result options. Result options 3512 control what kind of information is returned about messages matching 3513 the search criteria in an untagged ESEARCH response. If no result 3514 option is specified or empty list of options is specified "()", ALL 3515 is assumed (see below). The order of individual options is 3516 arbitrary. Individual options may contain parameters enclosed in 3517 parentheses. (However, if an option has a mandatory parameter, which 3518 can always be represented as a number or a sequence-set, the option 3519 parameter does not need the enclosing parentheses. See the Formal 3520 Syntax (Section 9) for more details). If an option has parameters, 3521 they consist of atoms and/or strings and/or lists in a specific 3522 order. Any options not defined by extensions that the server 3523 supports MUST be rejected with a BAD response. 3525 This document specifies the following result options: 3527 MIN 3529 Return the lowest message number/UID that satisfies the SEARCH 3530 criteria. 3532 If the SEARCH results in no matches, the server MUST NOT 3533 include the MIN result option in the ESEARCH response; however, 3534 it still MUST send the ESEARCH response. 3536 MAX 3538 Return the highest message number/UID that satisfies the SEARCH 3539 criteria. 3541 If the SEARCH results in no matches, the server MUST NOT 3542 include the MAX result option in the ESEARCH response; however, 3543 it still MUST send the ESEARCH response. 3545 ALL 3547 Return all message numbers/UIDs that satisfy the SEARCH 3548 criteria using the sequence-set syntax. Note, the client MUST 3549 NOT assume that messages/UIDs will be listed in any particular 3550 order. 3552 If the SEARCH results in no matches, the server MUST NOT 3553 include the ALL result option in the ESEARCH response; however, 3554 it still MUST send the ESEARCH response. 3556 COUNT Return the number of messages that satisfy the SEARCH 3557 criteria. This result option MUST always be included in the 3558 ESEARCH response. 3560 SAVE 3562 This option tells the server to remember the result of the 3563 SEARCH or UID SEARCH command (as well as any command based on 3564 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3565 internal variable that we will reference as the "search result 3566 variable". The client can use the "$" marker to reference the 3567 content of this internal variable. The "$" marker can be used 3568 instead of message sequence or UID sequence in order to 3569 indicate that the server should substitute it with the list of 3570 messages from the search result variable. Thus, the client can 3571 use the result of the latest remembered SEARCH command as a 3572 parameter to another command. See Section 6.4.4.1 for details 3573 on how the value of the search result variable is determined, 3574 how it is affected by other commands executed, and how SAVE 3575 return option interacts with other return options. 3577 In absence of any other SEARCH result option, the SAVE result 3578 option also suppresses any ESEARCH response that would have 3579 been otherwise returned by the SEARCH command. 3581 Note: future extensions to this document can allow servers to return 3582 multiple ESEARCH responses for a single extended SEARCH command. 3583 However all options specified above MUST result in a single ESEARCH 3584 response if used by themselves or in combination. This guaranty 3585 simplifies processing in IMAP4rev2 clients. Future SEARCH extensions 3586 that relax this restriction will have to describe how results from 3587 multiple ESEARCH responses are to be combined. 3589 Searching criteria consist of one or more search keys. 3591 When multiple keys are specified, the result is the intersection (AND 3592 function) of all the messages that match those keys. For example, 3593 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3594 deleted messages from Smith with INTERNALDATE greater than February 3595 1, 1994. A search key can also be a parenthesized list of one or 3596 more search keys (e.g., for use with the OR and NOT keys). 3598 Server implementations MAY exclude [MIME-IMB] body parts with 3599 terminal content media types other than TEXT and MESSAGE from 3600 consideration in SEARCH matching. 3602 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3603 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3604 [CHARSET] of the strings that appear in the search criteria. 3605 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3606 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3607 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3608 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3609 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3610 CHARSET UTF-8 is redundant. It is permitted for improved 3611 compatibility with existing IMAP4rev1 clients. 3613 If the server does not support the specified [CHARSET], it MUST 3614 return a tagged NO response (not a BAD). This response SHOULD 3615 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3616 supported by the server. 3618 In all search keys that use strings and unless specified otherwise, a 3619 message matches the key if the string is a substring of the 3620 associated text. The matching SHOULD be case-insensitive for 3621 characters within ASCII range. Consider using [IMAP-I18N] for 3622 language-sensitive case-insensitive searching. Note that the empty 3623 string is a substring; this is useful when doing a HEADER search in 3624 order to test for a header field presence in the message. 3626 The defined search keys are as follows. Refer to the Formal Syntax 3627 section for the precise syntactic definitions of the arguments. 3629 Messages with message sequence numbers corresponding 3630 to the specified message sequence number set. 3632 ALL All messages in the mailbox; the default initial key for ANDing. 3634 ANSWERED Messages with the \Answered flag set. 3636 BCC Messages that contain the specified string in the 3637 envelope structure's BCC field. 3639 BEFORE Messages whose internal date (disregarding time and 3640 timezone) is earlier than the specified date. 3642 BODY Messages that contain the specified string in the body 3643 of the message. Unlike TEXT (see below), this doesn't match any 3644 header fields. Servers are allowed to implement flexible matching 3645 for this search key, for example matching "swim" to both "swam" 3646 and "swum" in English language text or only doing full word 3647 matching (where "swim" will not match "swimming"). 3649 CC Messages that contain the specified string in the 3650 envelope structure's CC field. 3652 DELETED Messages with the \Deleted flag set. 3654 DRAFT Messages with the \Draft flag set. 3656 FLAGGED Messages with the \Flagged flag set. 3658 FROM Messages that contain the specified string in the 3659 envelope structure's FROM field. 3661 HEADER Messages that have a header field with 3662 the specified field-name (as defined in [RFC-5322]) and that 3663 contains the specified string in the text of the header field 3664 (what comes after the colon). If the string to search is zero- 3665 length, this matches all messages that have a header field with 3666 the specified field-name regardless of the contents. Servers 3667 should use substring search for this SEARCH item, as clients can 3668 use it for automatic processing not initiated by end users. For 3669 example this can be used for searching for Message-ID or Content- 3670 Type header field values that need to be exact, or for searches in 3671 header fields that the IMAP server might not know anything about. 3673 KEYWORD Messages with the specified keyword flag set. 3675 LARGER Messages with an [RFC-5322] size larger than the 3676 specified number of octets. 3678 NOT Messages that do not match the specified search 3679 key. 3681 ON Messages whose internal date (disregarding time and 3682 timezone) is within the specified date. 3684 OR Messages that match either search 3685 key. 3687 SEEN Messages that have the \Seen flag set. 3689 SENTBEFORE Messages whose [RFC-5322] Date: header field 3690 (disregarding time and timezone) is earlier than the specified 3691 date. 3693 SENTON Messages whose [RFC-5322] Date: header field 3694 (disregarding time and timezone) is within the specified date. 3696 SENTSINCE Messages whose [RFC-5322] Date: header field 3697 (disregarding time and timezone) is within or later than the 3698 specified date. 3700 SINCE Messages whose internal date (disregarding time and 3701 timezone) is within or later than the specified date. 3703 SMALLER Messages with an [RFC-5322] size smaller than the 3704 specified number of octets. 3706 SUBJECT Messages that contain the specified string in the 3707 envelope structure's SUBJECT field. 3709 TEXT Messages that contain the specified string in the 3710 header (including MIME header fields) or body of the message. 3711 Servers are allowed to implement flexible matching for this search 3712 key, for example matching "swim" to both "swam" and "swum" in 3713 English language text or only doing full word matching (where 3714 "swim" will not match "swimming"). 3716 TO Messages that contain the specified string in the 3717 envelope structure's TO field. 3719 UID Messages with unique identifiers corresponding to 3720 the specified unique identifier set. Sequence set ranges are 3721 permitted. 3723 UNANSWERED Messages that do not have the \Answered flag set. 3725 UNDELETED Messages that do not have the \Deleted flag set. 3727 UNDRAFT Messages that do not have the \Draft flag set. 3729 UNFLAGGED Messages that do not have the \Flagged flag set. 3731 UNKEYWORD Messages that do not have the specified keyword 3732 flag set. 3734 UNSEEN Messages that do not have the \Seen flag set. 3736 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3737 SINCE 1-Feb-1994 NOT FROM "Smith" 3738 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3739 S: A282 OK SEARCH completed 3741 Example: C: A283 SEARCH RETURN () FLAGGED 3742 SINCE 1-Feb-1994 NOT FROM "Smith" 3743 S: * ESEARCH (TAG "A283") ALL 2,10:11 3744 S: A283 OK SEARCH completed 3746 Example: C: A284 SEARCH TEXT "string not in mailbox" 3747 S: * ESEARCH (TAG "A284") 3748 S: A284 OK SEARCH completed 3749 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3750 S: + Ready for literal text 3751 C: XXXXXX 3752 S: * ESEARCH (TAG "A285") ALL 43 3753 S: A285 OK SEARCH completed 3755 Note: Since this document is restricted to 7-bit ASCII text, it is 3756 not possible to show actual UTF-8 data. The "XXXXXX" is a 3757 placeholder for what would be 6 octets of 8-bit data in an actual 3758 transaction. 3760 The following example demonstrates finding the first unseen message 3761 in the mailbox: 3763 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3764 S: * ESEARCH (TAG "A284") MIN 4 3765 S: A284 OK SEARCH completed 3767 The following example demonstrates that if the ESEARCH UID indicator 3768 is present, all data in the ESEARCH response is referring to UIDs; 3769 for example, the MIN result specifier will be followed by a UID. 3771 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3772 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3773 S: A285 OK SEARCH completed 3775 The following example demonstrates returning the number of deleted 3776 messages: 3778 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3779 S: * ESEARCH (TAG "A286") COUNT 15 3780 S: A286 OK SEARCH completed 3782 6.4.4.1. SAVE result option and SEARCH result variable 3784 Upon successful completion of a SELECT or an EXAMINE command (after 3785 the tagged OK response), the current search result variable is reset 3786 to the empty sequence. 3788 A successful SEARCH command with the SAVE result option sets the 3789 value of the search result variable to the list of messages found in 3790 the SEARCH command. For example, if no messages were found, the 3791 search result variable will contain the empty sequence. 3793 Any of the following SEARCH commands MUST NOT change the search 3794 result variable: 3796 a SEARCH command that caused the server to return the BAD tagged 3797 response, 3799 a SEARCH command with no SAVE result option that caused the server 3800 to return NO tagged response, 3802 a successful SEARCH command with no SAVE result option. 3804 A SEARCH command with the SAVE result option that caused the server 3805 to return the NO tagged response sets the value of the search result 3806 variable to the empty sequence. 3808 When a message listed in the search result variable is EXPUNGEd, it 3809 is automatically removed from the list. Implementors are reminded 3810 that if the server stores the list as a list of message numbers, it 3811 MUST automatically adjust them when notifying the client about 3812 expunged messages, as described in Section 7.5.1. 3814 If the server decides to send a new UIDVALIDITY value while the 3815 mailbox is opened, this causes resetting of the search variable to 3816 the empty sequence. 3818 Note that even if the "$" marker contains the empty sequence of 3819 messages, it must be treated by all commands accepting message sets 3820 as parameters as a valid, but non-matching list of messages. For 3821 example, the "FETCH $" command would return a tagged OK response and 3822 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3824 The SAVE result option doesn't change whether the server would return 3825 items corresponding to MIN, MAX, ALL, or COUNT result options. 3827 When the SAVE result option is combined with the MIN or MAX result 3828 option, and both ALL and COUNT result options are absent, the 3829 corresponding MIN/MAX is returned (if the search result is not 3830 empty), but the "$" marker would contain a single message as returned 3831 in the MIN/MAX return item. 3833 If the SAVE result option is combined with both MIN and MAX result 3834 options, and both ALL and COUNT result options are absent, the "$" 3835 marker would contain zero, one or two messages as returned in the 3836 MIN/MAX return items. 3838 If the SAVE result option is combined with the ALL and/or COUNT 3839 result option(s), the "$" marker would always contain all messages 3840 found by the SEARCH or UID SEARCH command. 3842 The following table summarizes the additional requirement on ESEARCH 3843 server implementations described in this section. 3845 +------------------------------+--------------------+ 3846 | Combination of Result option | "$" marker value | 3847 +------------------------------+--------------------+ 3848 | SAVE MIN | MIN | 3849 | SAVE MAX | MAX | 3850 | SAVE MIN MAX | MIN & MAX | 3851 | SAVE * [m] | all found messages | 3852 +------------------------------+--------------------+ 3854 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3855 and/or "MAX" 3857 Implementation note: server implementors should note that "$" can 3858 reference IMAP message sequences or UID sequences, depending on the 3859 context where it is used. For example, the "$" marker can be set as 3860 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3861 FETCH command (which accepts a UID sequence, not a message sequence), 3862 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3863 command and used as a parameter to a FETCH command (which accepts a 3864 message sequence, not a UID sequence). Server implementations need 3865 to automatically map the "$" marker value to message numbers or UIDs, 3866 depending on context where the "$" marker is used. 3868 6.4.4.2. Multiple Commands in Progress 3870 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3871 "$" marker creates direct dependency between the two commands. As 3872 directed by Section 5.5, a server MUST execute the two commands in 3873 the order they were received. 3875 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3876 command using the "$" marker, as long as this doesn't create an 3877 ambiguity, as described in Section 5.5. Examples 7-9 in 3878 Section 6.4.4.4 explain this in more details. 3880 6.4.4.3. Refusing to Save Search Results 3882 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3883 for example, if an internal limit on the number of saved results is 3884 reached. In this case, the server MUST return a tagged NO response 3885 containing the NOTSAVED response code and set the search result 3886 variable to the empty sequence, as described in Section 6.4.4.1. 3888 6.4.4.4. Examples showing use of SAVE result option 3890 Only in this section: explanatory comments in examples that start 3891 with // are not part of the protocol. 3893 1) The following example demonstrates how the client can use the 3894 result of a SEARCH command to FETCH headers of interesting messages: 3896 Example 1: 3897 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3898 NOT FROM "Smith" 3899 S: A282 OK SEARCH completed, result saved 3900 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3901 S: * 2 FETCH (UID 14 ... 3902 S: * 84 FETCH (UID 100 ... 3903 S: * 882 FETCH (UID 1115 ... 3904 S: A283 OK completed 3906 The client can also pipeline the two commands: 3908 Example 2: 3909 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3910 NOT FROM "Smith" 3911 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3912 S: A282 OK SEARCH completed 3913 S: * 2 FETCH (UID 14 ... 3914 S: * 84 FETCH (UID 100 ... 3915 S: * 882 FETCH (UID 1115 ... 3916 S: A283 OK completed 3918 2) The following example demonstrates that the result of one SEARCH 3919 command can be used as input to another SEARCH command: 3921 Example 3: 3922 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3923 NOT FROM "Smith" 3924 S: A300 OK SEARCH completed 3925 C: A301 UID SEARCH UID $ SMALLER 4096 3926 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3927 S: A301 OK completed 3929 Note that the second command in Example 3 can be replaced with: 3930 C: A301 UID SEARCH $ SMALLER 4096 3931 and the result of the command would be the same. 3933 3) The following example shows that the "$" marker can be combined 3934 with other message numbers using the OR SEARCH criterion. 3936 Example 4: 3937 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3938 NOT FROM "Smith" 3939 S: P282 OK SEARCH completed 3940 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3941 C: YYYYYYYY 3942 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3943 S: P283 OK completed 3945 Note: Since this document format is restricted to 7-bit ASCII text, 3946 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3947 placeholder for what would be 8 octets of 8-bit data in an actual 3948 transaction. 3950 4) The following example demonstrates that a failed SEARCH sets the 3951 search result variable to the empty list. The server doesn't 3952 implement the KOI8-R charset. 3954 Example 5: 3955 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3956 NOT FROM "Smith" 3957 S: B282 OK SEARCH completed 3958 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3959 (OR $ 1,3000:3021) TEXT {4} 3960 C: XXXX 3961 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3962 //After this command the saved result variable contains 3963 //no messages. A client that wants to reissue the B283 3964 //SEARCH command with another CHARSET would have to reissue 3965 //the B282 command as well. One possible workaround for 3966 //this is to include the desired CHARSET parameter 3967 //in the earliest SEARCH RETURN (SAVE) command in a 3968 //sequence of related SEARCH commands, to cause 3969 //the earliest SEARCH in the sequence to fail. 3970 //A better approach might be to always use CHARSET UTF-8 3971 //instead. 3973 Note: Since this document format is restricted to 7-bit ASCII text, 3974 it is not possible to show actual KOI8-R data. The "XXXX" is a 3975 placeholder for what would be 4 octets of 8-bit data in an actual 3976 transaction. 3978 5) The following example demonstrates that it is not an error to use 3979 the "$" marker when it contains no messages. 3981 Example 6: 3982 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3983 NOT FROM "Eric" 3984 C: E283 COPY $ "Other Messages" 3985 //The "$" contains no messages 3986 S: E282 OK SEARCH completed 3987 S: E283 OK COPY completed, nothing copied 3989 Example 7: 3990 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3991 C: F283 COPY $ "Junk" 3992 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3993 S: F282 OK SEARCH completed 3994 S: F283 OK COPY completed 3995 S: F284 OK STORE completed 3997 Example 8: 3998 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3999 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 4000 FROM "Eric" 4001 // The server can execute the two SEARCH commands 4002 // in any order, as they don't have any dependency. 4003 // For example, it may return: 4004 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 4005 S: G283 OK SEARCH completed 4006 S: G282 OK SEARCH completed 4008 The following example demonstrates that the result of the second 4009 SEARCH RETURN (SAVE) always overrides the result of the first. 4011 Example 9: 4012 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 4013 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 4014 FROM "Eric" 4015 S: H282 OK SEARCH completed 4016 S: H283 OK SEARCH completed 4017 // At this point "$" would contain results of H283 4019 The following example demonstrates behavioral difference for 4020 different combinations of ESEARCH result options. 4022 Example 10: 4023 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 4024 NOT FROM "Smith" 4025 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 4026 //$ value hasn't changed 4027 S: C282 OK SEARCH completed 4029 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 4030 NOT FROM "Smith" 4031 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 4032 //$ value is 2,10:15,21 4033 S: C283 OK SEARCH completed 4035 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 4036 NOT FROM "Smith" 4037 S: * ESEARCH (TAG "C284") MIN 2 4038 //$ value is 2 4039 S: C284 OK SEARCH completed 4041 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 4042 12-Feb-2006 NOT FROM "Smith" 4043 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 4044 //$ value is 2,21 4045 S: C285 OK SEARCH completed 4047 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 4048 SINCE 12-Feb-2006 NOT FROM "Smith" 4049 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 4050 //$ value is 2,10:15,21 4051 S: C286 OK SEARCH completed 4053 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 4054 12-Feb-2006 NOT FROM "Smith" 4055 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 4056 //$ value is 2,10:15,21 4057 S: C286 OK SEARCH completed 4059 6.4.5. FETCH Command 4061 Arguments: sequence set 4062 message data item names or macro 4064 Responses: untagged responses: FETCH 4066 Result: OK - fetch completed 4067 NO - fetch error: can't fetch that data 4068 BAD - command unknown or arguments invalid 4070 The FETCH command retrieves data associated with a message in the 4071 mailbox. The data items to be fetched can be either a single atom or 4072 a parenthesized list. 4074 Most data items, identified in the formal syntax (Section 9) under 4075 the msg-att-static rule, are static and MUST NOT change for any 4076 particular message. Other data items, identified in the formal 4077 syntax under the msg-att-dynamic rule, MAY change, either as a result 4078 of a STORE command or due to external events. 4080 For example, if a client receives an ENVELOPE for a message when 4081 it already knows the envelope, it can safely ignore the newly 4082 transmitted envelope. 4084 There are three macros which specify commonly-used sets of data 4085 items, and can be used instead of data items. A macro must be used 4086 by itself, and not in conjunction with other macros or data items. 4088 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 4090 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 4092 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 4093 BODY) 4095 Several data items reference "section" or "section-binary". See 4096 Section 6.4.5.1 for their detailed definition. 4098 The currently defined data items that can be fetched are: 4100 BINARY[]<> 4102 Requests that the specified section be transmitted after 4103 performing Content-Transfer-Encoding-related decoding. 4105 The argument, if present, requests that a subset of 4106 the data be returned. The semantics of a partial FETCH BINARY 4107 command are the same as for a partial FETCH BODY command, with 4108 the exception that the arguments refer to the DECODED 4109 section data. 4111 Note that this data item can only be requested for leaf (i.e. 4112 non multipart/*, non message/rfc822 and non message/global) 4113 body parts. 4115 BINARY.PEEK[]<> An alternate form of 4116 BINARY[] that does not implicitly set the \Seen 4117 flag. 4119 BINARY.SIZE[] 4121 Requests the decoded size of the section (i.e., the size to 4122 expect in response to the corresponding FETCH BINARY request). 4124 Note: client authors are cautioned that this might be an 4125 expensive operation for some server implementations. 4126 Needlessly issuing this request could result in degraded 4127 performance due to servers having to calculate the value every 4128 time the request is issued. 4130 Note that this data item can only be requested for leaf (i.e. 4131 non multipart/*, non message/rfc822 and non message/global) 4132 body parts. 4134 BODY Non-extensible form of BODYSTRUCTURE. 4136 BODY[
]<> 4138 The text of a particular body section. 4140 It is possible to fetch a substring of the designated text. 4141 This is done by appending an open angle bracket ("<"), the 4142 octet position of the first desired octet, a period, the 4143 maximum number of octets desired, and a close angle bracket 4144 (">") to the part specifier. If the starting octet is beyond 4145 the end of the text, an empty string is returned. 4147 Any partial fetch that attempts to read beyond the end of the 4148 text is truncated as appropriate. A partial fetch that starts 4149 at octet 0 is returned as a partial fetch, even if this 4150 truncation happened. 4152 Note: This means that BODY[]<0.2048> of a 1500-octet message 4153 will return BODY[]<0> with a literal of size 1500, not 4154 BODY[]. 4156 Note: A substring fetch of a HEADER.FIELDS or 4157 HEADER.FIELDS.NOT part specifier is calculated after 4158 subsetting the header. 4160 The \Seen flag is implicitly set; if this causes the flags to 4161 change, they SHOULD be included as part of the FETCH responses. 4163 BODY.PEEK[
]<> An alternate form of BODY[
] 4164 that does not implicitly set the \Seen flag. 4166 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4167 computed by the server by parsing the [MIME-IMB] header fields in 4168 the [RFC-5322] header and [MIME-IMB] headers. See Section 7.5.2 4169 for more details. 4171 ENVELOPE The envelope structure of the message. This is computed by 4172 the server by parsing the [RFC-5322] header into the component 4173 parts, defaulting various fields as necessary. See Section 7.5.2 4174 for more details. 4176 FLAGS The flags that are set for this message. 4178 INTERNALDATE The internal date of the message. 4180 RFC822.SIZE The [RFC-5322] size of the message. 4182 UID The unique identifier for the message. 4184 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4185 S: * 2 FETCH .... 4186 S: * 3 FETCH .... 4187 S: * 4 FETCH .... 4188 S: A654 OK FETCH completed 4190 6.4.5.1. FETCH section specification 4192 Several FETCH data items reference "section" or "section-binary". 4193 The section specification is a set of zero or more part specifiers 4194 delimited by periods. A part specifier is either a part number or 4195 one of the following: HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, 4196 and TEXT. (Non numeric part specifiers have to be the last specifier 4197 in a section specification.) An empty section specification refers 4198 to the entire message, including the header. 4200 Every message has at least one part number. Non-[MIME-IMB] messages, 4201 and non-multipart [MIME-IMB] messages with no encapsulated message, 4202 only have a part 1. 4204 Multipart messages are assigned consecutive part numbers, as they 4205 occur in the message. If a particular part is of type message or 4206 multipart, its parts MUST be indicated by a period followed by the 4207 part number within that nested multipart part. 4209 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested part 4210 numbers, referring to parts of the MESSAGE part's body. 4212 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 4213 specifiers can be the sole part specifier or can be prefixed by one 4214 or more numeric part specifiers, provided that the numeric part 4215 specifier refers to a part of type MESSAGE/RFC822 or MESSAGE/GLOBAL. 4216 The MIME part specifier MUST be prefixed by one or more numeric part 4217 specifiers. 4219 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part specifiers 4220 refer to the [RFC-5322] header of the message or of an encapsulated 4221 [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL message. HEADER.FIELDS 4222 and HEADER.FIELDS.NOT are followed by a list of field-name (as 4223 defined in [RFC-5322]) names, and return a subset of the header. The 4224 subset returned by HEADER.FIELDS contains only those header fields 4225 with a field-name that matches one of the names in the list; 4226 similarly, the subset returned by HEADER.FIELDS.NOT contains only the 4227 header fields with a non-matching field-name. The field-matching is 4228 ASCII range case-insensitive but otherwise exact. Subsetting does 4229 not exclude the [RFC-5322] delimiting blank line between the header 4230 and the body; the blank line is included in all header fetches, 4231 except in the case of a message which has no body and no blank line. 4233 The MIME part specifier refers to the [MIME-IMB] header for this 4234 part. 4236 The TEXT part specifier refers to the text body of the message, 4237 omitting the [RFC-5322] header. 4239 Here is an example of a complex message with some of its part 4240 specifiers: 4242 HEADER ([RFC-5322] header of the message) 4243 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4244 1 TEXT/PLAIN 4245 2 APPLICATION/OCTET-STREAM 4246 3 MESSAGE/RFC822 4247 3.HEADER ([RFC-5322] header of the message) 4248 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4249 3.1 TEXT/PLAIN 4250 3.2 APPLICATION/OCTET-STREAM 4251 4 MULTIPART/MIXED 4252 4.1 IMAGE/GIF 4253 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4254 4.2 MESSAGE/RFC822 4255 4.2.HEADER ([RFC-5322] header of the message) 4256 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4257 4.2.1 TEXT/PLAIN 4258 4.2.2 MULTIPART/ALTERNATIVE 4259 4.2.2.1 TEXT/PLAIN 4260 4.2.2.2 TEXT/RICHTEXT 4262 6.4.6. STORE Command 4264 Arguments: sequence set 4265 message data item name 4266 value for message data item 4268 Responses: untagged responses: FETCH 4270 Result: OK - store completed 4271 NO - store error: can't store that data 4272 BAD - command unknown or arguments invalid 4274 The STORE command alters data associated with a message in the 4275 mailbox. Normally, STORE will return the updated value of the data 4276 with an untagged FETCH response. A suffix of ".SILENT" in the data 4277 item name prevents the untagged FETCH, and the server SHOULD assume 4278 that the client has determined the updated value itself or does not 4279 care about the updated value. 4281 Note: Regardless of whether or not the ".SILENT" suffix was used, 4282 the server SHOULD send an untagged FETCH response if a change to a 4283 message's flags from an external source is observed. The intent 4284 is that the status of the flags is determinate without a race 4285 condition. 4287 The currently defined data items that can be stored are: 4289 FLAGS Replace the flags for the message with the 4290 argument. The new value of the flags is returned as if a FETCH of 4291 those flags was done. 4293 FLAGS.SILENT Equivalent to FLAGS, but without returning 4294 a new value. 4296 +FLAGS Add the argument to the flags for the message. 4297 The new value of the flags is returned as if a FETCH of those 4298 flags was done. 4300 +FLAGS.SILENT Equivalent to +FLAGS, but without 4301 returning a new value. 4303 -FLAGS Remove the argument from the flags for the 4304 message. The new value of the flags is returned as if a FETCH of 4305 those flags was done. 4307 -FLAGS.SILENT Equivalent to -FLAGS, but without 4308 returning a new value. 4310 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4311 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4312 S: * 3 FETCH (FLAGS (\Deleted)) 4313 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4314 S: A003 OK STORE completed 4316 6.4.7. COPY Command 4318 Arguments: sequence set 4319 mailbox name 4321 Responses: no specific responses for this command 4323 Result: OK - copy completed 4324 NO - copy error: can't copy those messages or to that 4325 name 4326 BAD - command unknown or arguments invalid 4328 The COPY command copies the specified message(s) to the end of the 4329 specified destination mailbox. The flags and internal date of the 4330 message(s) SHOULD be preserved in the copy. 4332 If the destination mailbox does not exist, a server MUST return an 4333 error. It MUST NOT automatically create the mailbox. Unless it is 4334 certain that the destination mailbox can not be created, the server 4335 MUST send the response code "[TRYCREATE]" as the prefix of the text 4336 of the tagged NO response. This gives a hint to the client that it 4337 can attempt a CREATE command and retry the COPY if the CREATE is 4338 successful. 4340 If the COPY command is unsuccessful for any reason, server 4341 implementations MUST restore the destination mailbox to its state 4342 before the COPY attempt (other than possibly incrementing UIDNEXT), 4343 i.e. partial copy MUST NOT be done. 4345 On successful completion of a COPY, the server returns a COPYUID 4346 response code (see Section 7.1). Two exception to this requirement 4347 are listed below. 4349 In the case of a mailbox that has permissions set so that the client 4350 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4351 MUST NOT send an COPYUID response code as it would disclose 4352 information about the mailbox. 4354 In the case of a mailbox that has UIDNOTSTICKY status (see 4355 Section 7.1), the server MAY omit the COPYUID response code as it is 4356 not meaningful. 4358 Example: C: A003 COPY 2:4 MEETING 4359 S: A003 OK [COPYUID 38505 304,319:320 3956:3958] COPY completed 4361 6.4.8. MOVE Command 4363 Arguments: sequence set 4364 mailbox name 4366 Responses: no specific responses for this command 4368 Result: OK - move completed 4369 NO - move error: can't move those messages or to that 4370 name 4371 BAD - command unknown or arguments invalid 4373 The MOVE command moves the specified message(s) to the end of the 4374 specified destination mailbox. The flags and internal date of the 4375 message(s) SHOULD be preserved. 4377 This means that a new message is created in the target mailbox with a 4378 new UID, the original message is removed from the source mailbox, and 4379 it appears to the client as a single action. This has the same 4380 effect for each message as this sequence: 4382 1. [UID] COPY 4384 2. [UID] STORE +FLAGS.SILENT \DELETED 4386 3. UID EXPUNGE 4388 Although the effect of the MOVE is the same as the preceding steps, 4389 the semantics are not identical: The intermediate states produced by 4390 those steps do not occur, and the response codes are different. In 4391 particular, though the COPY and EXPUNGE response codes will be 4392 returned, response codes for a STORE MUST NOT be generated and the 4393 \Deleted flag MUST NOT be set for any message. 4395 Unlike the COPY command, MOVE of a set of messages might fail partway 4396 through the set. Regardless of whether the command is successful in 4397 moving the entire set, each individual message MUST either be moved 4398 or unaffected. The server MUST leave each message in a state where 4399 it is in at least one of the source or target mailboxes (no message 4400 can be lost or orphaned). The server SHOULD NOT leave any message in 4401 both mailboxes (it would be bad for a partial failure to result in a 4402 bunch of duplicate messages). This is true even if the server 4403 returns a tagged NO response to the command. 4405 If the destination mailbox does not exist, a server MUST return an 4406 error. It MUST NOT automatically create the mailbox. Unless it is 4407 certain that the destination mailbox can not be created, the server 4408 MUST send the response code "[TRYCREATE]" as the prefix of the text 4409 of the tagged NO response. This gives a hint to the client that it 4410 can attempt a CREATE command and retry the MOVE if the CREATE is 4411 successful. 4413 Because of the similarity of MOVE to COPY, extensions that affect 4414 COPY affect MOVE in the same way. Response codes listed in 4415 Section 7.1, as well as those defined by extensions, are sent as 4416 appropriate. 4418 Servers send COPYUID in response to a MOVE or a UID MOVE (see 4419 Section 6.4.9) command. For additional information about COPYUID see 4420 Section 7.1. Note that there are several exceptions listed in 4421 Section 6.4.7 that allow servers not to return COPYUID. 4423 Servers are also REQUIRED to send the COPYUID response code in an 4424 untagged OK before sending EXPUNGE or similar responses. (Sending 4425 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4426 means that clients first receive an EXPUNGE for a message and 4427 afterwards COPYUID for the same message. It can be unnecessarily 4428 difficult to process that sequence usefully.) 4430 An example: 4431 C: a UID MOVE 42:69 foo 4432 S: * OK [COPYUID 432432 42:69 1202:1229] 4433 S: * 22 EXPUNGE 4434 ...More EXPUNGE responses from the server... 4435 S: a OK Done 4437 Note that the server may send unrelated EXPUNGE responses as well, if 4438 any happen to have been expunged at the same time; this is normal 4439 IMAP operation. 4441 Note that moving a message to the currently selected mailbox (that 4442 is, where the source and target mailboxes are the same) is allowed 4443 when copying the message to the currently selected mailbox is 4444 allowed. 4446 The server may send EXPUNGE responses before the tagged response, so 4447 the client cannot safely send more commands with message sequence 4448 number arguments while the server is processing MOVE. 4450 MOVE and UID MOVE can be pipelined with other commands, but care has 4451 to be taken. Both commands modify sequence numbers and also allow 4452 unrelated EXPUNGE responses. The renumbering of other messages in 4453 the source mailbox following any EXPUNGE response can be surprising 4454 and makes it unsafe to pipeline any command that relies on message 4455 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4456 pipelined with a command that might cause message renumbering. See 4457 Section 5.5, for more information about ambiguities as well as 4458 handling requirements for both clients and servers. 4460 6.4.9. UID Command 4462 Arguments: command name 4463 command arguments 4465 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4467 Result: OK - UID command completed 4468 NO - UID command error 4469 BAD - command unknown or arguments invalid 4471 The UID command has three forms. In the first form, it takes as its 4472 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4473 appropriate for the associated command. However, the numbers in the 4474 sequence set argument are unique identifiers instead of message 4475 sequence numbers. Sequence set ranges are permitted, but there is no 4476 guarantee that unique identifiers will be contiguous. 4478 A non-existent unique identifier is ignored without any error message 4479 generated. Thus, it is possible for a UID FETCH command to return an 4480 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4481 OK without performing any operations. 4483 In the second form, the UID command takes an EXPUNGE command with an 4484 extra parameter the specified a sequence set of UIDs to operate on. 4485 The UID EXPUNGE command permanently removes all messages that both 4486 have the \Deleted flag set and have a UID that is included in the 4487 specified sequence set from the currently selected mailbox. If a 4488 message either does not have the \Deleted flag set or has a UID that 4489 is not included in the specified sequence set, it is not affected. 4491 UID EXPUNGE is particularly useful for disconnected use clients. 4492 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4493 the server, the client can ensure that it does not inadvertantly 4494 remove any messages that have been marked as \Deleted by other 4495 clients between the time that the client was last connected and 4496 the time the client resynchronizes. 4498 Example: C: A003 UID EXPUNGE 3000:3002 4499 S: * 3 EXPUNGE 4500 S: * 3 EXPUNGE 4501 S: * 3 EXPUNGE 4502 S: A003 OK UID EXPUNGE completed 4504 In the third form, the UID command takes a SEARCH command with SEARCH 4505 command arguments. The interpretation of the arguments is the same 4506 as with SEARCH; however, the numbers returned in a ESEARCH response 4507 for a UID SEARCH command are unique identifiers instead of message 4508 sequence numbers. Also, the corresponding ESEARCH response MUST 4509 include the UID indicator. For example, the command UID SEARCH 1:100 4510 UID 443:557 returns the unique identifiers corresponding to the 4511 intersection of two sequence sets, the message sequence number range 4512 1:100 and the UID range 443:557. 4514 Note: in the above example, the UID range 443:557 appears. The 4515 same comment about a non-existent unique identifier being ignored 4516 without any error message also applies here. Hence, even if 4517 neither UID 443 or 557 exist, this range is valid and would 4518 include an existing UID 495. 4520 Also note that a UID range of 559:* always includes the UID of the 4521 last message in the mailbox, even if 559 is higher than any 4522 assigned UID value. This is because the contents of a range are 4523 independent of the order of the range endpoints. Thus, any UID 4524 range with * as one of the endpoints indicates at least one 4525 message (the message with the highest numbered UID), unless the 4526 mailbox is empty. 4528 The number after the "*" in an untagged FETCH or EXPUNGE response is 4529 always a message sequence number, not a unique identifier, even for a 4530 UID command response. However, server implementations MUST 4531 implicitly include the UID message data item as part of any FETCH 4532 response caused by a UID command, regardless of whether a UID was 4533 specified as a message data item to the FETCH. 4535 Note: The rule about including the UID message data item as part of a 4536 FETCH response primarily applies to the UID FETCH and UID STORE 4537 commands, including a UID FETCH command that does not include UID as 4538 a message data item. Although it is unlikely that the other UID 4539 commands will cause an untagged FETCH, this rule applies to these 4540 commands as well. 4542 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4543 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4544 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4545 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4546 S: A999 OK UID FETCH completed 4548 6.5. Client Commands - Experimental/Expansion 4550 Each command which is not part of this specification MUST have at 4551 least one capability name (see Section 6.1.1) associated with it. 4552 (Multiple commands can be associated with the same capability name) 4554 Server implementations MUST NOT send any added (not specified in this 4555 specification) untagged responses, unless the client requested it by 4556 issuing the associated experimental command or the ENABLE command 4557 (Section 6.3.1). 4559 The following example demonstrates how a client can check for 4560 presence of a fictitious XPIG-LATIN capability that adds the XPIG- 4561 LATIN command and the the XPIG-LATIN untagged response. (Note that 4562 for an extension the command name and the capability name don't have 4563 to be the same.) 4565 Example: C: a441 CAPABILITY 4566 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4567 S: a441 OK CAPABILITY completed 4568 C: A442 XPIG-LATIN 4569 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4570 S: A442 OK XPIG-LATIN ompleted-cay 4572 7. Server Responses 4574 Server responses are in three forms: status responses, server data, 4575 and command continuation request. The information contained in a 4576 server response, identified by "Contents:" in the response 4577 descriptions below, is described by function, not by syntax. The 4578 precise syntax of server responses is described in the Formal Syntax 4579 (Section 9). 4581 The client MUST be prepared to accept any response at all times. 4583 Status responses can be tagged or untagged. Tagged status responses 4584 indicate the completion result (OK, NO, or BAD status) of a client 4585 command, and have a tag matching the command. 4587 Some status responses, and all server data, are untagged. An 4588 untagged response is indicated by the token "*" instead of a tag. 4589 Untagged status responses indicate server greeting, or server status 4590 that does not indicate the completion of a command (for example, an 4591 impending system shutdown alert). For historical reasons, untagged 4592 server data responses are also called "unsolicited data", although 4593 strictly speaking, only unilateral server data is truly 4594 "unsolicited". 4596 Certain server data MUST be remembered by the client when it is 4597 received; this is noted in the description of that data. Such data 4598 conveys critical information which affects the interpretation of all 4599 subsequent commands and responses (e.g., updates reflecting the 4600 creation or destruction of messages). 4602 Other server data SHOULD be remembered for later reference; if the 4603 client does not need to remember the data, or if remembering the data 4604 has no obvious purpose (e.g., a SEARCH response when no SEARCH 4605 command is in progress), the data can be ignored. 4607 An example of unilateral untagged server data occurs when the IMAP 4608 connection is in the selected state. In the selected state, the 4609 server checks the mailbox for new messages as part of command 4610 execution. Normally, this is part of the execution of every command; 4611 hence, a NOOP command suffices to check for new messages. If new 4612 messages are found, the server sends untagged EXISTS response 4613 reflecting the new size of the mailbox. Server implementations that 4614 offer multiple simultaneous access to the same mailbox SHOULD also 4615 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4616 another agent changes the state of any message flags or expunges any 4617 messages. 4619 Command continuation request responses use the token "+" instead of a 4620 tag. These responses are sent by the server to indicate acceptance 4621 of an incomplete client command and readiness for the remainder of 4622 the command. 4624 7.1. Server Responses - Generic Status Responses 4626 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4627 can be tagged or untagged. PREAUTH and BYE are always untagged. 4629 Status responses MAY include an OPTIONAL "response code". A response 4630 code consists of data inside square brackets in the form of an atom, 4631 possibly followed by a space and arguments. The response code 4632 contains additional information or status codes for client software 4633 beyond the OK/NO/BAD condition, and are defined when there is a 4634 specific action that a client can take based upon the additional 4635 information. 4637 The currently defined response codes are: 4639 ALERT 4641 The human-readable text contains a special alert that are 4642 presented to the user in a fashion that calls the user's 4643 attention to the message. Content of ALERT response codes 4644 received on a connection without TLS or SASL security layer 4645 confidentiality SHOULD be ignored by clients. If displayed, 4646 such alerts MUST be clearly marked as potentially suspicious. 4647 (Note that some existing clients are known to hyperlink 4648 returned text which make them very dangerous.) Alerts received 4649 after successful establishment of a TLS/SASL confidentiality 4650 layer MUST be presented to the user. 4652 ALREADYEXISTS 4654 The operation attempts to create something that already exists, 4655 such as when the CREATE or RENAME directories attempt to create 4656 a mailbox and there is already one of that name. 4658 C: o356 RENAME this that 4659 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4661 APPENDUID 4663 Followed by the UIDVALIDITY of the destination mailbox and the 4664 UID assigned to the appended message in the destination 4665 mailbox, indicates that the message has been appended to the 4666 destination mailbox with that UID. 4668 If the server also supports the [MULTIAPPEND] extension, and if 4669 multiple messages were appended in the APPEND command, then the 4670 second value is a UID set containing the UIDs assigned to the 4671 appended messages, in the order they were transmitted in the 4672 APPEND command. This UID set may not contain extraneous UIDs 4673 or the symbol "*". 4675 Note: the UID set form of the APPENDUID response code MUST 4676 NOT be used if only a single message was appended. In 4677 particular, a server MUST NOT send a range such as 123:123. 4678 This is because a client that does not support [MULTIAPPEND] 4679 expects only a single UID and not a UID set. 4681 UIDs are assigned in strictly ascending order in the mailbox 4682 (refer to Section 2.3.1.1); note that a range of 12:10 is 4683 exactly equivalent to 10:12 and refers to the sequence 4684 10,11,12. 4686 This response code is returned in a tagged OK response to the 4687 APPEND command. 4689 AUTHENTICATIONFAILED 4691 Authentication failed for some reason on which the server is 4692 unwilling to elaborate. Typically, this includes "unknown 4693 user" and "bad password". 4695 This is the same as not sending any response code, except that 4696 when a client sees AUTHENTICATIONFAILED, it knows that the 4697 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4698 trying the same login/password again later. 4700 C: b LOGIN "fred" "foo" 4701 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4703 AUTHORIZATIONFAILED 4705 Authentication succeeded in using the authentication identity, 4706 but the server cannot or will not allow the authentication 4707 identity to act as the requested authorization identity. This 4708 is only applicable when the authentication and authorization 4709 identities are different. 4711 C: c1 AUTHENTICATE PLAIN 4712 [...] 4713 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4715 C: c2 AUTHENTICATE PLAIN 4716 [...] 4717 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4719 BADCHARSET 4721 Optionally followed by a parenthesized list of charsets. A 4722 SEARCH failed because the given charset is not supported by 4723 this implementation. If the optional list of charsets is 4724 given, this lists the charsets that are supported by this 4725 implementation. 4727 CANNOT 4729 The operation violates some invariant of the server and can 4730 never succeed. 4732 C: l create "///////" 4733 S: l NO [CANNOT] Adjacent slashes are not supported 4735 CAPABILITY 4737 Followed by a list of capabilities. This can appear in the 4738 initial OK or PREAUTH response to transmit an initial 4739 capabilities list. It can also appear in tagged responses to 4740 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4741 a client to send a separate CAPABILITY command if it recognizes 4742 this response. 4744 CLIENTBUG 4746 The server has detected a client bug. This can accompany all 4747 of OK, NO, and BAD, depending on what the client bug is. 4749 C: k1 select "/archive/projects/experiment-iv" 4750 [...] 4751 S: k1 OK [READ-ONLY] Done 4752 C: k2 status "/archive/projects/experiment-iv" (messages) 4753 [...] 4754 S: k2 OK [CLIENTBUG] Done 4756 CLOSED 4758 The CLOSED response code has no parameters. A server return 4759 the CLOSED response code when the currently selected mailbox is 4760 closed implicitly using the SELECT/EXAMINE command on another 4761 mailbox. The CLOSED response code serves as a boundary between 4762 responses for the previously opened mailbox (which was closed) 4763 and the newly selected mailbox; all responses before the CLOSED 4764 response code relate to the mailbox that was closed, and all 4765 subsequent responses relate to the newly opened mailbox. 4767 There is no need to return the CLOSED response code on 4768 completion of the CLOSE or the UNSELECT command (or similar), 4769 whose purpose is to close the currently selected mailbox 4770 without opening a new one. 4772 CONTACTADMIN 4774 The user should contact the system administrator or support 4775 desk. 4777 C: e login "fred" "foo" 4778 S: e NO [CONTACTADMIN] 4780 COPYUID 4781 Followed by the UIDVALIDITY of the destination mailbox, a UID 4782 set containing the UIDs of the message(s) in the source mailbox 4783 that were copied to the destination mailbox and containing the 4784 UIDs assigned to the copied message(s) in the destination 4785 mailbox, indicates that the message(s) have been copied to the 4786 destination mailbox with the stated UID(s). 4788 The source UID set is in the order the message(s) were copied; 4789 the destination UID set corresponds to the source UID set and 4790 is in the same order. Neither of the UID sets may contain 4791 extraneous UIDs or the symbol "*". 4793 UIDs are assigned in strictly ascending order in the mailbox 4794 (refer to Section 2.3.1.1); note that a range of 12:10 is 4795 exactly equivalent to 10:12 and refers to the sequence 4796 10,11,12. 4798 This response code is returned in a tagged OK response to the 4799 COPY/UID COPY command or in the untagged OK response to the 4800 MOVE/UID MOVE command. 4802 CORRUPTION 4804 The server discovered that some relevant data (e.g., the 4805 mailbox) are corrupt. This response code does not include any 4806 information about what's corrupt, but the server can write that 4807 to its logfiles. 4809 C: i select "/archive/projects/experiment-iv" 4810 S: i NO [CORRUPTION] Cannot open mailbox 4812 EXPIRED 4814 Either authentication succeeded or the server no longer had the 4815 necessary data; either way, access is no longer permitted using 4816 that passphrase. The client or user should get a new 4817 passphrase. 4819 C: d login "fred" "foo" 4820 S: d NO [EXPIRED] That password isn't valid any more 4822 EXPUNGEISSUED 4824 Someone else has issued an EXPUNGE for the same mailbox. The 4825 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4826 discusses this subject in depth. 4828 C: h search from fred@example.com 4829 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4830 S: h OK [EXPUNGEISSUED] Search completed 4832 HASCHILDREN 4834 The mailbox delete operation failed because the mailbox has one 4835 or more children and the server doesn't allow deletion of 4836 mailboxes with children. 4838 C: m356 DELETE Notes 4839 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4840 to be deleted first 4842 INUSE 4844 An operation has not been carried out because it involves 4845 sawing off a branch someone else is sitting on. Someone else 4846 may be holding an exclusive lock needed for this operation, or 4847 the operation may involve deleting a resource someone else is 4848 using, typically a mailbox. 4850 The operation may succeed if the client tries again later. 4852 C: g delete "/archive/projects/experiment-iv" 4853 S: g NO [INUSE] Mailbox in use 4855 LIMIT 4857 The operation ran up against an implementation limit of some 4858 kind, such as the number of flags on a single message or the 4859 number of flags used in a mailbox. 4861 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4862 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4864 NONEXISTENT 4866 The operation attempts to delete something that does not exist. 4867 Similar to ALREADYEXISTS. 4869 C: p RENAME this that 4870 S: p NO [NONEXISTENT] No such mailbox 4872 NOPERM 4874 The access control system (e.g., Access Control List (ACL), see 4875 [RFC4314] does not permit this user to carry out an operation, 4876 such as selecting or creating a mailbox. 4878 C: f select "/archive/projects/experiment-iv" 4879 S: f NO [NOPERM] Access denied 4881 OVERQUOTA 4883 The user would be over quota after the operation. (The user 4884 may or may not be over quota already.) 4886 Note that if the server sends OVERQUOTA but doesn't support the 4887 IMAP QUOTA extension defined by [RFC2087], then there is a 4888 quota, but the client cannot find out what the quota is. 4890 C: n1 uid copy 1:* oldmail 4891 S: n1 NO [OVERQUOTA] Sorry 4893 C: n2 uid copy 1:* oldmail 4894 S: n2 OK [OVERQUOTA] You are now over your soft quota 4896 PARSE 4898 The human-readable text represents an error in parsing the 4899 [RFC-5322] header or [MIME-IMB] headers of a message in the 4900 mailbox. 4902 PERMANENTFLAGS 4904 Followed by a parenthesized list of flags, indicates which of 4905 the known flags the client can change permanently. Any flags 4906 that are in the FLAGS untagged response, but not the 4907 PERMANENTFLAGS list, can not be set permanently. The 4908 PERMANENTFLAGS list can also include the special flag \*, which 4909 indicates that it is possible to create new keywords by 4910 attempting to store those keywords in the mailbox. If the 4911 client attempts to STORE a flag that is not in the 4912 PERMANENTFLAGS list, the server will either ignore the change 4913 or store the state change for the remainder of the current 4914 session only. 4916 There is no need for a server that included the special flag \* 4917 to return a new PERMANENTFLAGS response code when a new keyword 4918 was successfully set on a message upon client request. However 4919 if the server has a limit on the number of different keywords 4920 that can be stored in a mailbox and that limit is reached, the 4921 server MUST send a new PERMANENTFLAGS response code without the 4922 special flag \*. 4924 PRIVACYREQUIRED 4925 The operation is not permitted due to a lack of privacy. If 4926 Transport Layer Security (TLS) is not in use, the client could 4927 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4929 C: d login "fred" "foo" 4930 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4932 C: d select inbox 4933 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4935 READ-ONLY 4937 The mailbox is selected read-only, or its access while selected 4938 has changed from read-write to read-only. 4940 READ-WRITE 4942 The mailbox is selected read-write, or its access while 4943 selected has changed from read-only to read-write. 4945 SERVERBUG 4947 The server encountered a bug in itself or violated one of its 4948 own invariants. 4950 C: j select "/archive/projects/experiment-iv" 4951 S: j NO [SERVERBUG] This should not happen 4953 TRYCREATE 4955 An APPEND, COPY or MOVE attempt is failing because the target 4956 mailbox does not exist (as opposed to some other reason). This 4957 is a hint to the client that the operation can succeed if the 4958 mailbox is first created by the CREATE command. 4960 UIDNEXT 4962 Followed by a decimal number, indicates the next unique 4963 identifier value. Refer to Section 2.3.1.1 for more 4964 information. 4966 UIDNOTSTICKY 4968 The selected mailbox is supported by a mail store that does not 4969 support persistent UIDs; that is, UIDVALIDITY will be different 4970 each time the mailbox is selected. Consequently, APPEND or 4971 COPY to this mailbox will not return an APPENDUID or COPYUID 4972 response code. 4974 This response code is returned in an untagged NO response to 4975 the SELECT command. 4977 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4978 This facility exists to support legacy mail stores in which 4979 it is technically infeasible to support persistent UIDs. 4980 This should be avoided when designing new mail stores. 4982 UIDVALIDITY 4984 Followed by a decimal number, indicates the unique identifier 4985 validity value. Refer to Section 2.3.1.1 for more information. 4987 UNAVAILABLE 4989 Temporary failure because a subsystem is down. For example, an 4990 IMAP server that uses a Lightweight Directory Access Protocol 4991 (LDAP) or Radius server for authentication might use this 4992 response code when the LDAP/Radius server is down. 4994 C: a LOGIN "fred" "foo" 4995 S: a NO [UNAVAILABLE] User's backend down for maintenance 4997 UNKNOWN-CTE 4999 The server does not know how to decode the section's Content- 5000 Transfer-Encoding. 5002 Client implementations MUST ignore response codes that they do not 5003 recognize. 5005 7.1.1. OK Response 5007 Contents: OPTIONAL response code 5008 human-readable text 5010 The OK response indicates an information message from the server. 5011 When tagged, it indicates successful completion of the associated 5012 command. The human-readable text MAY be presented to the user as an 5013 information message. The untagged form indicates an information-only 5014 message; the nature of the information MAY be indicated by a response 5015 code. 5017 The untagged form is also used as one of three possible greetings at 5018 connection startup. It indicates that the connection is not yet 5019 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 5021 Example: S: * OK IMAP4rev2 server ready 5022 C: A001 LOGIN fred blurdybloop 5023 S: * OK [ALERT] System shutdown in 10 minutes 5024 S: A001 OK LOGIN Completed 5026 7.1.2. NO Response 5028 Contents: OPTIONAL response code 5029 human-readable text 5031 The NO response indicates an operational error message from the 5032 server. When tagged, it indicates unsuccessful completion of the 5033 associated command. The untagged form indicates a warning; the 5034 command can still complete successfully. The human-readable text 5035 describes the condition. 5037 Example: C: A222 COPY 1:2 owatagusiam 5038 S: * NO Disk is 98% full, please delete unnecessary data 5039 S: A222 OK COPY completed 5040 C: A223 COPY 3:200 blurdybloop 5041 S: * NO Disk is 98% full, please delete unnecessary data 5042 S: * NO Disk is 99% full, please delete unnecessary data 5043 S: A223 NO COPY failed: disk is full 5045 7.1.3. BAD Response 5047 Contents: OPTIONAL response code 5048 human-readable text 5050 The BAD response indicates an error message from the server. When 5051 tagged, it reports a protocol-level error in the client's command; 5052 the tag indicates the command that caused the error. The untagged 5053 form indicates a protocol-level error for which the associated 5054 command can not be determined; it can also indicate an internal 5055 server failure. The human-readable text describes the condition. 5057 Example: C: ...very long command line... 5058 S: * BAD Command line too long 5059 C: ...empty line... 5060 S: * BAD Empty command line 5061 C: A443 EXPUNGE 5062 S: * BAD Disk crash, attempting salvage to a new disk! 5063 S: * OK Salvage successful, no data lost 5064 S: A443 OK Expunge completed 5066 7.1.4. PREAUTH Response 5068 Contents: OPTIONAL response code 5069 human-readable text 5071 The PREAUTH response is always untagged, and is one of three possible 5072 greetings at connection startup. It indicates that the connection 5073 has already been authenticated by external means; thus no LOGIN/ 5074 AUTHENTICATE command is needed. 5076 Because PREAUTH moves the connection directly to the authenticated 5077 state, it effectively prevents the client from using the STARTTLS 5078 command Section 6.2.1. For this reason PREAUTH response SHOULD only 5079 be returned by servers on connections that are protected by TLS (such 5080 as on IMAPS port [RFC8314]) or protected through other means such as 5081 IPSec. Clients that require mandatory TLS MUST close the connection 5082 after receiving PREAUTH response on a non protected port. 5084 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 5086 7.1.5. BYE Response 5088 Contents: OPTIONAL response code 5089 human-readable text 5091 The BYE response is always untagged, and indicates that the server is 5092 about to close the connection. The human-readable text MAY be 5093 displayed to the user in a status report by the client. The BYE 5094 response is sent under one of four conditions: 5096 1. as part of a normal logout sequence. The server will close the 5097 connection after sending the tagged OK response to the LOGOUT 5098 command. 5100 2. as a panic shutdown announcement. The server closes the 5101 connection immediately. 5103 3. as an announcement of an inactivity autologout. The server 5104 closes the connection immediately. 5106 4. as one of three possible greetings at connection startup, 5107 indicating that the server is not willing to accept a connection 5108 from this client. The server closes the connection immediately. 5110 The difference between a BYE that occurs as part of a normal LOGOUT 5111 sequence (the first case) and a BYE that occurs because of a failure 5112 (the other three cases) is that the connection closes immediately in 5113 the failure case. In all cases the client SHOULD continue to read 5114 response data from the server until the connection is closed; this 5115 will ensure that any pending untagged or completion responses are 5116 read and processed. 5118 Example: S: * BYE Autologout; idle for too long 5120 7.2. Server Responses - Server Status 5122 These responses are always untagged. This is how server and mailbox 5123 status data are transmitted from the server to the client. 5125 7.2.1. ENABLED Response 5127 Contents: capability listing 5129 The ENABLED response occurs as a result of an ENABLE command. The 5130 capability listing contains a space-separated listing of capability 5131 names that the server supports and that were successfully enabled. 5132 The ENABLED response may contain no capabilities, which means that no 5133 extensions listed by the client were successfully enabled. 5135 Example: S: * ENABLED CONDSTORE QRESYNC 5137 7.2.2. CAPABILITY Response 5139 Contents: capability listing 5141 The CAPABILITY response occurs as a result of a CAPABILITY command. 5142 The capability listing contains a space-separated listing of 5143 capability names that the server supports. The capability listing 5144 MUST include the atom "IMAP4rev2", but note that it doesn't have to 5145 be the first capability listed. The order of capability names has no 5146 significance. 5148 In addition, client and server implementations MUST implement the 5149 "STARTTLS", "LOGINDISABLED", and "AUTH=PLAIN" (described in [PLAIN]) 5150 capabilities. See the Security Considerations (Section 11) for 5151 important information related to these capabilities. 5153 A capability name which begins with "AUTH=" indicates that the server 5154 supports that particular authentication mechanism [SASL]. 5156 The LOGINDISABLED capability indicates that the LOGIN command is 5157 disabled, and that the server will respond with a tagged NO response 5158 to any attempt to use the LOGIN command even if the user name and 5159 password are valid. An IMAP client MUST NOT issue the LOGIN command 5160 if the server advertises the LOGINDISABLED capability. 5162 Other capability names indicate that the server supports an 5163 extension, revision, or amendment to the IMAP4rev2 protocol. Server 5164 responses MUST conform to this document until the client issues a 5165 command that uses the associated capability. 5167 Capability names SHOULD be registered with IANA using RFC Required 5168 policy. A server SHOULD NOT offer unregistered capability names. 5170 Client implementations SHOULD NOT require any capability name other 5171 than "IMAP4rev2", "STARTTLS", "LOGINDISABLED". Client 5172 implementations MUST ignore any unknown capability names. 5174 A server MAY send capabilities automatically, by using the CAPABILITY 5175 response code in the initial PREAUTH or OK responses, and by sending 5176 an updated CAPABILITY response code in the tagged OK response as part 5177 of a successful authentication. It is unnecessary for a client to 5178 send a separate CAPABILITY command if it recognizes these automatic 5179 capabilities. 5181 The list of capabilities returned by a server MAY change during the 5182 connection. In particular, it is quite common for the server to 5183 change list of capabilities after successful TLS negotiation 5184 (STARTTLS command) and/or after successful authentication 5185 (AUTHENTICATE or LOGIN commands). 5187 Example: S: * CAPABILITY STARTTLS AUTH=GSSAPI IMAP4rev2 LOGINDISABLED 5188 XPIG-LATIN 5190 Note that in the above example XPIG-LATIN is a fictitious capability 5191 name. 5193 7.3. Server Responses - Mailbox Status 5195 These responses are always untagged. This is how server and mailbox 5196 status data are transmitted from the server to the client. Many of 5197 these responses typically result from a command with the same name. 5199 7.3.1. LIST Response 5201 Contents: name attributes 5202 hierarchy delimiter 5203 name 5204 OPTIONAL extension data 5206 The LIST response occurs as a result of a LIST command. It returns a 5207 single name that matches the LIST specification. There can be 5208 multiple LIST responses for a single LIST command. 5210 The following base mailbox name attributes are defined: 5212 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5213 name does not refer to an existing mailbox. Note that this 5214 attribute is not meaningful by itself, as mailbox names that match 5215 the canonical LIST pattern but don't exist must not be returned 5216 unless one of the two conditions listed below is also satisfied: 5218 1. The mailbox name also satisfies the selection criteria (for 5219 example, it is subscribed and the "SUBSCRIBED" selection 5220 option has been specified). 5222 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5223 at least one descendant mailbox name that does not match the 5224 LIST pattern and does match the selection criteria. 5226 In practice, this means that the "\NonExistent" attribute is 5227 usually returned with one or more of "\Subscribed", "\Remote", 5228 "\HasChildren", or the CHILDINFO extended data item. 5230 The "\NonExistent" attribute implies "\NoSelect". 5232 \Noinferiors It is not possible for any child levels of hierarchy to 5233 exist under this name; no child levels exist now and none can be 5234 created in the future. 5236 \Noselect It is not possible to use this name as a selectable 5237 mailbox. 5239 \HasChildren The presence of this attribute indicates that the 5240 mailbox has child mailboxes. A server SHOULD NOT set this 5241 attribute if there are child mailboxes and the user does not have 5242 permission to access any of them. In this case, \HasNoChildren 5243 SHOULD be used. In many cases, however, a server may not be able 5244 to efficiently compute whether a user has access to any child 5245 mailbox. Note that even though the \HasChildren attribute for a 5246 mailbox must be correct at the time of processing of the mailbox, 5247 a client must be prepared to deal with a situation when a mailbox 5248 is marked with the \HasChildren attribute, but no child mailbox 5249 appears in the response to the LIST command. This might happen, 5250 for example, due to children mailboxes being deleted or made 5251 inaccessible to the user (using access control) by another client 5252 before the server is able to list them. 5254 \HasNoChildren The presence of this attribute indicates that the 5255 mailbox has NO child mailboxes that are accessible to the 5256 currently authenticated user. 5258 \Marked The mailbox has been marked "interesting" by the server; the 5259 mailbox probably contains messages that have been added since the 5260 last time the mailbox was selected. 5262 \Unmarked The mailbox does not contain any additional messages since 5263 the last time the mailbox was selected. 5265 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5266 command. 5268 \Remote The mailbox is a remote mailbox. 5270 It is an error for the server to return both a \HasChildren and a 5271 \HasNoChildren attribute in the same LIST response. A client that 5272 encounters a LIST response with both \HasChildren and \HasNoChildren 5273 attributes present should act as if both are absent in the LIST 5274 response. 5276 Note: the \HasNoChildren attribute should not be confused with the 5277 \NoInferiors attribute, which indicates that no child mailboxes 5278 exist now and none can be created in the future. 5280 If it is not feasible for the server to determine whether or not the 5281 mailbox is "interesting", the server SHOULD NOT send either \Marked 5282 or \Unmarked. The server MUST NOT send more than one of \Marked, 5283 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5284 these. 5286 In addition to the base mailbox name attributes defined above, an 5287 IMAP server MAY also include any or all of the following attributes 5288 that denote "role" (or "special-use") of a mailbox. These attributes 5289 are included along with base attributes defined above. A given 5290 mailbox may have none, one, or more than one of these attributes. In 5291 some cases, a special use is advice to a client about what to put in 5292 that mailbox. In other cases, it's advice to a client about what to 5293 expect to find there. 5295 \All This mailbox presents all messages in the user's message store. 5296 Implementations MAY omit some messages, such as, perhaps, those in 5297 \Trash and \Junk. When this special use is supported, it is 5298 almost certain to represent a virtual mailbox. 5300 \Archive This mailbox is used to archive messages. The meaning of 5301 an "archival" mailbox is server-dependent; typically, it will be 5302 used to get messages out of the inbox, or otherwise keep them out 5303 of the user's way, while still making them accessible. 5305 \Drafts This mailbox is used to hold draft messages -- typically, 5306 messages that are being composed but have not yet been sent. In 5307 some server implementations, this might be a virtual mailbox, 5308 containing messages from other mailboxes that are marked with the 5309 "\Draft" message flag. Alternatively, this might just be advice 5310 that a client put drafts here. 5312 \Flagged This mailbox presents all messages marked in some way as 5313 "important". When this special use is supported, it is likely to 5314 represent a virtual mailbox collecting messages (from other 5315 mailboxes) that are marked with the "\Flagged" message flag. 5317 \Junk This mailbox is where messages deemed to be junk mail are 5318 held. Some server implementations might put messages here 5319 automatically. Alternatively, this might just be advice to a 5320 client-side spam filter. 5322 \Sent This mailbox is used to hold copies of messages that have been 5323 sent. Some server implementations might put messages here 5324 automatically. Alternatively, this might just be advice that a 5325 client save sent messages here. 5327 \Trash This mailbox is used to hold messages that have been deleted 5328 or marked for deletion. In some server implementations, this 5329 might be a virtual mailbox, containing messages from other 5330 mailboxes that are marked with the "\Deleted" message flag. 5331 Alternatively, this might just be advice that a client that 5332 chooses not to use the IMAP "\Deleted" model should use this as 5333 its trash location. In server implementations that strictly 5334 expect the IMAP "\Deleted" model, this special use is likely not 5335 to be supported. 5337 All of special-use attributes are OPTIONAL, and any given server or 5338 message store may support any combination of the attributes, or none 5339 at all. In most cases, there will likely be at most one mailbox with 5340 a given attribute for a given user, but in some server or message 5341 store implementations it might be possible for multiple mailboxes to 5342 have the same special-use attribute. 5344 Special-use attributes are likely to be user-specific. User Adam 5345 might share his \Sent mailbox with user Barb, but that mailbox is 5346 unlikely to also serve as Barb's \Sent mailbox. 5348 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5349 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5351 The hierarchy delimiter is a character used to delimit levels of 5352 hierarchy in a mailbox name. A client can use it to create child 5353 mailboxes, and to search higher or lower levels of naming hierarchy. 5354 All children of a top-level hierarchy node MUST use the same 5355 separator character. A NIL hierarchy delimiter means that no 5356 hierarchy exists; the name is a "flat" name. 5358 The name represents an unambiguous left-to-right hierarchy, and MUST 5359 be valid for use as a reference in LIST command. Unless \Noselect or 5360 \NonExistent is indicated, the name MUST also be valid as an argument 5361 for commands, such as SELECT, that accept mailbox names. 5363 The name might be followed by an OPTIONAL series of extended fields, 5364 a parenthesized list of tagged data (also referred to as "extended 5365 data item"). The first element of an extended field is a string, 5366 which identifies the type of data. [RFC5258] specified requirements 5367 on string registration (which are called "tags" there; such tags are 5368 not to be confused with IMAP command tags), in particular it said 5369 that "Tags MUST be registered with IANA". This document doesn't 5370 change that. See Section 9.5 of [RFC5258] for the registration 5371 template. The server MAY return data in the extended fields that was 5372 not directly solicited by the client in the corresponding LIST 5373 command. For example, the client can enable extra extended fields by 5374 using another IMAP extension that make use of the extended LIST 5375 responses. The client MUST ignore all extended fields it doesn't 5376 recognize. 5378 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5380 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5381 ("color" "red")) Sample "text") 5382 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5383 Sample ("text" "more text")) 5385 7.3.2. NAMESPACE Response 5387 Contents: the prefix and hierarchy delimiter to the server's 5388 Personal Namespace(s), Other Users' Namespace(s), and 5389 Shared Namespace(s) 5391 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5392 contains the prefix and hierarchy delimiter to the server's Personal 5393 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5394 the server wishes to expose. The response will contain a NIL for any 5395 namespace class that is not available. Namespace-Response-Extensions 5396 ABNF non terminal is defined for extensibility and MAY be included in 5397 the response. 5399 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5401 7.3.3. STATUS Response 5403 Contents: name 5404 status parenthesized list 5406 The STATUS response occurs as a result of an STATUS command. It 5407 returns the mailbox name that matches the STATUS specification and 5408 the requested mailbox status information. 5410 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5412 7.3.4. ESEARCH Response 5414 Contents: one or more search-return-data pairs 5416 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5417 command. 5419 The ESEARCH response starts with an optional search correlator. If 5420 it is missing, then the response was not caused by a particular IMAP 5421 command, whereas if it is present, it contains the tag of the command 5422 that caused the response to be returned. 5424 The search correlator is followed by an optional UID indicator. If 5425 this indicator is present, all data in the ESEARCH response refers to 5426 UIDs, otherwise all returned data refers to message numbers. 5428 The rest of the ESEARCH response contains one or more search data 5429 pairs. Each pair starts with unique return item name, followed by a 5430 space and the corresponding data. Search data pairs may be returned 5431 in any order. Unless specified otherwise by an extension, any return 5432 item name SHOULD appear only once in an ESEARCH response. 5434 [[TBD: describe the most common search data pairs returned.]] 5436 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5438 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5440 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5442 7.3.5. FLAGS Response 5444 Contents: flag parenthesized list 5446 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5447 The flag parenthesized list identifies the flags (at a minimum, the 5448 system-defined flags) that are applicable for this mailbox. Flags 5449 other than the system flags can also exist, depending on server 5450 implementation. 5452 The update from the FLAGS response MUST be remembered by the client. 5454 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5456 7.4. Server Responses - Mailbox Size 5458 These responses are always untagged. This is how changes in the size 5459 of the mailbox are transmitted from the server to the client. 5460 Immediately following the "*" token is a number that represents a 5461 message count. 5463 7.4.1. EXISTS Response 5465 Contents: none 5467 The EXISTS response reports the number of messages in the mailbox. 5468 This response occurs as a result of a SELECT or EXAMINE command, and 5469 if the size of the mailbox changes (e.g., new messages). 5471 The update from the EXISTS response MUST be remembered by the client. 5473 Example: S: * 23 EXISTS 5475 7.5. Server Responses - Message Status 5477 These responses are always untagged. This is how message data are 5478 transmitted from the server to the client, often as a result of a 5479 command with the same name. Immediately following the "*" token is a 5480 number that represents a message sequence number. 5482 7.5.1. EXPUNGE Response 5484 Contents: none 5486 The EXPUNGE response reports that the specified message sequence 5487 number has been permanently removed from the mailbox. The message 5488 sequence number for each successive message in the mailbox is 5489 immediately decremented by 1, and this decrement is reflected in 5490 message sequence numbers in subsequent responses (including other 5491 untagged EXPUNGE responses). 5493 The EXPUNGE response also decrements the number of messages in the 5494 mailbox; it is not necessary to send an EXISTS response with the new 5495 value. 5497 As a result of the immediate decrement rule, message sequence numbers 5498 that appear in a set of successive EXPUNGE responses depend upon 5499 whether the messages are removed starting from lower numbers to 5500 higher numbers, or from higher numbers to lower numbers. For 5501 example, if the last 5 messages in a 9-message mailbox are expunged, 5502 a "lower to higher" server will send five untagged EXPUNGE responses 5503 for message sequence number 5, whereas a "higher to lower server" 5504 will send successive untagged EXPUNGE responses for message sequence 5505 numbers 9, 8, 7, 6, and 5. 5507 An EXPUNGE response MUST NOT be sent when no command is in progress, 5508 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5509 is necessary to prevent a loss of synchronization of message sequence 5510 numbers between client and server. A command is not "in progress" 5511 until the complete command has been received; in particular, a 5512 command is not "in progress" during the negotiation of command 5513 continuation. 5515 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5516 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5517 during a UID command. 5519 The update from the EXPUNGE response MUST be remembered by the 5520 client. 5522 Example: S: * 44 EXPUNGE 5524 7.5.2. FETCH Response 5526 Contents: message data 5528 The FETCH response returns data about a message to the client. The 5529 data are pairs of data item names and their values in parentheses. 5530 This response occurs as the result of a FETCH or STORE command, as 5531 well as by unilateral server decision (e.g., flag updates). 5533 The current data items are: 5535 BINARY[]<> 5537 An or expressing the content of the 5538 specified section after removing any Content-Transfer-Encoding- 5539 related encoding. If is present it refers to the 5540 offset within the DECODED section data. 5542 If the domain of the decoded data is "8bit" and the data does 5543 not contain the NUL octet, the server SHOULD return the data in 5544 a instead of a ; this allows the client to 5545 determine if the "8bit" data contains the NUL octet without 5546 having to explicitly scan the data stream for for NULs. 5548 Messaging clients and servers have been notoriously lax in 5549 their adherence to the Internet CRLF convention for terminating 5550 lines of textual data (text/* media types) in Internet 5551 protocols. When sending data in BINARY[...] FETCH data item, 5552 servers MUST ensure that textual line-oriented sections are 5553 always transmitted using the IMAP4 CRLF line termination 5554 syntax, regardless of the underlying storage representation of 5555 the data on the server. 5557 If the server does not know how to decode the section's 5558 Content-Transfer-Encoding, it MUST fail the request and issue a 5559 "NO" response that contains the "UNKNOWN-CTE" response code. 5561 BINARY.SIZE[] 5563 The size of the section after removing any Content-Transfer- 5564 Encoding-related encoding. The value returned MUST match the 5565 size of the or that will be returned by 5566 the corresponding FETCH BINARY request. 5568 If the server does not know how to decode the section's 5569 Content-Transfer-Encoding, it MUST fail the request and issue a 5570 "NO" response that contains the "UNKNOWN-CTE" response code. 5572 BODY A form of BODYSTRUCTURE without extension data. 5574 BODY[
]<> 5576 A string expressing the body contents of the specified section. 5577 The string SHOULD be interpreted by the client according to the 5578 content transfer encoding, body type, and subtype. 5580 If the origin octet is specified, this string is a substring of 5581 the entire body contents, starting at that origin octet. This 5582 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5583 truncated. 5585 Note: The origin octet facility MUST NOT be used by a server 5586 in a FETCH response unless the client specifically requested 5587 it by means of a FETCH of a BODY[
]<> data 5588 item. 5590 8-bit textual data is permitted if a [CHARSET] identifier is 5591 part of the body parameter parenthesized list for this section. 5592 Note that headers (part specifiers HEADER or MIME, or the 5593 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5594 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5595 line between the header and the body is not affected by header 5596 line subsetting; the blank line is always included as part of 5597 header data, except in the case of a message which has no body 5598 and no blank line. 5600 Non-textual data such as binary data MUST be transfer encoded 5601 into a textual form, such as BASE64, prior to being sent to the 5602 client. To derive the original binary data, the client MUST 5603 decode the transfer encoded string. 5605 BODYSTRUCTURE 5607 A parenthesized list that describes the [MIME-IMB] body 5608 structure of a message. This is computed by the server by 5609 parsing the [MIME-IMB] header fields, defaulting various fields 5610 as necessary. 5612 For example, a simple text message of 48 lines and 2279 octets 5613 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5614 ASCII") NIL NIL "7BIT" 2279 48) 5616 Multiple parts are indicated by parenthesis nesting. Instead 5617 of a body type as the first element of the parenthesized list, 5618 there is a sequence of one or more nested body structures. The 5619 second element of the parenthesized list is the multipart 5620 subtype (mixed, digest, parallel, alternative, etc.). 5622 For example, a two part message consisting of a text and a 5623 BASE64-encoded text attachment can have a body structure of: 5624 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5625 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5626 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5627 "BASE64" 4554 73) "MIXED") 5629 Extension data follows the multipart subtype. Extension data 5630 is never returned with the BODY fetch, but can be returned with 5631 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5632 the defined order. The extension data of a multipart body part 5633 are in the following order: 5635 body parameter parenthesized list A parenthesized list of 5636 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5637 "bar" is the value of "foo", and "rag" is the value of 5638 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5639 parameter value continuations and parameter value character 5640 sets as described in [RFC2231], for example, if the message 5641 contains parameters "baz*0", "baz*1" and "baz*2", the server 5642 should RFC2231-decode them, concatenate and return the 5643 resulting value as a parameter "baz". Similarly, if the 5644 message contains parameters "foo*0*" and "foo*1*", the 5645 server should RFC2231-decode them, convert to UTF-8, 5646 concatenate and return the resulting value as a parameter 5647 "foo*". 5649 body disposition A parenthesized list, consisting of a 5650 disposition type string, followed by a parenthesized list of 5651 disposition attribute/value pairs as defined in 5652 [DISPOSITION]. Servers SHOULD decode parameter value 5653 continuations as described in [RFC2231]. 5655 body language A string or parenthesized list giving the body 5656 language value as defined in [LANGUAGE-TAGS]. 5658 body location A string giving the body content URI as defined 5659 in [LOCATION]. 5661 Any following extension data are not yet defined in this 5662 version of the protocol. Such extension data can consist of 5663 zero or more NILs, strings, numbers, or potentially nested 5664 parenthesized lists of such data. Client implementations that 5665 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5666 extension data. Server implementations MUST NOT send such 5667 extension data until it has been defined by a revision of this 5668 protocol. 5670 The basic fields of a non-multipart body part are in the 5671 following order: 5673 body type A string giving the content media type name as 5674 defined in [MIME-IMB]. 5676 body subtype A string giving the content subtype name as 5677 defined in [MIME-IMB]. 5679 body parameter parenthesized list A parenthesized list of 5680 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5681 "bar" is the value of "foo" and "rag" is the value of "baz"] 5682 as defined in [MIME-IMB]. 5684 body id A string giving the Content-ID header field value as 5685 defined in Section 7 of [MIME-IMB]. 5687 body description A string giving the Content-Description 5688 header field value as defined in Section 8 of [MIME-IMB]. 5690 body encoding A string giving the content transfer encoding as 5691 defined in Section 6 of [MIME-IMB]. 5693 body size A number giving the size of the body in octets. 5694 Note that this size is the size in its transfer encoding and 5695 not the resulting size after any decoding. 5697 A body type of type MESSAGE and subtype RFC822 contains, 5698 immediately after the basic fields, the envelope structure, 5699 body structure, and size in text lines of the encapsulated 5700 message. 5702 A body type of type TEXT contains, immediately after the basic 5703 fields, the size of the body in text lines. Note that this 5704 size is the size in its content transfer encoding and not the 5705 resulting size after any decoding. 5707 Extension data follows the basic fields and the type-specific 5708 fields listed above. Extension data is never returned with the 5709 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5710 Extension data, if present, MUST be in the defined order. 5712 The extension data of a non-multipart body part are in the 5713 following order: 5715 body MD5 A string giving the body MD5 value as defined in 5716 [MD5]. 5718 body disposition A parenthesized list with the same content 5719 and function as the body disposition for a multipart body 5720 part. 5722 body language A string or parenthesized list giving the body 5723 language value as defined in [LANGUAGE-TAGS]. 5725 body location A string giving the body content URI as defined 5726 in [LOCATION]. 5728 Any following extension data are not yet defined in this 5729 version of the protocol, and would be as described above under 5730 multipart extension data. 5732 ENVELOPE 5734 A parenthesized list that describes the envelope structure of a 5735 message. This is computed by the server by parsing the 5736 [RFC-5322] header into the component parts, defaulting various 5737 fields as necessary. 5739 The fields of the envelope structure are in the following 5740 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5741 reply-to, and message-id. The date, subject, in-reply-to, and 5742 message-id fields are strings. The from, sender, reply-to, to, 5743 cc, and bcc fields are parenthesized lists of address 5744 structures. 5746 An address structure is a parenthesized list that describes an 5747 electronic mail address. The fields of an address structure 5748 are in the following order: personal name, [SMTP] at-domain- 5749 list (source route, obs-route), mailbox name, and host name. 5751 [RFC-5322] group syntax is indicated by a special form of 5752 address structure in which the host name field is NIL. If the 5753 mailbox name field is also NIL, this is an end of group marker 5754 (semi-colon in RFC 822 syntax). If the mailbox name field is 5755 non-NIL, this is a start of group marker, and the mailbox name 5756 field holds the group name phrase. 5758 If the Date, Subject, In-Reply-To, and Message-ID header fields 5759 are absent in the [RFC-5322] header, the corresponding member 5760 of the envelope is NIL; if these header fields are present but 5761 empty the corresponding member of the envelope is the empty 5762 string. 5764 Note: some servers may return a NIL envelope member in the 5765 "present but empty" case. Clients SHOULD treat NIL and 5766 empty string as identical. 5768 Note: [RFC-5322] requires that all messages have a valid 5769 Date header field. Therefore, for a well-formed message the 5770 date member in the envelope can not be NIL or the empty 5771 string. However it can be NIL for a malformed or a draft 5772 message. 5774 Note: [RFC-5322] requires that the In-Reply-To and Message- 5775 ID header fields, if present, have non-empty content. 5776 Therefore, for a well-formed message the in-reply-to and 5777 message-id members in the envelope can not be the empty 5778 string. However they can still be the empty string for a 5779 malformed message. 5781 If the From, To, Cc, and Bcc header fields are absent in the 5782 [RFC-5322] header, or are present but empty, the corresponding 5783 member of the envelope is NIL. 5785 If the Sender or Reply-To header fields are absent in the 5786 [RFC-5322] header, or are present but empty, the server sets 5787 the corresponding member of the envelope to be the same value 5788 as the from member (the client is not expected to know to do 5789 this). 5791 Note: [RFC-5322] requires that all messages have a valid 5792 From header field. Therefore, for a well-formed message the 5793 from, sender, and reply-to members in the envelope can not 5794 be NIL. However they can be NIL for a malformed or a draft 5795 message. 5797 FLAGS A parenthesized list of flags that are set for this message. 5799 INTERNALDATE A string representing the internal date of the message. 5801 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5803 UID A number expressing the unique identifier of the message. 5805 If the server chooses to send unsolicited FETCH responses, they MUST 5806 include UID FETCH item. Note that this is a new requirement when 5807 compared to RFC 3501. 5809 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5811 7.6. Server Responses - Command Continuation Request 5813 The command continuation request response is indicated by a "+" token 5814 instead of a tag. This form of response indicates that the server is 5815 ready to accept the continuation of a command from the client. The 5816 remainder of this response is a line of text. 5818 This response is used in the AUTHENTICATE command to transmit server 5819 data to the client, and request additional client data. This 5820 response is also used if an argument to any command is a 5821 synchronizing literal. 5823 The client is not permitted to send the octets of the synchronizing 5824 literal unless the server indicates that it is expected. This 5825 permits the server to process commands and reject errors on a line- 5826 by-line basis. The remainder of the command, including the CRLF that 5827 terminates a command, follows the octets of the literal. If there 5828 are any additional command arguments, the literal octets are followed 5829 by a space and those arguments. 5831 Example: C: A001 LOGIN {11} 5832 S: + Ready for additional command text 5833 C: FRED FOOBAR {7} 5834 S: + Ready for additional command text 5835 C: fat man 5836 S: A001 OK LOGIN completed 5837 C: A044 BLURDYBLOOP {102856} 5838 S: A044 BAD No such command as "BLURDYBLOOP" 5840 8. Sample IMAP4rev2 connection 5842 The following is a transcript of an IMAP4rev2 connection. A long 5843 line in this sample is broken for editorial clarity. 5845 S: * OK IMAP4rev2 Service Ready 5846 C: a001 login mrc secret 5847 S: a001 OK LOGIN completed 5848 C: a002 select inbox 5849 S: * 18 EXISTS 5850 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5851 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5852 S: * LIST () "/" INBOX ("OLDNAME" ("inbox")) 5853 S: a002 OK [READ-WRITE] SELECT completed 5854 C: a003 fetch 12 full 5855 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5856 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5857 "IMAP4rev2 WG mtg summary and minutes" 5858 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5859 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5860 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5861 ((NIL NIL "imap" "cac.washington.edu")) 5862 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5863 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5864 "") 5865 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5866 92)) 5867 S: a003 OK FETCH completed 5868 C: a004 fetch 12 body[header] 5869 S: * 12 FETCH (BODY[HEADER] {342} 5870 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5871 S: From: Terry Gray 5872 S: Subject: IMAP4rev2 WG mtg summary and minutes 5873 S: To: imap@cac.washington.edu 5874 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5875 S: Message-Id: 5876 S: MIME-Version: 1.0 5877 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5878 S: 5879 S: ) 5880 S: a004 OK FETCH completed 5881 C: a005 store 12 +flags \deleted 5882 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5883 S: a005 OK +FLAGS completed 5884 C: a006 logout 5885 S: * BYE IMAP4rev2 server terminating connection 5886 S: a006 OK LOGOUT completed 5888 9. Formal Syntax 5890 The following syntax specification uses the Augmented Backus-Naur 5891 Form (ABNF) notation as specified in [ABNF]. 5893 In the case of alternative or optional rules in which a later rule 5894 overlaps an earlier rule, the rule which is listed earlier MUST take 5895 priority. For example, "\Seen" when parsed as a flag is the \Seen 5896 flag name and not a flag-extension, even though "\Seen" can be parsed 5897 as a flag-extension. Some, but not all, instances of this rule are 5898 noted below. 5900 Note: [ABNF] rules MUST be followed strictly; in particular: 5902 (1) Except as noted otherwise, all alphabetic characters are case- 5903 insensitive. The use of upper or lower case characters to define 5904 token strings is for editorial clarity only. Implementations MUST 5905 accept these strings in a case-insensitive fashion. 5907 (2) In all cases, SP refers to exactly one space. It is NOT 5908 permitted to substitute TAB, insert additional spaces, or 5909 otherwise treat SP as being equivalent to LWSP. 5911 (3) The ASCII NUL character, %x00, MUST NOT be used anywhere, with 5912 the exception of the OCTET production. 5914 SP = 5915 CTL = 5916 CRLF = 5917 ALPHA = 5918 DIGIT = 5919 DQUOTE = 5920 OCTET = 5922 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5923 addr-host ")" 5925 addr-adl = nstring 5926 ; Holds route from [RFC-5322] obs-route if 5927 ; non-NIL 5929 addr-host = nstring 5930 ; NIL indicates [RFC-5322] group syntax. 5931 ; Otherwise, holds [RFC-5322] domain name 5933 addr-mailbox = nstring 5934 ; NIL indicates end of [RFC-5322] group; if 5935 ; non-NIL and addr-host is NIL, holds 5936 ; [RFC-5322] group name. 5937 ; Otherwise, holds [RFC-5322] local-part 5938 ; after removing [RFC-5322] quoting 5940 addr-name = nstring 5941 ; If non-NIL, holds phrase from [RFC-5322] 5942 ; mailbox after removing [RFC-5322] quoting 5944 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5945 literal 5947 append-uid = uniqueid 5949 astring = 1*ASTRING-CHAR / string 5951 ASTRING-CHAR = ATOM-CHAR / resp-specials 5953 atom = 1*ATOM-CHAR 5955 ATOM-CHAR = 5957 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5958 quoted-specials / resp-specials 5960 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5961 *(CRLF base64) 5963 auth-type = atom 5964 ; Defined by [SASL] 5966 base64 = *(4base64-char) [base64-terminal] 5968 base64-char = ALPHA / DIGIT / "+" / "/" 5969 ; Case-sensitive 5971 base64-terminal = (2base64-char "==") / (3base64-char "=") 5973 body = "(" (body-type-1part / body-type-mpart) ")" 5975 body-extension = nstring / number / number64 / 5976 "(" body-extension *(SP body-extension) ")" 5977 ; Future expansion. Client implementations 5978 ; MUST accept body-extension fields. Server 5979 ; implementations MUST NOT generate 5980 ; body-extension fields except as defined by 5981 ; future standard or standards-track 5982 ; revisions of this specification. 5984 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5985 [SP body-fld-loc *(SP body-extension)]]] 5986 ; MUST NOT be returned on non-extensible 5987 ; "BODY" fetch 5989 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5990 [SP body-fld-loc *(SP body-extension)]]] 5991 ; MUST NOT be returned on non-extensible 5992 ; "BODY" fetch 5994 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5995 body-fld-enc SP body-fld-octets 5997 body-fld-desc = nstring 5999 body-fld-dsp = "(" string SP body-fld-param ")" / nil 6001 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 6002 "QUOTED-PRINTABLE") DQUOTE) / string 6003 ; Content-Transfer-Encoding header field value. 6004 ; Defaults to "7BIT" (as per RFC 2045) 6005 ; if not present in the body part. 6007 body-fld-id = nstring 6009 body-fld-lang = nstring / "(" string *(SP string) ")" 6011 body-fld-loc = nstring 6013 body-fld-lines = number64 6015 body-fld-md5 = nstring 6017 body-fld-octets = number 6019 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 6021 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 6022 [SP body-ext-1part] 6024 body-type-basic = media-basic SP body-fields 6025 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 6027 body-type-mpart = 1*body SP media-subtype 6028 [SP body-ext-mpart] 6029 ; MULTIPART body part 6031 body-type-msg = media-message SP body-fields SP envelope 6032 SP body SP body-fld-lines 6034 body-type-text = media-text SP body-fields SP body-fld-lines 6036 capability = ("AUTH=" auth-type) / atom 6037 ; New capabilities MUST begin with "X" or be 6038 ; registered with IANA in 6039 ; a standards-track, an experimental 6040 ; or an informational RFC. 6042 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 6043 *(SP capability) 6044 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 6045 ; and LOGINDISABLED capabilities. 6046 ; Servers which offer RFC 1730 compatibility MUST 6047 ; list "IMAP4" as the first capability. 6048 ; Servers which offer RFC 3501 compatibility MUST 6049 ; list "IMAP4rev1" as one of capabilities. 6051 CHAR = 6053 CHAR8 = %x01-ff 6054 ; any OCTET except NUL, %x00 6056 charset = atom / quoted 6058 childinfo-extended-item = "CHILDINFO" SP "(" 6059 list-select-base-opt-quoted 6060 *(SP list-select-base-opt-quoted) ")" 6061 ; Extended data item (mbox-list-extended-item) 6062 ; returned when the RECURSIVEMATCH 6063 ; selection option is specified. 6064 ; Note 1: the CHILDINFO extended data item tag can be 6065 ; returned with and without surrounding quotes, as per 6066 ; mbox-list-extended-item-tag production. 6067 ; Note 2: The selection options are always returned 6068 ; quoted, unlike their specification in 6069 ; the extended LIST command. 6071 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 6072 ; attributes for CHILDREN return option, at most one 6073 ; possible per LIST response 6075 command = tag SP (command-any / command-auth / command-nonauth / 6076 command-select) CRLF 6077 ; Modal based on state 6079 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / x-command 6080 ; Valid in all states 6082 command-auth = append / create / delete / enable / examine / list / 6083 Namespace-Command / 6084 rename / select / status / subscribe / unsubscribe / 6085 idle 6086 ; Valid only in Authenticated or Selected state 6088 command-nonauth = login / authenticate / "STARTTLS" 6089 ; Valid only when in Not Authenticated state 6091 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 6092 move / fetch / store / search / uid 6093 ; Valid only when in Selected state 6095 continue-req = "+" SP (resp-text / base64) CRLF 6097 copy = "COPY" SP sequence-set SP mailbox 6099 create = "CREATE" SP mailbox 6100 ; Use of INBOX gives a NO error 6102 date = date-text / DQUOTE date-text DQUOTE 6104 date-day = 1*2DIGIT 6105 ; Day of month 6107 date-day-fixed = (SP DIGIT) / 2DIGIT 6108 ; Fixed-format version of date-day 6110 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 6111 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 6113 date-text = date-day "-" date-month "-" date-year 6115 date-year = 4DIGIT 6117 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 6118 SP time SP zone DQUOTE 6120 delete = "DELETE" SP mailbox 6121 ; Use of INBOX gives a NO error 6123 digit-nz = %x31-39 6124 ; 1-9 6126 eitem-standard-tag = atom 6127 ; a tag for LIST extended data item defined in a Standard 6128 ; Track or Experimental RFC. 6130 eitem-vendor-tag = vendor-token "-" atom 6131 ; a vendor-specific tag for LIST extended data item 6133 enable = "ENABLE" 1*(SP capability) 6135 enable-data = "ENABLED" *(SP capability) 6137 envelope = "(" env-date SP env-subject SP env-from SP 6138 env-sender SP env-reply-to SP env-to SP env-cc SP 6139 env-bcc SP env-in-reply-to SP env-message-id ")" 6141 env-bcc = "(" 1*address ")" / nil 6143 env-cc = "(" 1*address ")" / nil 6145 env-date = nstring 6147 env-from = "(" 1*address ")" / nil 6149 env-in-reply-to = nstring 6151 env-message-id = nstring 6153 env-reply-to = "(" 1*address ")" / nil 6155 env-sender = "(" 1*address ")" / nil 6157 env-subject = nstring 6159 env-to = "(" 1*address ")" / nil 6161 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 6162 *(SP search-return-data) 6163 ; ESEARCH response replaces SEARCH response 6164 ; from IMAP4rev1. 6166 examine = "EXAMINE" SP mailbox 6168 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 6169 fetch-att / "(" fetch-att *(SP fetch-att) ")") 6171 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 6172 "RFC822.SIZE" / 6173 "BODY" ["STRUCTURE"] / "UID" / 6174 "BODY" section [partial] / 6175 "BODY.PEEK" section [partial] / 6176 "BINARY" [".PEEK"] section-binary [partial] / 6177 "BINARY.SIZE" section-binary 6179 flag = "\Answered" / "\Flagged" / "\Deleted" / 6180 "\Seen" / "\Draft" / flag-keyword / flag-extension 6181 ; Does not include "\Recent" 6183 flag-extension = "\" atom 6184 ; Future expansion. Client implementations 6185 ; MUST accept flag-extension flags. Server 6186 ; implementations MUST NOT generate 6187 ; flag-extension flags except as defined by 6188 ; future standard or standards-track 6189 ; revisions of this specification. 6190 ; "\Recent" was defined in RFC 3501 6191 ; and is now deprecated. 6193 flag-fetch = flag 6195 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 6196 "$NotJunk" / "$Phishing" / atom 6198 flag-list = "(" [flag *(SP flag)] ")" 6200 flag-perm = flag / "\*" 6202 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 6204 header-fld-name = astring 6206 header-list = "(" header-fld-name *(SP header-fld-name) ")" 6208 idle = "IDLE" CRLF "DONE" 6210 initial-resp = (base64 / "=") 6211 ; "initial response" defined in 6212 ; Section 5.1 of [RFC4422] 6214 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 6215 [SP list-return-opts] 6217 list-mailbox = 1*list-char / string 6219 list-char = ATOM-CHAR / list-wildcards / resp-specials 6221 list-return-opts = "RETURN" SP 6222 "(" [return-option *(SP return-option)] ")" 6223 ; list return options, e.g., CHILDREN 6225 list-select-base-opt = "SUBSCRIBED" / option-extension 6226 ; options that can be used by themselves 6228 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 6230 list-select-independent-opt = "REMOTE" / option-extension 6231 ; options that do not syntactically interact with 6232 ; other options 6234 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 6235 ; options that require a list-select-base-opt 6236 ; to also be present 6238 list-select-opt = list-select-base-opt / list-select-independent-opt 6239 / list-select-mod-opt 6240 ; An option registration template is described in 6241 ; Section 9.3 of this document. 6243 list-select-opts = "(" [ 6244 (*(list-select-opt SP) list-select-base-opt 6245 *(SP list-select-opt)) 6246 / (list-select-independent-opt 6247 *(SP list-select-independent-opt)) 6248 ] ")" 6249 ; Any number of options may be in any order. 6250 ; If a list-select-mod-opt appears, then a 6251 ; list-select-base-opt must also appear. 6252 ; This allows these: 6253 ; () 6254 ; (REMOTE) 6255 ; (SUBSCRIBED) 6256 ; (SUBSCRIBED REMOTE) 6257 ; (SUBSCRIBED RECURSIVEMATCH) 6258 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6259 ; But does NOT allow these: 6260 ; (RECURSIVEMATCH) 6261 ; (REMOTE RECURSIVEMATCH) 6263 list-wildcards = "%" / "*" 6265 literal = "{" number64 ["+"] "}" CRLF *CHAR8 6266 ; represents the number of CHAR8s. 6267 ; A non-synchronizing literal is distinguished from 6268 ; a synchronizing literal by presence of the "+" 6269 ; before the closing "}". 6270 ; Non synchronizing literals are not allowed when 6271 ; sent from server to the client. 6273 literal8 = "~{" number64 "}" CRLF *OCTET 6274 ; represents the number of OCTETs 6275 ; in the response string. 6277 login = "LOGIN" SP userid SP password 6279 mailbox = "INBOX" / astring 6280 ; INBOX is case-insensitive. All case variants of 6281 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6282 ; not as an astring. An astring which consists of 6283 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6284 ; is considered to be INBOX and not an astring. 6285 ; Refer to section 5.1 for further 6286 ; semantic details of mailbox names. 6288 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6289 esearch-response / 6290 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6291 number SP "EXISTS" / Namespace-Response 6293 mailbox-list = "(" [mbx-list-flags] ")" SP 6294 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6295 [SP mbox-list-extended] 6296 ; This is the list information pointed to by the ABNF 6297 ; item "mailbox-data", which is defined in [IMAP4] 6299 mbox-list-extended = "(" [mbox-list-extended-item 6300 *(SP mbox-list-extended-item)] ")" 6302 mbox-list-extended-item = mbox-list-extended-item-tag SP 6303 tagged-ext-val 6305 mbox-list-extended-item-tag = astring 6306 ; The content MUST conform to either "eitem-vendor-tag" 6307 ; or "eitem-standard-tag" ABNF productions. 6309 mbox-or-pat = list-mailbox / patterns 6311 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6312 *(SP mbx-list-oflag) / 6313 mbx-list-oflag *(SP mbx-list-oflag) 6315 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6316 "\Subscribed" / "\Remote" / flag-extension 6317 ; Other flags; multiple possible per LIST response 6319 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6320 ; Selectability flags; only one per LIST response 6322 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6323 "FONT" / "MESSAGE" / "MODEL" / "VIDEO" ) DQUOTE) 6324 / string) 6325 SP media-subtype 6326 ; Defined in [MIME-IMT]. 6327 ; FONT defined in RFC 8081. 6329 media-message = DQUOTE "MESSAGE" DQUOTE SP 6330 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6331 ; Defined in [MIME-IMT] 6333 media-subtype = string 6334 ; Defined in [MIME-IMT] 6336 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6337 ; Defined in [MIME-IMT] 6339 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6341 move = "MOVE" SP sequence-set SP mailbox 6343 msg-att = "(" (msg-att-dynamic / msg-att-static) 6344 *(SP (msg-att-dynamic / msg-att-static)) ")" 6346 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6347 ; MAY change for a message 6349 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6350 "RFC822.SIZE" SP number64 / 6351 "BODY" ["STRUCTURE"] SP body / 6352 "BODY" section ["<" number ">"] SP nstring / 6353 "BINARY" section-binary SP (nstring / literal8) / 6354 "BINARY.SIZE" section-binary SP number / 6355 "UID" SP uniqueid 6356 ; MUST NOT change for a message 6358 name-component = 1*UTF8-CHAR 6359 ; MUST NOT contain ".", "/", "%", or "*" 6361 namespace = nil / "(" 1*namespace-descr ")" 6363 namespace-command = "NAMESPACE" 6365 namespace-descr = "(" string SP 6366 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6367 [namespace-response-extensions] ")" 6369 namespace-response-extensions = *namespace-response-extension 6371 namespace-response-extension = SP string SP 6372 "(" string *(SP string) ")" 6374 namespace-response = "NAMESPACE" SP namespace 6375 SP namespace SP namespace 6376 ; The first Namespace is the Personal Namespace(s). 6377 ; The second Namespace is the Other Users' 6378 ; Namespace(s). 6379 ; The third Namespace is the Shared Namespace(s). 6381 nil = "NIL" 6383 nstring = string / nil 6385 number = 1*DIGIT 6386 ; Unsigned 32-bit integer 6387 ; (0 <= n < 4,294,967,296) 6389 number64 = 1*DIGIT 6390 ; Unsigned 63-bit integer 6391 ; (0 <= n <= 9,223,372,036,854,775,807) 6393 nz-number = digit-nz *DIGIT 6394 ; Non-zero unsigned 32-bit integer 6395 ; (0 < n < 4,294,967,296) 6397 nz-number64 = digit-nz *DIGIT 6398 ; Unsigned 63-bit integer 6399 ; (0 < n <= 9,223,372,036,854,775,807) 6401 oldname-extended-item = "OLDNAME" SP "(" mailbox ")" 6402 ; Extended data item (mbox-list-extended-item) 6403 ; returned in a LIST response when a mailbox is 6404 ; renamed or deleted. Also returned when 6405 ; the server canonicalized the provided mailbox 6406 ; name. 6407 ; Note 1: the OLDNAME tag can be returned 6408 ; with or without surrounding quotes, as per 6409 ; mbox-list-extended-item-tag production. 6411 option-extension = (option-standard-tag / option-vendor-tag) 6412 [SP option-value] 6414 option-standard-tag = atom 6415 ; an option defined in a Standards Track or 6416 ; Experimental RFC 6418 option-val-comp = astring / 6419 option-val-comp *(SP option-val-comp) / 6420 "(" option-val-comp ")" 6422 option-value = "(" option-val-comp ")" 6424 option-vendor-tag = vendor-token "-" atom 6425 ; a vendor-specific option, non-standard 6427 partial-range = number64 ["." nz-number64] 6428 ; Copied from RFC 5092 (IMAP URL) 6429 ; and updated to support 64bit sizes. 6431 partial = "<" number64 "." nz-number64 ">" 6432 ; Partial FETCH request. 0-based offset of 6433 ; the first octet, followed by the number of octets 6434 ; in the fragment. 6436 password = astring 6438 patterns = "(" list-mailbox ")" 6439 ; [RFC5258] supports multiple patterns, 6440 ; but this document only requires one 6441 ; to be supported. 6442 ; If the server is also implementing 6443 ; [RFC5258], "patterns" syntax from that 6444 ; document must be followed. 6446 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6448 QUOTED-CHAR = / 6449 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6451 quoted-specials = DQUOTE / "\" 6453 rename = "RENAME" SP mailbox SP mailbox 6454 ; Use of INBOX as a destination gives a NO error 6456 response = *(continue-req / response-data) response-done 6458 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6459 mailbox-data / message-data / capability-data / 6460 enable-data) CRLF 6462 response-done = response-tagged / response-fatal 6464 response-fatal = "*" SP resp-cond-bye CRLF 6465 ; Server closes connection immediately 6467 response-tagged = tag SP resp-cond-state CRLF 6469 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6470 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6472 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6473 ; Authentication condition 6475 resp-cond-bye = "BYE" SP resp-text 6477 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6478 ; Status condition 6480 resp-specials = "]" 6482 resp-text = ["[" resp-text-code "]" SP] [text] 6484 resp-text-code = "ALERT" / 6485 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6486 capability-data / "PARSE" / 6487 "PERMANENTFLAGS" SP 6488 "(" [flag-perm *(SP flag-perm)] ")" / 6489 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6490 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6491 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6492 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6493 "AUTHORIZATIONFAILED" / "EXPIRED" / 6494 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6495 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6496 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6497 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6498 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6499 "CLOSED" / 6500 "UNKNOWN-CTE" / 6501 atom [SP 1*] 6503 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6504 option-extension 6506 search = "SEARCH" [search-return-opts] 6507 SP search-program 6509 search-correlator = SP "(" "TAG" SP tag-string ")" 6511 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6512 "BEFORE" SP date / "BODY" SP astring / 6513 "CC" SP astring / "DELETED" / "FLAGGED" / 6514 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6515 "ON" SP date / "SEEN" / 6516 "SINCE" SP date / "SUBJECT" SP astring / 6517 "TEXT" SP astring / "TO" SP astring / 6518 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6519 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6520 ; Above this line were in [IMAP2] 6521 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6522 "LARGER" SP number64 / "NOT" SP search-key / 6523 "OR" SP search-key SP search-key / 6524 "SENTBEFORE" SP date / "SENTON" SP date / 6525 "SENTSINCE" SP date / "SMALLER" SP number64 / 6526 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6527 "(" search-key *(SP search-key) ")" 6529 search-modifier-name = tagged-ext-label 6531 search-mod-params = tagged-ext-val 6532 ; This non-terminal shows recommended syntax 6533 ; for future extensions. 6535 search-program = ["CHARSET" SP charset SP] 6536 search-key *(SP search-key) 6537 ; CHARSET argument to SEARCH MUST be 6538 ; registered with IANA. 6540 search-ret-data-ext = search-modifier-name SP search-return-value 6541 ; Note that not every SEARCH return option 6542 ; is required to have the corresponding 6543 ; ESEARCH return data. 6545 search-return-data = "MIN" SP nz-number / 6546 "MAX" SP nz-number / 6547 "ALL" SP sequence-set / 6548 "COUNT" SP number / 6549 search-ret-data-ext 6550 ; All return data items conform to 6551 ; search-ret-data-ext syntax. 6552 ; Note that "$" marker is not allowed 6553 ; after the ALL return data item. 6555 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6556 *(SP search-return-opt)] ")" 6558 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6559 "SAVE" / 6560 search-ret-opt-ext 6561 ; conforms to generic search-ret-opt-ext 6562 ; syntax 6564 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6565 search-return-value = tagged-ext-val 6566 ; Data for the returned search option. 6567 ; A single "nz-number"/"number"/"number64" value 6568 ; can be returned as an atom (i.e., without 6569 ; quoting). A sequence-set can be returned 6570 ; as an atom as well. 6572 section = "[" [section-spec] "]" 6574 section-binary = "[" [section-part] "]" 6576 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6577 "TEXT" 6578 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6580 section-part = nz-number *("." nz-number) 6581 ; body part reference. 6582 ; Allows for accessing nested body parts. 6584 section-spec = section-msgtext / (section-part ["." section-text]) 6586 section-text = section-msgtext / "MIME" 6587 ; text other than actual body part (headers, etc.) 6589 select = "SELECT" SP mailbox 6591 seq-number = nz-number / "*" 6592 ; message sequence number (COPY, FETCH, STORE 6593 ; commands) or unique identifier (UID COPY, 6594 ; UID FETCH, UID STORE commands). 6595 ; * represents the largest number in use. In 6596 ; the case of message sequence numbers, it is 6597 ; the number of messages in a non-empty mailbox. 6598 ; In the case of unique identifiers, it is the 6599 ; unique identifier of the last message in the 6600 ; mailbox or, if the mailbox is empty, the 6601 ; mailbox's current UIDNEXT value. 6602 ; The server should respond with a tagged BAD 6603 ; response to a command that uses a message 6604 ; sequence number greater than the number of 6605 ; messages in the selected mailbox. This 6606 ; includes "*" if the selected mailbox is empty. 6608 seq-range = seq-number ":" seq-number 6609 ; two seq-number values and all values between 6610 ; these two regardless of order. 6611 ; Example: 2:4 and 4:2 are equivalent and indicate 6612 ; values 2, 3, and 4. 6614 ; Example: a unique identifier sequence range of 6615 ; 3291:* includes the UID of the last message in 6616 ; the mailbox, even if that value is less than 3291. 6618 sequence-set = (seq-number / seq-range) ["," sequence-set] 6619 ; set of seq-number values, regardless of order. 6620 ; Servers MAY coalesce overlaps and/or execute the 6621 ; sequence in any order. 6622 ; Example: a message sequence number set of 6623 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6624 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6625 ; Example: a message sequence number set of *:4,5:7 6626 ; for a mailbox with 10 messages is equivalent to 6627 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6628 ; overlap coalesced to be 4,5,6,7,8,9,10. 6630 sequence-set =/ seq-last-command 6631 ; Allow for "result of the last command" indicator. 6633 seq-last-command = "$" 6635 status = "STATUS" SP mailbox SP 6636 "(" status-att *(SP status-att) ")" 6638 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6639 "UNSEEN" / "DELETED" / "SIZE" 6641 status-att-val = ("MESSAGES" SP number) / 6642 ("UIDNEXT" SP nz-number) / 6643 ("UIDVALIDITY" SP nz-number) / 6644 ("UNSEEN" SP number) / 6645 ("DELETED" SP number) / 6646 ("SIZE" SP number64) 6647 ; Extensions to the STATUS responses 6648 ; should extend this production. 6649 ; Extensions should use the generic 6650 ; syntax defined by tagged-ext. 6652 status-att-list = status-att-val *(SP status-att-val) 6654 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6655 ; This ABNF production complies with 6656 ; syntax. 6658 store = "STORE" SP sequence-set SP store-att-flags 6660 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6661 (flag-list / (flag *(SP flag))) 6663 string = quoted / literal 6665 subscribe = "SUBSCRIBE" SP mailbox 6667 tag = 1* 6669 tag-string = astring 6670 ; represented as 6672 tagged-ext-label = tagged-label-fchar *tagged-label-char 6673 ; Is a valid RFC 3501 "atom". 6675 tagged-label-fchar = ALPHA / "-" / "_" / "." 6677 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6679 tagged-ext-comp = astring / 6680 tagged-ext-comp *(SP tagged-ext-comp) / 6681 "(" tagged-ext-comp ")" 6682 ; Extensions that follow this general 6683 ; syntax should use nstring instead of 6684 ; astring when appropriate in the context 6685 ; of the extension. 6686 ; Note that a message set or a "number" 6687 ; can always be represented as an "atom". 6688 ; An URL should be represented as 6689 ; a "quoted" string. 6691 tagged-ext-simple = sequence-set / number / number64 6693 tagged-ext-val = tagged-ext-simple / 6694 "(" [tagged-ext-comp] ")" 6696 text = 1*(TEXT-CHAR / UTF8-2 / UTF8-3 / UTF8-4) 6697 ; Non ASCII text can only be returned 6698 ; after ENABLE IMAP4rev2 command 6700 TEXT-CHAR = 6702 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6703 ; Hours minutes seconds 6705 uid = "UID" SP 6706 (copy / move / fetch / search / store / uid-expunge) 6707 ; Unique identifiers used instead of message 6708 ; sequence numbers 6710 uid-expunge = "EXPUNGE" SP sequence-set 6711 ; Unique identifiers used instead of message 6712 ; sequence numbers 6714 uid-set = (uniqueid / uid-range) *("," uid-set) 6716 uid-range = (uniqueid ":" uniqueid) 6717 ; two uniqueid values and all values 6718 ; between these two regards of order. 6719 ; Example: 2:4 and 4:2 are equivalent. 6721 uniqueid = nz-number 6722 ; Strictly ascending 6724 unsubscribe = "UNSUBSCRIBE" SP mailbox 6726 userid = astring 6728 UTF8-CHAR = 6730 UTF8-2 = 6732 UTF8-3 = 6734 UTF8-4 = 6736 vendor-token = "vendor." name-component 6737 ; Definition copied from RFC 2244. 6738 ; MUST be registered with IANA 6740 x-command = "X" atom 6742 zone = ("+" / "-") 4DIGIT 6743 ; Signed four-digit value of hhmm representing 6744 ; hours and minutes east of Greenwich (that is, 6745 ; the amount that the given time differs from 6746 ; Universal Time). Subtracting the timezone 6747 ; from the given time will give the UT form. 6748 ; The Universal Time zone is "+0000". 6750 10. Author's Note 6752 This document is a revision or rewrite of earlier documents, and 6753 supercedes the protocol specification in those documents: RFC 3501, 6754 RFC 2060, RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and 6755 RFC 1064. 6757 11. Security Considerations 6759 IMAP4rev2 protocol transactions, including electronic mail data, are 6760 sent in the clear over the network unless protection from snooping is 6761 negotiated. This can be accomplished either by the use of IMAPS 6762 service, STARTTLS command, negotiated privacy protection in the 6763 AUTHENTICATE command, or some other protection mechanism. 6765 11.1. TLS related Security Considerations 6767 This section applies to both use of STARTTLS command and Implicit TLS 6768 port. 6770 IMAP client and server implementations MUST comply with relevant TLS 6771 recommendations from [RFC8314]. 6773 Clients and servers MUST implement TLS 1.2 [TLS-1.2] or newer. Use 6774 of TLS 1.3 [TLS-1.3] is RECOMMENDED. TLS 1.2 may be used only in 6775 cases where the other party has not yet implemented TLS 1.3. 6776 Additionally, when using TLS 1.2, IMAP implementations MUST implement 6777 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite. This is 6778 important as it assures that any two compliant implementations can be 6779 configured to interoperate. Other TLS cipher suites recommended in 6780 RFC 7525 are RECOMMENDED: TLS_DHE_RSA_WITH_AES_128_GCM_SHA256, 6781 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6782 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6783 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6785 The list of mandatory-to-implement TLS 1.3 cipher suites is described 6786 in Section 9.1 of [TLS-1.3]. 6788 During the TLS negotiation [TLS-1.3][TLS-1.2], the client MUST check 6789 its understanding of the server hostname against the server's 6790 identity as presented in the server Certificate message, in order to 6791 prevent man-in-the-middle attacks. This procedure is described in 6792 [RFC7817]. 6794 Both the client and server MUST check the result of the STARTTLS 6795 command and subsequent TLS ([TLS-1.3][TLS-1.2]) negotiation to see 6796 whether acceptable authentication and/or privacy was achieved. 6798 11.2. STARTTLS command versa use of Implicit TLS port 6800 For maximum backward compatibility clients MUST implement both TLS 6801 negotiation using STARTTLS command and on implicit TLS port. 6803 Servers MUST support TLS negotiation on implicit TLS port and SHOULD 6804 support STARTTLS command. 6806 Some site/firewall maintainers insist on TLS site-wide and prefer not 6807 to rely on a configuration option in each higher-level protocol. For 6808 this reason, IMAP4rev2 clients SHOULD try both ports 993 and 143 (and 6809 both IPv4 and IPv6) concurrently by default, unless overriden by 6810 either user configuration or SRV records. Note that if a server 6811 answers on both ports, it MUST allow STARTTLS command on port 143. 6813 11.3. Client handling of unsolicited responses not suitable for the 6814 current connection state 6816 Cleartext mail transmission (whether caused by firewall configuration 6817 errors that result in TLS stripping or weak security policies in 6818 email clients that choose not to negotiate TLS in the first place) 6819 can enable injection of responses that can confuse or even cause 6820 crashes in email clients. The following measures are recommended to 6821 minimize damage from them. 6823 See Section 7.1.4 for special security considerations related to 6824 PREAUTH response. 6826 Many server responses and response codes are only meaningful in 6827 authenticated or even selected state. However, nothing prevents a 6828 server (or a man-in-the-middle attacker) from sending such invalid 6829 responses in cleartext before STARTTLS/AUTHENTICATE commands are 6830 issued. Before authentication clients SHOULD ignore any responses 6831 other than CAPABILITY and server status responses (Section 7.1), 6832 as well as any response codes other than CAPABILITY. Client 6833 SHOULD ignore the ALERT response code until after TLS has been 6834 successfully negotiated (whether using STARTTLS or TLS negotiation 6835 on implicit TLS port). Unless explicitly allowed by an IMAP 6836 extension, when not in selected state clients MUST ignore 6837 responses/response codes related to message and mailbox status 6838 such as FLAGS, EXIST, EXPUNGE and FETCH. 6840 11.4. COPYUID and APPENDUID response codes 6842 The COPYUID and APPENDUID response codes return information about the 6843 mailbox, which may be considered sensitive if the mailbox has 6844 permissions set that permit the client to COPY or APPEND to the 6845 mailbox, but not SELECT or EXAMINE it. 6847 Consequently, these response codes SHOULD NOT be issued if the client 6848 does not have access to SELECT or EXAMINE the mailbox. 6850 11.5. LIST command and Other Users' namespace 6852 In response to a LIST command containing an argument of the Other 6853 Users' Namespace prefix, a server SHOULD NOT list users that have not 6854 granted list access to their personal mailboxes to the currently 6855 authenticated user. Providing such a list, could compromise security 6856 by potentially disclosing confidential information of who is located 6857 on the server, or providing a starting point of a list of user 6858 accounts to attack. 6860 11.6. Other Security Considerations 6862 A server error message for an AUTHENTICATE command which fails due to 6863 invalid credentials SHOULD NOT detail why the credentials are 6864 invalid. 6866 Use of the LOGIN command sends passwords in the clear. This can be 6867 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6868 that does not use plaintext passwords, by first negotiating 6869 encryption via STARTTLS or some other protection mechanism. 6871 A server implementation MUST implement a configuration that, at the 6872 time of authentication, requires: 6873 (1) The STARTTLS command has been negotiated or TLS negotiated on 6874 implicit TLS port. 6875 OR 6876 (2) Some other mechanism that protects the session from password 6877 snooping has been provided. 6878 OR 6879 (3) The following measures are in place: 6880 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6881 (such as PLAIN) using plaintext passwords are NOT advertised in the 6882 CAPABILITY list. 6883 AND 6884 (b) The LOGIN command returns an error even if the password is 6885 correct. 6886 AND 6887 (c) The AUTHENTICATE command returns an error with all [SASL] 6888 mechanisms that use plaintext passwords, even if the password is 6889 correct. 6891 A server error message for a failing LOGIN command SHOULD NOT specify 6892 that the user name, as opposed to the password, is invalid. 6894 A server SHOULD have mechanisms in place to limit or delay failed 6895 AUTHENTICATE/LOGIN attempts. 6897 A server SHOULD report any authentication failure and analyze such 6898 authentication failure attempt with regard to a password brute force 6899 attack as well as a password spraying attack. Accounts that match 6900 password spraying attacks MUST be blocked and request to change their 6901 passwords and only password with significant strength SHOULD be 6902 accepted. 6904 Additional security considerations are discussed in the section 6905 discussing the AUTHENTICATE (see Section 6.2.2) and LOGIN (see 6906 Section 6.2.3) commands. 6908 12. IANA Considerations 6910 IANA is requested to update "Service Names and Transport Protocol 6911 Port Numbers" registry as follows: 6913 1. Registration for TCP port 143 and the corresponding "imap" 6914 service name should be updated to point to this document and RFC 6915 3501. 6917 2. Registration for TCP port 993 and the corresponding "imaps" 6918 service name should be updated to point to this document, RFC 6919 8314 and RFC 3501. 6921 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6922 in the registry. 6924 Additional IANA actions are specified in subsection of this section. 6926 12.1. Updates to IMAP4 Capabilities registry 6928 IMAP4 capabilities are registered by publishing a standards track or 6929 IESG approved informational or experimental RFC. The registry is 6930 currently located at: https://www.iana.org/assignments/ 6931 imap4-capabilities 6933 As this specification revises the AUTH= prefix, STARTTLS and 6934 LOGINDISABLED extensions, IANA is requested to update registry 6935 entries for these 3 extensions to point to this document and RFC 6936 3501. 6938 12.2. GSSAPI/SASL service name 6940 GSSAPI/Kerberos/SASL service names are registered by publishing a 6941 standards track or IESG approved experimental RFC. The registry is 6942 currently located at: https://www.iana.org/assignments/gssapi- 6943 service-names 6944 IANA is requested to update the "imap" service name previously 6945 registered in RFC 3501, to point to both this document and RFC 3501. 6947 12.3. LIST Selection Options, LIST Return Options, LIST extended data 6948 items 6950 [RFC5258] specifies IANA registration procedures for LIST Selection 6951 Options, LIST Return Options, LIST extended data items. This 6952 document doesn't change these registration procedures. In particular 6953 LIST selection options (Section 6.3.9.1) and LIST return options 6954 (Section 6.3.9.2) are registered using the procedure specified in 6955 Section 9 of [RFC5258] (and using the registration template from 6956 Section 9.3 of [RFC5258]). LIST Extended Data Items are registered 6957 using the registration template from Section 9.6 of [RFC5258]). 6959 IANA is requested to add a reference to [RFCXXXX] for the "OLDNAME" 6960 LIST-EXTENDED extended data item entry. This is in addition to the 6961 existing reference to [RFC5465]. 6963 12.4. IMAP Mailbox Name Attributes and IMAP Response Codes 6965 IANA is requested to update the "IMAP Mailbox Name Attributes" 6966 registry to point to this document in addition to RFC 3501. 6968 IANA is requested to update the "IMAP Response Codes" registry to 6969 point to this document in addition to RFC 3501. 6971 13. References 6973 13.1. Normative References 6975 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6976 Protocol version 4 - LIST Command Extensions", RFC 5258, 6977 DOI 10.17487/RFC5258, June 2008, 6978 . 6980 [RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", 6981 RFC 5788, DOI 10.17487/RFC5788, March 2010, 6982 . 6984 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6985 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6986 . 6988 [ANONYMOUS] 6989 Zeilenga, K., "Anonymous Simple Authentication and 6990 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6991 . 6993 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6994 Procedures", BCP 19, RFC 2978, October 2000, 6995 . 6997 [SCRAM-SHA-256] 6998 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6999 Authentication and Security Layer (SASL) Mechanisms", 7000 RFC 7677, DOI 10.17487/RFC7677, November 2015, 7001 . 7003 [DISPOSITION] 7004 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 7005 Presentation Information in Internet Messages: The 7006 Content-Disposition Header Field", RFC 2183, August 1997, 7007 . 7009 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 7010 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 7011 . 7013 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 7014 Requirement Levels", BCP 14, RFC 2119, 7015 DOI 10.17487/RFC2119, March 1997, 7016 . 7018 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 7019 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 7020 May 2017, . 7022 [LANGUAGE-TAGS] 7023 Alvestrand, H., "Content Language Headers", RFC 3282, May 7024 2002, . 7026 [LOCATION] 7027 Palme, J., Hopmann, A., and N. Shelness, "MIME 7028 Encapsulation of Aggregate Documents, such as HTML 7029 (MHTML)", RFC 2557, March 1999, 7030 . 7032 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 7033 RFC 1864, October 1995, 7034 . 7036 [MIME-HDRS] 7037 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 7038 Part Three: Message Header Extensions for Non-ASCII Text", 7039 RFC 2047, November 1996, 7040 . 7042 [MIME-IMB] 7043 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 7044 Extensions (MIME) Part One: Format of Internet Message 7045 Bodies", RFC 2045, November 1996, 7046 . 7048 [MIME-IMT] 7049 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 7050 Extensions (MIME) Part Two: Media Types", RFC 2046, 7051 November 1996, . 7053 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 7054 Word Extensions: Character Sets, Languages, and 7055 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 7056 1997, . 7058 [RFC-5322] 7059 Resnick, P., Ed., "Internet Message Format", RFC 5322, 7060 October 2008, . 7062 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 7063 Authentication and Security Layer (SASL)", RFC 4422, June 7064 2006, . 7066 [TLS-1.2] Dierks, T. and E. Rescorla, "The Transport Layer Security 7067 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 7068 . 7070 [TLS-1.3] Rescorla, E., "The Transport Layer Security (TLS) Protocol 7071 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 7072 . 7074 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 7075 Transformation Format of Unicode", RFC 2152, May 1997, 7076 . 7078 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 7079 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 7080 2003, . 7082 [MULTIAPPEND] 7083 Crispin, M., "Internet Message Access Protocol (IMAP) - 7084 MULTIAPPEND Extension", RFC 3502, March 2003, 7085 . 7087 [NET-UNICODE] 7088 Klensin, J. and M. Padlipsky, "Unicode Format for Network 7089 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 7090 . 7092 [I18N-HDRS] 7093 Yang, A., Steele, S., and N. Freed, "Internationalized 7094 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 7095 2012, . 7097 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 7098 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 7099 . 7101 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 7102 Server Identity Check Procedure for Email-Related 7103 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 7104 . 7106 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 7107 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 7108 February 2017, . 7110 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 7111 Use of Transport Layer Security (TLS) for Email Submission 7112 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 7113 . 7115 [IMAP-IMPLEMENTATION] 7116 Leiba, B., "IMAP4 Implementation Recommendations", 7117 RFC 2683, September 1999, 7118 . 7120 [IMAP-MULTIACCESS] 7121 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 7122 RFC 2180, July 1997, 7123 . 7125 13.2. Informative References (related protocols) 7127 [CERT-555316] 7128 CERT, "Vulnerability Note VU#555316: STARTTLS plaintext 7129 command injection vulnerability", September 2011, 7130 . 7132 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 7133 profile for Internet Message Access Protocol (IMAP)", 7134 RFC 3503, DOI 10.17487/RFC3503, March 2003, 7135 . 7137 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 7138 Protocol - SORT and THREAD Extensions", RFC 5256, 7139 DOI 10.17487/RFC5256, June 2008, 7140 . 7142 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 7143 DOI 10.17487/RFC2193, September 1997, 7144 . 7146 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 7147 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 7148 DOI 10.17487/RFC3348, July 2002, 7149 . 7151 [RFC5465] Gulbrandsen, A., King, C., and A. Melnikov, "The IMAP 7152 NOTIFY Extension", RFC 5465, DOI 10.17487/RFC5465, 7153 February 2009, . 7155 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 7156 RFC 7888, DOI 10.17487/RFC7888, May 2016, 7157 . 7159 [IMAP-DISC] 7160 Melnikov, A., Ed., "Synchronization Operations for 7161 Disconnected IMAP4 Clients", RFC 4549, June 2006, 7162 . 7164 [IMAP-I18N] 7165 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 7166 Message Access Protocol Internationalization", RFC 5255, 7167 DOI 10.17487/RFC5255, June 2008, 7168 . 7170 [IMAP-MODEL] 7171 Crispin, M., "Distributed Electronic Mail Models in 7172 IMAP4", RFC 1733, December 1994, 7173 . 7175 [IMAP-UTF-8] 7176 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 7177 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 7178 2013, . 7180 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 7181 October 2008, . 7183 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 7184 DOI 10.17487/RFC3516, April 2003, 7185 . 7187 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 7188 RFC 4314, December 2005, 7189 . 7191 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 7192 1997, . 7194 [IMAP-URL] 7195 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 7196 RFC 5092, DOI 10.17487/RFC5092, November 2007, 7197 . 7199 [IMAP-KEYWORDS-REG] 7200 IANA, "IMAP and JMAP Keywords", December 2009, 7201 . 7204 [IMAP-MAILBOX-NAME-ATTRS-REG] 7205 IANA, "IMAP Mailbox Name Attributes", June 2018, 7206 . 7209 [CHARSET-REG] 7210 IANA, "Character Set Registrations", May 2015, 7211 . 7214 13.3. Informative References (historical aspects of IMAP and related 7215 protocols) 7217 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 7218 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 7219 . 7221 [IMAP-COMPAT] 7222 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 7223 RFC 2061, December 1996, 7224 . 7226 [IMAP-HISTORICAL] 7227 Crispin, M., "IMAP4 Compatibility with IMAP2 and 7228 IMAP2bis", RFC 1732, December 1994, 7229 . 7231 [IMAP-OBSOLETE] 7232 Crispin, M., "Internet Message Access Protocol - Obsolete 7233 Syntax", RFC 2062, December 1996, 7234 . 7236 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 7237 2", RFC 1176, August 1990, 7238 . 7240 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 7241 TEXT MESSAGES", STD 11, RFC 822, August 1982, 7242 . 7244 [IMAP-TLS] 7245 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 7246 RFC 2595, June 1999, 7247 . 7249 Appendix A. Backward compatibility with IMAP4rev1 7251 An implementation that wants to remain compatible with IMAP4rev1 can 7252 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 7253 response code. While some IMAP4rev1 responses were removed in 7254 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 7256 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 7257 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 7259 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 7260 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 7261 Consider implementation of mechanisms described or referenced in 7262 [IMAP-UTF-8] to achieve this goal. 7264 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 7265 intending to be compatible with IMAP4rev1 servers MUST be compatible 7266 with the international mailbox naming convention described in the 7267 following subsection. 7269 Also see Appendix D for special considerations for servers that 7270 support 63 bit body part/message sizes and want to advertise support 7271 for both IMAP4rev1 and IMAP4rev2. 7273 A.1. Mailbox International Naming Convention for compatibility with 7274 IMAP4rev1 7276 Support for the Mailbox International Naming Convention described in 7277 this section is not required for IMAP4rev2-only clients and servers. 7278 It is only used for backward compatibility with IMAP4rev1 7279 implementations. 7281 By convention, international mailbox names in IMAP4rev1 are specified 7282 using a modified version of the UTF-7 encoding described in [UTF-7]. 7283 Modified UTF-7 may also be usable in servers that implement an 7284 earlier version of this protocol. 7286 In modified UTF-7, printable US-ASCII characters, except for "&", 7287 represent themselves; that is, characters with octet values 0x20-0x25 7288 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 7289 octet sequence "&-". 7291 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 7292 represented in modified BASE64, with a further modification from 7293 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 7294 used to represent any printing US-ASCII character which can represent 7295 itself. Only characters inside the modified BASE64 alphabet are 7296 permitted in modified BASE64 text. 7298 "&" is used to shift to modified BASE64 and "-" to shift back to US- 7299 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 7300 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 7301 "&") are not permitted. However, all names start in US-ASCII, and 7302 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 7303 ISO-10646 character MUST end with a "-"). 7305 The purpose of these modifications is to correct the following 7306 problems with UTF-7: 7308 1. UTF-7 uses the "+" character for shifting; this conflicts with 7309 the common use of "+" in mailbox names, in particular USENET 7310 newsgroup names. 7312 2. UTF-7's encoding is BASE64 which uses the "/" character; this 7313 conflicts with the use of "/" as a popular hierarchy delimiter. 7315 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 7316 the use of "\" as a popular hierarchy delimiter. 7318 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 7319 the use of "~" in some servers as a home directory indicator. 7321 5. UTF-7 permits multiple alternate forms to represent the same 7322 string; in particular, printable US-ASCII characters can be 7323 represented in encoded form. 7325 Although modified UTF-7 is a convention, it establishes certain 7326 requirements on server handling of any mailbox name with an embedded 7327 "&" character. In particular, server implementations MUST preserve 7328 the exact form of the modified BASE64 portion of a modified UTF-7 7329 name and treat that text as case-sensitive, even if names are 7330 otherwise case-insensitive or case-folded. 7332 Server implementations SHOULD verify that any mailbox name with an 7333 embedded "&" character, used as an argument to CREATE, is: in the 7334 correctly modified UTF-7 syntax, has no superfluous shifts, and has 7335 no encoding in modified BASE64 of any printing US-ASCII character 7336 which can represent itself. However, client implementations MUST NOT 7337 depend upon the server doing this, and SHOULD NOT attempt to create a 7338 mailbox name with an embedded "&" character unless it complies with 7339 the modified UTF-7 syntax. 7341 Server implementations which export a mail store that does not follow 7342 the modified UTF-7 convention MUST convert to modified UTF-7 any 7343 mailbox name that contains either non-ASCII characters or the "&" 7344 character. 7346 For example, here is a mailbox name which mixes English, Chinese, 7347 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 7349 For example, the string "&Jjo!" is not a valid mailbox name 7350 because it does not contain a shift to US-ASCII before the "!". 7351 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 7352 not permitted because it contains a superfluous shift. The 7353 correct form is "&U,BTF2XlZyyKng-". 7355 Appendix B. Backward compatibility with BINARY extension 7357 IMAP4rev2 incorporates subset of functionality provided by the BINARY 7358 extension [RFC3516], in particular it includes additional FETCH items 7359 (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions to the 7360 APPEND command. IMAP4rev2 implementations that supports full RFC 7361 3516 functionality need to also advertise the BINARY capability in 7362 the CAPABILITY response/response code. 7364 Appendix C. Backward compatibility with LIST-EXTENDED extension 7366 IMAP4rev2 incorporates most of functionality provided by the LIST- 7367 EXTENDED extension [RFC5258]. In particular, multiple mailbox 7368 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 7369 capability is also advertised in the CAPABILITY response/response 7370 code. 7372 Appendix D. 63 bit body part and message sizes 7374 IMAP4rev2 increases allowed body part and message sizes that servers 7375 can support from 32 to 63 bits. Server implementations don't have to 7376 support 63 bit long body parts/message sizes, however client 7377 implementations have to expect them. 7379 As IMAP4rev1 didn't support 63 bit long body part/message sizes, 7380 there is an interoperability issue exposed by 63 bit capable servers 7381 that are accessible by both IMAP4rev1 and IMAP4rev2 email clients. 7382 As IMAP4rev1 would be unable to retrieve full content of messages 7383 bigger than 4Gb, such servers either need to replace messages bigger 7384 that 4Gb with messages under 4Gb or hide them from IMAP4rev1 clients. 7385 This document doesn't prescribe any implementation strategy to 7386 address this issue. 7388 Appendix E. Changes from RFC 3501 / IMAP4rev1 7390 Below is the summary of changes since RFC 3501: 7392 1. Support for 64bit message and body part sizes. 7394 2. Folded in IMAP NAMESPACE (RFC 2342), UNSELECT (RFC 3691), 7395 UIDPLUS (RFC 4315), ESEARCH (RFC 4731), SEARCHRES (RFC 5182), 7396 ENABLE (RFC 5161), IDLE (RFC 2177), SASL-IR (RFC 4959), LIST- 7397 EXTENDED (RFC 5258), LIST-STATUS (RFC 5819), MOVE (RFC 6851) and 7398 LITERAL- (RFC 7888) extensions. Also folded RFC 4466 (IMAP ABNF 7399 extensions), RFC 5530 (response codes), the FETCH side of the 7400 BINARY extension (RFC 3516) and the list of new mailbox 7401 attributes from SPECIAL-USE (RFC 6154). 7403 3. Added STATUS SIZE (RFC 8438) and STATUS DELETED. 7405 4. SEARCH command now requires to return ESEARCH response (SEARCH 7406 response is now deprecated). 7408 5. Clarified which SEARCH keys have to use substring match and 7409 which don't. 7411 6. Clarified that server should decode parameter value 7412 continuations as described in [RFC2231]. This requirement was 7413 hidden in RFC 2231 itself. 7415 7. Clarified that COPYUID response code is returned for both MOVE 7416 and UID MOVE. 7418 8. Tighen requirements about COPY/MOVE commands not creating target 7419 mailbox. Also require them to return TRYCREATE response code, 7420 if the target mailbox doesn't exist and can be created. 7422 9. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7423 mailbox is already selected now requires a CLOSED response code 7424 to be returned. 7426 10. SELECT/EXAMINE are now required to return untagged LIST 7427 response. 7429 11. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7431 12. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7432 SEARCH NEW items are now deprecated. 7434 13. Clarified that the server doesn't need to send a new 7435 PERMANENTFLAGS response code when a new keyword was successfully 7436 added and the server advertised \* earlier for the same mailbox. 7438 14. For future extensibility extended ABNF for tagged-ext-simple to 7439 allow for bare number64. 7441 15. Added SHOULD level requirement on IMAP servers to support 7442 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7444 16. Mailbox names and message headers now allow for UTF-8. Support 7445 for Modified UTF-7 in mailbox names is not required, unless 7446 compatibility with IMAP4rev1 is desired. 7448 17. Removed the CHECK command. Clients should use NOOP instead. 7450 18. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7451 deprecated. Clients should use the corresponding BODY[] 7452 variants instead. 7454 19. LSUB command was deprecated. Clients should use LIST 7455 (SUBSCRIBED) instead. 7457 20. IDLE command can now return updates not related to the currently 7458 selected mailbox state. 7460 21. All unsolicited FETCH updates are required to include UID. 7462 22. Clarified that client implementations MUST ignore response codes 7463 that they do not recognize. (Change from a SHOULD to a MUST.) 7465 23. resp-text ABNF non terminal was updated to allow for empty text. 7467 24. After ENABLE IMAP4rev2 human readable response text can include 7468 non ASCII encoded in UTF-8. 7470 25. Updated to use modern TLS-related recommendations as per RFC 7471 8314, RFC 7817, RFC 7525. 7473 26. Added warnings about use of ALERT response codes and PREAUTH 7474 response. 7476 27. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7477 MD5 was deprecated. 7479 28. Clarified that any command received from the client resets 7480 server autologout timer. 7482 29. Revised IANA registration procedure for IMAP extensions and 7483 removed "X" convention. 7485 30. Loosened requirements on servers when closing connections to be 7486 more aligned with existing practices. 7488 Appendix F. Other Recommended IMAP Extensions 7490 Support for the following extensions is recommended for all IMAP 7491 client and servers. While they significantly reduce bandwidth and/or 7492 number of round trips used by IMAP in certain situations, the EXTRA 7493 WG decided that requiring them as a part of IMAP4rev2 would push the 7494 bar to implement too high for new implementations. Also note that 7495 absence of any IMAP extension from this list doesn't make it somehow 7496 deficient or not recommended for use with IMAP4rev2. 7498 1. QRESYNC and CONDSTORE extensions (RFC 7162). They make 7499 discovering changes to IMAP mailboxes more efficient, at the 7500 expense of storing a bit more state. 7502 2. OBJECTID extension (RFC 8474) helps with preserving IMAP client 7503 cache when messages moved/copied or mailboxes are renamed. 7505 Appendix G. Acknowledgement 7507 Earlier versions of this document were edited by Mark Crispin. 7508 Sadly, he is no longer available to help with this work. Editors of 7509 this revisions are hoping that Mark would have approved. 7511 Chris Newman has contributed text on I18N and use of UTF-8 in 7512 messages and mailbox names. 7514 Thank you to Tony Hansen for helping with the index generation. 7515 Thank you to Murray Kucherawy, Timo Sirainen, Bron Gondwana, Stephan 7516 Bosch, Robert Sparks, Arnt Gulbrandsen and Daniel Migault for 7517 extensive feedback. 7519 This document incorporates text from RFC 4315 (by Mark Crispin), RFC 7520 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7521 Gulbrandsen), RFC 5465 (by Arnt Gulbrandsen and Curtis King), RFC 7522 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo Sirainen), RFC 6154 (by 7523 Jamie Nicolson), RFC 8438 (by Stephan Bosch) so work done by authors/ 7524 editors of these documents is appreciated. Note that editors of this 7525 document were redacted from the above list. 7527 The CHILDREN return option was originally proposed by Mike Gahrns and 7528 Raymond Cheng in [RFC3348]. Most of the information in 7529 Section 6.3.9.5 is taken directly from their original specification 7530 [RFC3348]. 7532 Thank you to Damian Poddebniak, Fabian Ising, Hanno Boeck and 7533 Sebastian Schinzel for pointing out that the ENABLE command should be 7534 a member of "command-auth" and not "command-any" ABNF production, as 7535 well as pointing out security issues associated with ALERT, PREAUTH 7536 and other responses received before authentication. 7538 Index 7540 $ 7541 $Forwarded (predefined flag) 12 7542 $Junk (predefined flag) 13 7543 $MDNSent (predefined flag) 13 7544 $NotJunk (predefined flag) 13 7545 $Phishing (predefined flag) 13 7547 + 7548 +FLAGS 93 7549 +FLAGS.SILENT 93 7551 - 7552 -FLAGS 93 7553 -FLAGS.SILENT 93 7555 A 7556 ALERT (response code) 101 7557 ALL (fetch item) 89 7558 ALL (search key) 79 7559 ALL (search result option) 77 7560 ALREADYEXISTS (response code) 101 7561 ANSWERED (search key) 79 7562 APPEND (command) 69 7563 APPENDUID (response code) 101 7564 AUTHENTICATE (command) 30 7565 AUTHENTICATIONFAILED (response code) 102 7566 AUTHORIZATIONFAILED (response code) 102 7568 B 7569 BAD (response) 109 7570 BADCHARSET (response code) 102 7571 BCC (search key) 79 7572 BEFORE (search key) 79 7573 BINARY.PEEK[]<> (fetch item) 89 7574 BINARY.SIZE[] (fetch item) 90 7575 BINARY.SIZE[] (fetch result) 120 7576 BINARY[]<> (fetch result) 119 7577 BINARY[]<> (fetch item) 89 7578 BODY (fetch item) 90 7579 BODY (fetch result) 120 7580 BODY (search key) 79 7581 BODY.PEEK[
]<> (fetch item) 90 7582 BODYSTRUCTURE (fetch item) 91 7583 BODYSTRUCTURE (fetch result) 121 7584 BODY[
]<> (fetch result) 120 7585 BODY[
]<> (fetch item) 90 7586 BYE (response) 110 7587 Body Structure (message attribute) 14 7589 C 7590 CANNOT (response code) 102 7591 CAPABILITY (command) 26 7592 CAPABILITY (response code) 103 7593 CAPABILITY (response) 111 7594 CC (search key) 79 7595 CLIENTBUG (response code) 103 7596 CLOSE (command) 75 7597 CLOSED (response code) 103 7598 CONTACTADMIN (response code) 103 7599 COPY (command) 94 7600 COPYUID (response code) 103 7601 CORRUPTION (response code) 104 7602 COUNT (search result option) 77 7603 CREATE (command) 39 7605 D 7606 DELETE (command) 40 7607 DELETED (search key) 79 7608 DELETED (status item) 69 7609 DRAFT (search key) 79 7611 E 7612 ENABLE (command) 34 7613 ENVELOPE (fetch item) 91 7614 ENVELOPE (fetch result) 123 7615 ESEARCH (response) 117 7616 EXAMINE (command) 38 7617 EXPIRED (response code) 104 7618 EXPUNGE (command) 76 7619 EXPUNGE (response) 118 7620 EXPUNGEISSUED (response code) 104 7621 Envelope Structure (message attribute) 14 7623 F 7624 FAST (fetch item) 89 7625 FETCH (command) 88 7626 FETCH (response) 119 7627 FLAGGED (search key) 79 7628 FLAGS (fetch item) 91 7629 FLAGS (fetch result) 125 7630 FLAGS (response) 117 7631 FLAGS (store command data item) 93 7632 FLAGS.SILENT (store command data item) 93 7633 FROM (search key) 79 7634 FULL (fetch item) 89 7635 Flags (message attribute) 12 7637 H 7638 HASCHILDREN (response code) 105 7639 HEADER (part specifier) 91 7640 HEADER (search key) 80 7641 HEADER.FIELDS (part specifier) 91 7642 HEADER.FIELDS.NOT (part specifier) 91 7644 I 7645 IDLE (command) 72 7646 INTERNALDATE (fetch item) 91 7647 INTERNALDATE (fetch result) 125 7648 INUSE (response code) 105 7649 Internal Date (message attribute) 14 7651 K 7652 KEYWORD (search key) 80 7653 Keyword (type of flag) 12 7655 L 7656 LARGER (search key) 80 7657 LIMIT (response code) 105 7658 LIST (command) 45 7659 LIST (response) 112 7660 LOGOUT (command) 27 7662 M 7663 MAX (search result option) 77 7664 MAY (specification requirement term) 5 7665 MESSAGES (status item) 69 7666 MIME (part specifier) 92 7667 MIN (search result option) 77 7668 MOVE (command) 95 7669 MUST (specification requirement term) 5 7670 MUST NOT (specification requirement term) 5 7671 Message Sequence Number (message attribute) 11 7673 N 7674 NAMESPACE (command) 63 7675 NAMESPACE (response) 116 7676 NO (response) 109 7677 NONEXISTENT (response code) 105 7678 NOOP (command) 27 7679 NOPERM (response code) 105 7680 NOT (search key) 80 7681 NOT RECOMMENDED (specification requirement term) 5 7683 O 7684 OK (response) 108 7685 ON (search key) 80 7686 OPTIONAL (specification requirement term) 5 7687 OR (search key) 80 7688 OVERQUOTA (response code) 106 7690 P 7691 PARSE (response code) 106 7692 PERMANENTFLAGS (response code) 106 7693 PREAUTH (response) 110 7694 PRIVACYREQUIRED (response code) 106 7695 Permanent Flag (class of flag) 13 7696 Predefined keywords 12 7698 R 7699 READ-ONLY (response code) 107 7700 READ-WRITE (response code) 107 7701 RECOMMENDED (specification requirement term) 5 7702 RENAME (command) 42 7703 REQUIRED (specification requirement term) 5 7704 RFC822.SIZE (fetch item) 91 7705 RFC822.SIZE (fetch result) 125 7707 S 7708 SAVE (search result option) 77 7709 SEARCH (command) 76 7710 SEEN (search key) 80 7711 SELECT (command) 36 7712 SENTBEFORE (search key) 80 7713 SENTON (search key) 80 7714 SENTSINCE (search key) 80 7715 SERVERBUG (response code) 107 7716 SHOULD (specification requirement term) 5 7717 SHOULD NOT (specification requirement term) 5 7718 SINCE (search key) 80 7719 SIZE (status item) 69 7720 SMALLER (search key) 80 7721 STARTTLS (command) 28 7722 STATUS (command) 68 7723 STATUS (response) 117 7724 STORE (command) 93 7725 SUBJECT (search key) 80 7726 SUBSCRIBE (command) 44 7727 Session Flag (class of flag) 13 7728 System Flag (type of flag) 12 7730 T 7731 TEXT (part specifier) 91 7732 TEXT (search key) 81 7733 TO (search key) 81 7734 TRYCREATE (response code) 107 7736 U 7737 UID (command) 97 7738 UID (fetch item) 91 7739 UID (fetch result) 125 7740 UID (search key) 81 7741 UIDNEXT (response code) 107 7742 UIDNEXT (status item) 69 7743 UIDNOTSTICKY (response code) 107 7744 UIDVALIDITY (response code) 108 7745 UIDVALIDITY (status item) 69 7746 UNANSWERED (search key) 81 7747 UNAVAILABLE (response code) 108 7748 UNDELETED (search key) 81 7749 UNDRAFT (search key) 81 7750 UNFLAGGED (search key) 81 7751 UNKEYWORD (search key) 81 7752 UNKNOWN-CTE (response code) 108 7753 UNSEEN (search key) 81 7754 UNSEEN (status item) 69 7755 UNSELECT (command) 75 7756 UNSUBSCRIBE (command) 45 7757 Unique Identifier (UID) (message attribute) 9 7759 [ 7760 [RFC-5322] Size (message attribute) 14 7762 \ 7763 \All (mailbox name attribute) 114 7764 \Answered (system flag) 12 7765 \Archive (mailbox name attribute) 114 7766 \Deleted (system flag) 12 7767 \Draft (system flag) 12 7768 \Drafts (mailbox name attribute) 115 7769 \Flagged (mailbox name attribute) 115 7770 \Flagged (system flag) 12 7771 \HasChildren (mailbox name attribute) 113 7772 \HasNoChildren (mailbox name attribute) 113 7773 \Junk (mailbox name attribute) 115 7774 \Marked (mailbox name attribute) 114 7775 \Noinferiors (mailbox name attribute) 113 7776 \NonExistent (mailbox name attribute) 113 7777 \Noselect (mailbox name attribute) 113 7778 \Recent (system flag) 12 7779 \Remote (mailbox name attribute) 114 7780 \Seen (system flag) 12 7781 \Sent (mailbox name attribute) 115 7782 \Subscribed (mailbox name attribute) 114 7783 \Trash (mailbox name attribute) 115 7784 \Unmarked (mailbox name attribute) 114 7786 Authors' Addresses 7788 Alexey Melnikov (editor) 7789 Isode Ltd 7790 14 Castle Mews 7791 Hampton, Middlesex TW12 2NP 7792 UK 7794 Email: Alexey.Melnikov@isode.com 7796 Barry Leiba (editor) 7797 Futurewei Technologies 7799 Phone: +1 646 827 0648 7800 Email: barryleiba@computer.org 7801 URI: http://internetmessagingtechnology.org/