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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 4, 2021) is 1202 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 7090, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 7085, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 7075, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 7080, but not defined == Missing Reference: 'RFC-822' is mentioned on line 7094, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 7024, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 7013, but not defined == Missing Reference: 'RFC3503' is mentioned on line 6986, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 7053, but not defined == Missing Reference: 'SMTP' is mentioned on line 7034, but not defined == Missing Reference: 'RFC7888' is mentioned on line 7009, but not defined -- Looks like a reference, but probably isn't: '1' on line 897 == Missing Reference: 'IMAP-URL' is mentioned on line 7048, but not defined == Missing Reference: 'TLS' is mentioned on line 1205, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5784, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1743, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6996, but not defined == Missing Reference: 'RFC3348' is mentioned on line 7364, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 7041, but not defined == Missing Reference: 'RFC3501' is mentioned on line 7071, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3277, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3349, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 7063, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 7018, but not defined == Missing Reference: 'HEADER' is mentioned on line 5802, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3929, but not defined == Missing Reference: 'UID' is mentioned on line 4357, but not defined == Missing Reference: 'RFC2087' is mentioned on line 7045, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 7058, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5786, but not defined == Missing Reference: 'RFC4422' is mentioned on line 6133, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6218, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6288, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 7098, but not defined == Missing Reference: 'RFCXXXX' is mentioned on line 6826, but not defined == Missing Reference: 'RFC5465' is mentioned on line 7005, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6991, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 7116, but not defined == Missing Reference: 'RFC3516' is mentioned on line 7212, 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 8, 2021 January 4, 2021 8 Internet Message Access Protocol (IMAP) - Version 4rev2 9 draft-ietf-extra-imap4rev2-23 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 8, 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 . . . . . . . . . . . . . . . 11 90 2.3.3. Internal Date Message Attribute . . . . . . . . . . . 13 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 . . . . . . . . . . . . . . . . . 14 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) . . . 23 116 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 117 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 25 118 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 25 119 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 26 120 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 121 6.2. Client Commands - Not Authenticated State . . . . . . . . 27 122 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 28 123 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 29 124 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 32 125 6.3. Client Commands - Authenticated State . . . . . . . . . . 33 126 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 33 127 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 35 128 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 37 129 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 38 130 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 39 131 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 41 132 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 43 133 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 44 134 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 44 135 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 63 136 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 67 137 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 68 138 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 71 139 6.4. Client Commands - Selected State . . . . . . . . . . . . 73 140 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 74 141 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 74 142 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 75 143 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 75 144 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 87 145 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 92 146 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 93 147 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 94 148 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 96 149 6.5. Client Commands - Experimental/Expansion . . . . . . . . 97 150 6.5.1. X Command . . . . . . . . . . . . . . . . . . . 97 151 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 98 152 7.1. Server Responses - Status Responses . . . . . . . . . . . 99 153 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 107 154 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 108 155 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 108 156 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 108 157 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 109 158 7.2. Server Responses - Server and Mailbox Status . . . . . . 109 159 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 110 160 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 110 161 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 111 162 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 115 163 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 115 164 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 115 165 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 116 166 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 116 167 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 116 168 7.4. Server Responses - Message Status . . . . . . . . . . . . 117 169 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 117 170 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 118 171 7.5. Server Responses - Command Continuation Request . . . . . 124 172 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 124 173 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 125 174 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 143 175 11. Security Considerations . . . . . . . . . . . . . . . . . . . 143 176 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 143 177 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 144 178 11.3. LIST command and Other Users' namespace . . . . . . . . 144 179 11.4. Other Security Considerations . . . . . . . . . . . . . 145 180 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 145 181 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 146 182 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 146 183 12.3. LIST Selection Options, LIST Return Options, LIST 184 extended data items . . . . . . . . . . . . . . . . . . 146 185 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 147 186 13.1. Normative References . . . . . . . . . . . . . . . . . . 147 187 13.2. Informative References (related protocols) . . . . . . . 150 188 13.3. Informative References (historical aspects of IMAP and 189 related protocols) . . . . . . . . . . . . . . . . . . . 152 190 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 152 191 A.1. Mailbox International Naming Convention for compatibility 192 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 153 194 Appendix B. Backward compatibility with BINARY extension . . . . 155 195 Appendix C. Backward compatibility with LIST-EXTENDED extension 155 196 Appendix D. 63 bit body part and message sizes . . . . . . . . . 155 197 Appendix E. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 155 198 Appendix F. Other Recommended IMAP Extensions . . . . . . . . . 157 199 Appendix G. Acknowledgement . . . . . . . . . . . . . . . . . . 157 200 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 201 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 163 203 1. How to Read This Document 205 1.1. Organization of This Document 207 This document is written from the point of view of the implementor of 208 an IMAP4rev2 client or server. Beyond the protocol overview in 209 section 2, it is not optimized for someone trying to understand the 210 operation of the protocol. The material in sections 3 through 5 211 provides the general context and definitions with which IMAP4rev2 212 operates. 214 Sections 6, 7, and 9 describe the IMAP commands, responses, and 215 syntax, respectively. The relationships among these are such that it 216 is almost impossible to understand any of them separately. In 217 particular, do not attempt to deduce command syntax from the command 218 section alone; instead refer to the Formal Syntax section. 220 1.2. Conventions Used in This Document 222 "Conventions" are basic principles or procedures. Document 223 conventions are noted in this section. 225 In examples, "C:" and "S:" indicate lines sent by the client and 226 server respectively. Note that each line includes the terminating 227 CRLF. 229 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 230 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 231 "OPTIONAL" in this document are to be interpreted as described in BCP 232 14 [RFC2119] [RFC8174] when, and only when, they appear in all 233 capitals, as shown here. 235 The word "can" (not "may") is used to refer to a possible 236 circumstance or situation, as opposed to an optional facility of the 237 protocol. 239 "User" is used to refer to a human user, whereas "client" refers to 240 the software being run by the user. 242 "Connection" refers to the entire sequence of client/server 243 interaction from the initial establishment of the network connection 244 until its termination. 246 "Session" refers to the sequence of client/server interaction from 247 the time that a mailbox is selected (SELECT or EXAMINE command) until 248 the time that selection ends (SELECT or EXAMINE of another mailbox, 249 CLOSE command, UNSELECT command, or connection termination). 251 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 252 unless otherwise specified. Other character sets are indicated using 253 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 254 CHARSETs have important additional semantics in addition to defining 255 character set; refer to these documents for more detail. 257 There are several protocol conventions in IMAP. These refer to 258 aspects of the specification which are not strictly part of the IMAP 259 protocol, but reflect generally-accepted practice. Implementations 260 need to be aware of these conventions, and avoid conflicts whether or 261 not they implement the convention. For example, "&" may not be used 262 as a hierarchy delimiter since it conflicts with the Mailbox 263 International Naming Convention, and other uses of "&" in mailbox 264 names are impacted as well. 266 1.3. Special Notes to Implementors 268 Implementors of the IMAP protocol are strongly encouraged to read the 269 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 270 conjunction with this document, to help understand the intricacies of 271 this protocol and how best to build an interoperable product. 273 IMAP4rev2 is designed to be upwards compatible from the IMAP4rev1, 274 the [IMAP2] and unpublished IMAP2bis protocols. IMAP4rev2 is largely 275 compatible with the IMAP4rev1 protocol described in RFC 3501 and the 276 IMAP4 protocol described in RFC 1730; the exception being in certain 277 facilities added in RFC 1730 and RFC 3501 that proved problematic and 278 were subsequently removed or replaced by better alternatives. In the 279 course of the evolution of IMAP4rev2, some aspects in the earlier 280 protocols have become obsolete. Obsolete commands, responses, and 281 data formats which an IMAP4rev2 implementation can encounter when 282 used with an earlier implementation are described in Appendix E, 283 Appendix A and [IMAP-OBSOLETE]. IMAP4rev2 supports 63bit body part 284 and message sizes. IMAP4rev2 compatibility with BINARY and LIST- 285 EXTENDED IMAP extensions are described in Appendix B and Appendix C 286 respectively. 288 Other compatibility issues with IMAP2bis, the most common variant of 289 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 290 discussion of compatibility issues with rare (and presumed extinct) 291 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 292 primarily of historical interest. 294 IMAP was originally developed for the older [RFC-822] standard, and 295 as a consequence several fetch items in IMAP incorporate "RFC822" in 296 their name. In all cases, "RFC822" should be interpreted as a 297 reference to the updated [RFC-5322] standard. 299 2. Protocol Overview 301 2.1. Link Level 303 The IMAP4rev2 protocol assumes a reliable data stream such as that 304 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 305 port 143 or port 993 (IMAP-over-TLS). 307 2.2. Commands and Responses 309 An IMAP4rev2 connection consists of the establishment of a client/ 310 server network connection, an initial greeting from the server, and 311 client/server interactions. These client/server interactions consist 312 of a client command, server data, and a server completion result 313 response. 315 All interactions transmitted by client and server are in the form of 316 lines, that is, strings that end with a CRLF. The protocol receiver 317 of an IMAP4rev2 client or server is either reading a line, or is 318 reading a sequence of octets with a known count followed by a line. 320 2.2.1. Client Protocol Sender and Server Protocol Receiver 322 The client command begins an operation. Each client command is 323 prefixed with an identifier (typically a short alphanumeric string, 324 e.g., A0001, A0002, etc.) called a "tag". A different tag is 325 generated by the client for each command. (More formally: the client 326 SHOULD generate a unique tag for every command, but a server MUST 327 accept tag reuse.) 329 Clients MUST follow the syntax outlined in this specification 330 strictly. It is a syntax error to send a command with missing or 331 extraneous spaces or arguments. 333 There are two cases in which a line from the client does not 334 represent a complete command. In one case, a command argument is 335 quoted with an octet count (see the description of literal in String 336 under Data Formats); in the other case, the command arguments require 337 server feedback (see the AUTHENTICATE command). In either case, the 338 server sends a command continuation request response if it is ready 339 for the octets (if appropriate) and the remainder of the command. 340 This response is prefixed with the token "+". 342 Note: If instead, the server detected an error in the command, it 343 sends a BAD completion response with a tag matching the command 344 (as described below) to reject the command and prevent the client 345 from sending any more of the command. 347 It is also possible for the server to send a completion response 348 for some other command (if multiple commands are in progress), or 349 untagged data. In either case, the command continuation request 350 is still pending; the client takes the appropriate action for the 351 response, and reads another response from the server. In all 352 cases, the client MUST send a complete command (including 353 receiving all command continuation request responses and command 354 continuations for the command) before initiating a new command. 356 The protocol receiver of an IMAP4rev2 server reads a command line 357 from the client, parses the command and its arguments, and transmits 358 server data and a server command completion result response. 360 2.2.2. Server Protocol Sender and Client Protocol Receiver 362 Data transmitted by the server to the client and status responses 363 that do not indicate command completion are prefixed with the token 364 "*", and are called untagged responses. 366 Server data MAY be sent as a result of a client command, or MAY be 367 sent unilaterally by the server. There is no syntactic difference 368 between server data that resulted from a specific command and server 369 data that were sent unilaterally. 371 The server completion result response indicates the success or 372 failure of the operation. It is tagged with the same tag as the 373 client command which began the operation. Thus, if more than one 374 command is in progress, the tag in a server completion response 375 identifies the command to which the response applies. There are 376 three possible server completion responses: OK (indicating success), 377 NO (indicating failure), or BAD (indicating a protocol error such as 378 unrecognized command or command syntax error). 380 Servers SHOULD enforce the syntax outlined in this specification 381 strictly. Any client command with a protocol syntax error, including 382 (but not limited to) missing or extraneous spaces or arguments, 383 SHOULD be rejected, and the client given a BAD server completion 384 response. 386 The protocol receiver of an IMAP4rev2 client reads a response line 387 from the server. It then takes action on the response based upon the 388 first token of the response, which can be a tag, a "*", or a "+". 390 A client MUST be prepared to accept any server response at all times. 391 This includes server data that was not requested. Server data SHOULD 392 be recorded, so that the client can reference its recorded copy 393 rather than sending a command to the server to request the data. In 394 the case of certain server data, the data MUST be recorded. 396 This topic is discussed in greater detail in the Server Responses 397 section. 399 2.3. Message Attributes 401 In addition to message text, each message has several attributes 402 associated with it. These attributes can be retrieved individually 403 or in conjunction with other attributes or message texts. 405 2.3.1. Message Numbers 407 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 408 identifier or the message sequence number. 410 2.3.1.1. Unique Identifier (UID) Message Attribute 412 A UID is an unsigned non-zero 32-bit value assigned to each message, 413 which when used with the unique identifier validity value (see below) 414 forms a 64-bit value that MUST NOT refer to any other message in the 415 mailbox or any subsequent mailbox with the same name forever. Unique 416 identifiers are assigned in a strictly ascending fashion in the 417 mailbox; as each message is added to the mailbox it is assigned a 418 higher UID than the message(s) which were added previously. Unlike 419 message sequence numbers, unique identifiers are not necessarily 420 contiguous. 422 The unique identifier of a message MUST NOT change during the 423 session, and SHOULD NOT change between sessions. Any change of 424 unique identifiers between sessions MUST be detectable using the 425 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 426 are required for a client to resynchronize its state from a previous 427 session with the server (e.g., disconnected or offline access clients 428 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 430 Associated with every mailbox are two 32-bit unsigned non-zero values 431 which aid in unique identifier handling: the next unique identifier 432 value (UIDNEXT) and the unique identifier validity value 433 (UIDVALIDITY). 435 The next unique identifier value is the predicted value that will be 436 assigned to a new message in the mailbox. Unless the unique 437 identifier validity also changes (see below), the next unique 438 identifier value MUST have the following two characteristics. First, 439 the next unique identifier value MUST NOT change unless new messages 440 are added to the mailbox; and second, the next unique identifier 441 value MUST change whenever new messages are added to the mailbox, 442 even if those new messages are subsequently expunged. 444 Note: The next unique identifier value is intended to provide a 445 means for a client to determine whether any messages have been 446 delivered to the mailbox since the previous time it checked this 447 value. It is not intended to provide any guarantee that any 448 message will have this unique identifier. A client can only 449 assume, at the time that it obtains the next unique identifier 450 value, that messages arriving after that time will have a UID 451 greater than or equal to that value. 453 The unique identifier validity value is sent in a UIDVALIDITY 454 response code in an OK untagged response at mailbox selection time. 455 If unique identifiers from an earlier session fail to persist in this 456 session, the unique identifier validity value MUST be greater than 457 the one used in the earlier session. A good UIDVALIDITY value to use 458 is a 32-bit representation of the current date/time when the value is 459 assigned: this ensures that the value is unique and always increases. 460 Another possible alternative is a global counter that gets 461 incremented every time a mailbox is created. 463 Note: Ideally, unique identifiers SHOULD persist at all times. 464 Although this specification recognizes that failure to persist can 465 be unavoidable in certain server environments, it strongly 466 encourages message store implementation techniques that avoid this 467 problem. For example: 469 1. Unique identifiers MUST be strictly ascending in the mailbox 470 at all times. If the physical message store is re-ordered by 471 a non-IMAP agent, this requires that the unique identifiers in 472 the mailbox be regenerated, since the former unique 473 identifiers are no longer strictly ascending as a result of 474 the re-ordering. 476 2. If the message store has no mechanism to store unique 477 identifiers, it must regenerate unique identifiers at each 478 session, and each session must have a unique UIDVALIDITY 479 value. 481 3. If the mailbox is deleted/renamed and a new mailbox with the 482 same name is created at a later date, the server must either 483 keep track of unique identifiers from the previous instance of 484 the mailbox, or it must assign a new UIDVALIDITY value to the 485 new instance of the mailbox. 487 4. The combination of mailbox name, UIDVALIDITY, and UID must 488 refer to a single immutable (or expunged) message on that 489 server forever. In particular, the internal date, [RFC-5322] 490 size, envelope, body structure, and message texts (all 491 BODY[...] fetch data items) must never change. This does not 492 include message numbers, nor does it include attributes that 493 can be set by a STORE command (e.g., FLAGS). When a message 494 is expunged, its UID MUST NOT be reused under the same 495 UIDVALIDITY value. 497 2.3.1.2. Message Sequence Number Message Attribute 499 A Message Sequence Number is a relative position from 1 to the number 500 of messages in the mailbox. This position MUST be ordered by 501 ascending unique identifier. As each new message is added, it is 502 assigned a message sequence number that is 1 higher than the number 503 of messages in the mailbox before that new message was added. 505 Message sequence numbers can be reassigned during the session. For 506 example, when a message is permanently removed (expunged) from the 507 mailbox, the message sequence number for all subsequent messages is 508 decremented. The number of messages in the mailbox is also 509 decremented. Similarly, a new message can be assigned a message 510 sequence number that was once held by some other message prior to an 511 expunge. 513 In addition to accessing messages by relative position in the 514 mailbox, message sequence numbers can be used in mathematical 515 calculations. For example, if an untagged "11 EXISTS" is received, 516 and previously an untagged "8 EXISTS" was received, three new 517 messages have arrived with message sequence numbers of 9, 10, and 11. 518 Another example, if message 287 in a 523 message mailbox has UID 519 12345, there are exactly 286 messages which have lesser UIDs and 236 520 messages which have greater UIDs. 522 2.3.2. Flags Message Attribute 524 A message has associated with it a list of zero or more named tokens, 525 known as "flags". A flag is set by its addition to this list, and is 526 cleared by its removal. There are two types of flags in IMAP4rev2: 527 system flags, and keywords. A flag of either type can also be 528 permanent or session-only. 530 A system flag is a flag name that is pre-defined in this 531 specification and begins with "\". Certain system flags (\Deleted 532 and \Seen) have special semantics described elsewhere in this 533 document. The currently-defined system flags are: 535 \Seen Message has been read 537 \Answered Message has been answered 539 \Flagged Message is "flagged" for urgent/special attention 541 \Deleted Message is "deleted" for removal by later EXPUNGE 543 \Draft Message has not completed composition (marked as a draft). 545 \Recent This flag was in use in IMAP4rev1 and is now deprecated. 547 A keyword is defined by the server implementation. Keywords do not 548 begin with "\". Servers MAY permit the client to define new keywords 549 in the mailbox (see the description of the PERMANENTFLAGS response 550 code for more information). Some keywords that start with "$" are 551 also defined in this specification. 553 This document defines several keywords that were not originally 554 defined in RFC 3501, but which were found to be useful by client 555 implementations. These keywords SHOULD be supported (i.e. allowed in 556 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 557 server implementations: 559 $Forwarded Message has been forwarded to another email address, 560 embedded within or attached to a new message. An email client 561 sets this keyword when it successfully forwards the message to 562 another email address. Typical usage of this keyword is to show a 563 different (or additional) icon for a message that has been 564 forwarded. Once set, the flag SHOULD NOT be cleared. 566 $MDNSent Message Disposition Notification [RFC8098] was generated 567 and sent for this message. See [RFC3503] for more details on how 568 this keyword is used. 570 $Junk The user (or a delivery agent on behalf of the user) may 571 choose to mark a message as definitely containing junk ($Junk; see 572 also the related keyword $NotJunk). The $Junk keyword can be used 573 to mark (and potentially move/delete messages later), group or 574 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 575 information. 577 $NotJunk The user (or a delivery agent on behalf of the user) may 578 choose to mark a message as definitely not containing junk 579 ($NotJunk; see also the related keyword $Junk). The $NotJunk 580 keyword can be used to mark, group or show messages that the user 581 wants to see. See [IMAP-KEYWORDS-REG] for more information. 583 $Phishing The $Phishing keyword can be used by a delivery agent to 584 mark a message as highly likely to be a phishing email. An email 585 that's determined to be a phishing email by the delivery agent 586 should also be considered a junk email and have the appropriate 587 junk filtering applied, including setting the $Junk flag and 588 placing in the \Junk special-use mailbox (see Section 7.2.3) if 589 available. 590 If both the $Phishing flag and the $Junk flag are set, the user 591 agent should display an additional warning message to the user. 592 User agents should not use the term "phishing" in their warning 593 message as most users do not understand this term. Phrasing of 594 the form "this message may be trying to steal your personal 595 information" is recommended. Additionally the user agent may 596 display a warning when clicking on any hyperlinks within the 597 message. 598 The requirement for both $Phishing and $Junk to be set before a 599 user agent displays a warning is for better backwards 600 compatibility with existing clients that understand the $Junk flag 601 but not the $Phishing flag. This so that when an unextended 602 client removes the $Junk flag, an extended client will also show 603 the correct state. See [IMAP-KEYWORDS-REG] for more information. 605 $Junk and $NotJunk are mutually exclusive. If more than one of them 606 is set for a message, the client MUST treat this as if none of them 607 is set and SHOULD unset both of them on the IMAP server. 609 Other registered keywords can be found in the "IMAP and JMAP 610 Keywords" registry [IMAP-KEYWORDS-REG]. New keywords SHOULD be 611 registered in this registry using the procedure specified in 612 [RFC5788]. 614 A flag can be permanent or session-only on a per-flag basis. 615 Permanent flags are those which the client can add or remove from the 616 message flags permanently; that is, concurrent and subsequent 617 sessions will see any change in permanent flags. Changes to session 618 flags are valid only in that session. 620 2.3.3. Internal Date Message Attribute 622 An Internal Date message attribute is the internal date and time of 623 the message on the server. This is not the date and time in the 624 [RFC-5322] header, but rather a date and time which reflects when the 625 message was received. In the case of messages delivered via [SMTP], 626 this is the date and time of final delivery of the message as defined 627 by [SMTP]. In the case of messages delivered by the IMAP4rev2 COPY 628 or MOVE command, this SHOULD be the internal date and time of the 629 source message. In the case of messages delivered by the IMAP4rev2 630 APPEND command, this SHOULD be the date and time as specified in the 631 APPEND command description. All other cases are implementation 632 defined. 634 2.3.4. [RFC-5322] Size Message Attribute 636 An RFC 5322 size is the number of octets in the message, as expressed 637 in [RFC-5322] format. 639 2.3.5. Envelope Structure Message Attribute 641 An Envelope Structure is a parsed representation of the [RFC-5322] 642 header of the message. Note that the IMAP Envelope structure is not 643 the same as an [SMTP] envelope. 645 2.3.6. Body Structure Message Attribute 647 A Body Structure is a parsed representation of the [MIME-IMB] body 648 structure information of the message. 650 2.4. Message Texts 652 In addition to being able to fetch the full [RFC-5322] text of a 653 message, IMAP4rev2 permits the fetching of portions of the full 654 message text. Specifically, it is possible to fetch the [RFC-5322] 655 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 656 [MIME-IMB] header. 658 3. State and Flow Diagram 660 Once the connection between client and server is established, an 661 IMAP4rev2 connection is in one of four states. The initial state is 662 identified in the server greeting. Most commands are only valid in 663 certain states. It is a protocol error for the client to attempt a 664 command while the connection is in an inappropriate state, and the 665 server will respond with a BAD or NO (depending upon server 666 implementation) command completion result. 668 3.1. Not Authenticated State 670 In the not authenticated state, the client MUST supply authentication 671 credentials before most commands will be permitted. This state is 672 entered when a connection starts unless the connection has been pre- 673 authenticated. 675 3.2. Authenticated State 677 In the authenticated state, the client is authenticated and MUST 678 select a mailbox to access before commands that affect messages will 679 be permitted. This state is entered when a pre-authenticated 680 connection starts, when acceptable authentication credentials have 681 been provided, after an error in selecting a mailbox, or after a 682 successful CLOSE command. 684 3.3. Selected State 686 In a selected state, a mailbox has been selected to access. This 687 state is entered when a mailbox has been successfully selected. 689 3.4. Logout State 691 In the logout state, the connection is being terminated. This state 692 can be entered as a result of a client request (via the LOGOUT 693 command) or by unilateral action on the part of either the client or 694 server. 696 If the client requests the logout state, the server MUST send an 697 untagged BYE response and a tagged OK response to the LOGOUT command 698 before the server closes the connection; and the client MUST read the 699 tagged OK response to the LOGOUT command before the client closes the 700 connection. 702 A server SHOULD NOT unilaterally close the connection without sending 703 an untagged BYE response that contains the reason for having done so. 704 A client SHOULD NOT unilaterally close the connection, and instead 705 SHOULD issue a LOGOUT command. If the server detects that the client 706 has unilaterally closed the connection, the server MAY omit the 707 untagged BYE response and simply close its connection. 709 +----------------------+ 710 |connection established| 711 +----------------------+ 712 || 713 \/ 714 +--------------------------------------+ 715 | server greeting | 716 +--------------------------------------+ 717 || (1) || (2) || (3) 718 \/ || || 719 +-----------------+ || || 720 |Not Authenticated| || || 721 +-----------------+ || || 722 || (7) || (4) || || 723 || \/ \/ || 724 || +----------------+ || 725 || | Authenticated |<=++ || 726 || +----------------+ || || 727 || || (7) || (5) || (6) || 728 || || \/ || || 729 || || +--------+ || || 730 || || |Selected|==++ || 731 || || +--------+ || 732 || || || (7) || 733 \/ \/ \/ \/ 734 +--------------------------------------+ 735 | Logout | 736 +--------------------------------------+ 737 || 738 \/ 739 +-------------------------------+ 740 |both sides close the connection| 741 +-------------------------------+ 743 (1) connection without pre-authentication (OK greeting) 744 (2) pre-authenticated connection (PREAUTH greeting) 745 (3) rejected connection (BYE greeting) 746 (4) successful LOGIN or AUTHENTICATE command 747 (5) successful SELECT or EXAMINE command 748 (6) CLOSE command, unsolicited CLOSED response code or 749 failed SELECT or EXAMINE command 750 (7) LOGOUT command, server shutdown, or connection closed 752 4. Data Formats 754 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 755 be in one of several forms: atom, number, string, parenthesized list, 756 or NIL. Note that a particular data item may take more than one 757 form; for example, a data item defined as using "astring" syntax may 758 be either an atom or a string. 760 4.1. Atom 762 An atom consists of one or more non-special characters. 764 4.1.1. Sequence set and UID set 766 A set of messages can be referenced by a sequence set containing 767 either message sequence numbers or unique identifiers. See Section 9 768 for details. Sequence sets can contain ranges (e.g. "5:50"), an 769 enumeration of specific message/UID numbers, a special symbol "*", or 770 a combination of the above. 772 A "UID set" is similar to the sequence set of unique identifiers; 773 however, the "*" value for a sequence number is not permitted. 775 4.2. Number 777 A number consists of one or more digit characters, and represents a 778 numeric value. 780 4.3. String 782 A string is in one of three forms: synchonizing literal, non- 783 synchronizing literal or quoted string. The synchronizing literal 784 form is the general form of string. The non-synchronizing literal 785 form is also the general form, but has length limitation. The quoted 786 string form is an alternative that avoids the overhead of processing 787 a literal at the cost of limitations of characters which may be used. 789 When the distinction between synchronizing and non-synchronizing 790 literals is not important, this document just uses the term 791 "literal". 793 A synchronizing literal is a sequence of zero or more octets 794 (including CR and LF), prefix-quoted with an octet count in the form 795 of an open brace ("{"), the number of octets, close brace ("}"), and 796 CRLF. In the case of synchronizing literals transmitted from server 797 to client, the CRLF is immediately followed by the octet data. In 798 the case of synchronizing literals transmitted from client to server, 799 the client MUST wait to receive a command continuation request 800 (described later in this document) before sending the octet data (and 801 the remainder of the command). 803 The non-synchronizing literal is an alternative form of synchronizing 804 literal, and it may appear in communication from client to server 805 instead of the synchonizing form of literal. The non-synchronizing 806 literal form MUST NOT be sent from server to client. The non- 807 synchronizing literal is distinguished from the synchronizing literal 808 by having a plus ("+") between the octet count and the closing brace 809 ("}"). The server does not generate a command continuation request 810 in response to a non-synchronizing literal, and clients are not 811 required to wait before sending the octets of a non- synchronizing 812 literal. Non-synchronizing literals MUST NOT be larger than 4096 813 octets. Any literal larger than 4096 bytes MUST be sent as a 814 synchronizing literal. (Non-synchronizing literals defined in this 815 document are the same as non-synchronizing literals defined by the 816 LITERAL- extension from [RFC7888]. See that document for details on 817 how to handle invalid non-synchronizing literals longer than 4096 818 octets and for interaction with other IMAP extensions.) 820 A quoted string is a sequence of zero or more Unicode characters, 821 excluding CR and LF, encoded in UTF-8, with double quote (<">) 822 characters at each end. 824 The empty string is represented as "" (a quoted string with zero 825 characters between double quotes), as {0} followed by CRLF (a 826 synchronizing literal with an octet count of 0) or as {0+} followed 827 by CRLF (a non-synchronizing literal with an octet count of 0). 829 Note: Even if the octet count is 0, a client transmitting a 830 synchronizing literal MUST wait to receive a command continuation 831 request. 833 4.3.1. 8-bit and Binary Strings 835 8-bit textual and binary mail is supported through the use of a 836 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 837 transmit 8-bit or multi-octet characters in literals, but SHOULD do 838 so only when the [CHARSET] is identified. 840 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 841 identified charset for header-field values with 8-bit content is 842 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 843 transmit [UTF-8] text in quoted-strings as long as the string does 844 not contain NUL, CR, or LF. This differs from IMAP4rev1 845 implementations. 847 Although a BINARY content transfer encoding is defined, unencoded 848 binary strings are not permitted, unless returned in a in 849 response to BINARY.PEEK[]<> or 850 BINARY[]<> FETCH data item. A "binary 851 string" is any string with NUL characters. A string with an 852 excessive amount of CTL characters MAY also be considered to be 853 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 854 FETCH, client and server implementations MUST encode binary data into 855 a textual form, such as BASE64, before transmitting the data. 857 4.4. Parenthesized List 859 Data structures are represented as a "parenthesized list"; a sequence 860 of data items, delimited by space, and bounded at each end by 861 parentheses. A parenthesized list can contain other parenthesized 862 lists, using multiple levels of parentheses to indicate nesting. 864 The empty list is represented as () -- a parenthesized list with no 865 members. 867 4.5. NIL 869 The special form "NIL" represents the non-existence of a particular 870 data item that is represented as a string or parenthesized list, as 871 distinct from the empty string "" or the empty parenthesized list (). 873 Note: NIL is never used for any data item which takes the form of 874 an atom. For example, a mailbox name of "NIL" is a mailbox named 875 NIL as opposed to a non-existent mailbox name. This is because 876 mailbox uses "astring" syntax which is an atom or a string. 877 Conversely, an addr-name of NIL is a non-existent personal name, 878 because addr-name uses "nstring" syntax which is NIL or a string, 879 but never an atom. 881 Examples: 883 The following LIST response: 885 * LIST () "/" NIL 887 is equivalent to: 888 * LIST () "/" "NIL" 890 as LIST response ABNF is using astring for mailbox name. 892 However, the following response 894 * FETCH 1 (BODY[1] NIL) 896 is not equivalent to: 897 * FETCH 1 (BODY[1] "NIL") 898 The former means absence of the body part, while the latter 899 means that it contains literal sequence of characters "NIL". 901 5. Operational Considerations 903 The following rules are listed here to ensure that all IMAP4rev2 904 implementations interoperate properly. 906 5.1. Mailbox Naming 908 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 909 (this differs from IMAP4rev1). Client implementations MAY attempt to 910 create Net-Unicode mailbox names, and MUST interpret any 8-bit 911 mailbox names returned by LIST as [NET-UNICODE]. Server 912 implementations MUST prohibit the creation of 8-bit mailbox names 913 that do not comply with Net-Unicode. However, servers MAY accept a 914 de-normalized UTF-8 mailbox name and convert it to Unicode 915 normalization form "NFC" (as per Net-Unicode requirements) prior to 916 mailbox creation. Servers that choose to accept such de-normalized 917 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 918 mailbox name parameter. In particular SELECT must open the 919 same mailbox that was successfully created with CREATE , even 920 if is a de-normalized UTF-8 mailbox name. 922 The case-insensitive mailbox name INBOX is a special name reserved to 923 mean "the primary mailbox for this user on this server". (Note that 924 this special name may not exist on some servers for some users, for 925 example if the user has no access to personal namespace.) The 926 interpretation of all other names is implementation-dependent. 928 In particular, this specification takes no position on case 929 sensitivity in non-INBOX mailbox names. Some server implementations 930 are fully case-sensitive in ASCII range; others preserve case of a 931 newly-created name but otherwise are case-insensitive; and yet others 932 coerce names to a particular case. Client implementations must be 933 able to interact with any of these. 935 There are certain client considerations when creating a new mailbox 936 name: 938 1. Any character which is one of the atom-specials (see the Formal 939 Syntax) will require that the mailbox name be represented as a 940 quoted string or literal. 942 2. CTL and other non-graphic characters are difficult to represent 943 in a user interface and are best avoided. Servers MAY refuse to 944 create mailbox names containing Unicode CTL characters. 946 3. Although the list-wildcard characters ("%" and "*") are valid in 947 a mailbox name, it is difficult to use such mailbox names with 948 the LIST command due to the conflict with wildcard 949 interpretation. 951 4. Usually, a character (determined by the server implementation) is 952 reserved to delimit levels of hierarchy. 954 5. Two characters, "#" and "&", have meanings by convention, and 955 should be avoided except when used in that convention. See 956 Section 5.1.2.1 and Appendix A.1 respectively. 958 5.1.1. Mailbox Hierarchy Naming 960 If it is desired to export hierarchical mailbox names, mailbox names 961 MUST be left-to-right hierarchical using a single character to 962 separate levels of hierarchy. The same hierarchy separator character 963 is used for all levels of hierarchy within a single name. 965 5.1.2. Namespaces 967 Personal Namespace: A namespace that the server considers within the 968 personal scope of the authenticated user on a particular connection. 969 Typically, only the authenticated user has access to mailboxes in 970 their Personal Namespace. It is the part of the namespace that 971 belongs to the user that is allocated for mailboxes. If an INBOX 972 exists for a user, it MUST appear within the user's personal 973 namespace. In the typical case, there SHOULD be only one Personal 974 Namespace on a server. 976 Other Users' Namespace: A namespace that consists of mailboxes from 977 the Personal Namespaces of other users. To access mailboxes in the 978 Other Users' Namespace, the currently authenticated user MUST be 979 explicitly granted access rights. For example, it is common for a 980 manager to grant to their secretary access rights to their mailbox. 981 In the typical case, there SHOULD be only one Other Users' Namespace 982 on a server. 984 Shared Namespace: A namespace that consists of mailboxes that are 985 intended to be shared amongst users and do not exist within a user's 986 Personal Namespace. 988 The namespaces a server uses MAY differ on a per-user basis. 990 5.1.2.1. Historic Mailbox Namespace Naming Convention 992 By convention, the first hierarchical element of any mailbox name 993 which begins with "#" identifies the "namespace" of the remainder of 994 the name. This makes it possible to disambiguate between different 995 types of mailbox stores, each of which have their own namespaces. 997 For example, implementations which offer access to USENET 998 newsgroups MAY use the "#news" namespace to partition the USENET 999 newsgroup namespace from that of other mailboxes. Thus, the 1000 comp.mail.misc newsgroup would have a mailbox name of 1001 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 1002 a different object (e.g., a user's private mailbox). 1004 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 1005 friendly requiring the "#" character to be represented as %23 when 1006 within URLs. As such, server implementors MAY instead consider using 1007 namespace prefixes that do not contain the "#" character. 1009 5.1.2.2. Common namespace models 1011 Previous version of this protocol does not define a default server 1012 namespace. Two common namespace models have evolved: 1014 The "Personal Mailbox" model, in which the default namespace that is 1015 presented consists of only the user's personal mailboxes. To access 1016 shared mailboxes, the user must use an escape mechanism to reach 1017 another namespace. 1019 The "Complete Hierarchy" model, in which the default namespace that 1020 is presented includes the user's personal mailboxes along with any 1021 other mailboxes they have access to. 1023 5.2. Mailbox Size and Message Status Updates 1025 At any time, a server can send data that the client did not request. 1026 Sometimes, such behavior is required by this specification and/or 1027 extensions. For example, agents other than the server MAY add 1028 messages to the mailbox (e.g., new message delivery), change the 1029 flags of the messages in the mailbox (e.g., simultaneous access to 1030 the same mailbox by multiple agents), or even remove messages from 1031 the mailbox. A server MUST send mailbox size updates automatically 1032 if a mailbox size change is observed during the processing of a 1033 command. A server SHOULD send message flag updates automatically, 1034 without requiring the client to request such updates explicitly. 1036 Special rules exist for server notification of a client about the 1037 removal of messages to prevent synchronization errors; see the 1038 description of the EXPUNGE response for more detail. In particular, 1039 it is NOT permitted to send an EXISTS response that would reduce the 1040 number of messages in the mailbox; only the EXPUNGE response can do 1041 this. 1043 Regardless of what implementation decisions a client makes on 1044 remembering data from the server, a client implementation MUST record 1045 mailbox size updates. It MUST NOT assume that any command after the 1046 initial mailbox selection will return the size of the mailbox. 1048 5.3. Response when no Command in Progress 1050 Server implementations are permitted to send an untagged response 1051 (except for EXPUNGE) while there is no command in progress. Server 1052 implementations that send such responses MUST deal with flow control 1053 considerations. Specifically, they MUST either (1) verify that the 1054 size of the data does not exceed the underlying transport's available 1055 window size, or (2) use non-blocking writes. 1057 5.4. Autologout Timer 1059 If a server has an inactivity autologout timer that applies to 1060 sessions after authentication, the duration of that timer MUST be at 1061 least 30 minutes. The receipt of any command from the client during 1062 that interval resets the autologout timer. 1064 5.5. Multiple Commands in Progress (Command Pipelining) 1066 The client MAY send another command without waiting for the 1067 completion result response of a command, subject to ambiguity rules 1068 (see below) and flow control constraints on the underlying data 1069 stream. Similarly, a server MAY begin processing another command 1070 before processing the current command to completion, subject to 1071 ambiguity rules. However, any command continuation request responses 1072 and command continuations MUST be negotiated before any subsequent 1073 command is initiated. 1075 The exception is if an ambiguity would result because of a command 1076 that would affect the results of other commands. If the server 1077 detects a possible ambiguity, it MUST execute commands to completion 1078 in the order given by the client. 1080 The most obvious example of ambiguity is when a command would affect 1081 the results of another command, e.g., a FETCH of a message's flags 1082 and a STORE of that same message's flags. 1084 A non-obvious ambiguity occurs with commands that permit an untagged 1085 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1086 since an untagged EXPUNGE response can invalidate sequence numbers in 1087 a subsequent command. This is not a problem for FETCH, STORE, or 1088 SEARCH commands because servers are prohibited from sending EXPUNGE 1089 responses while any of those commands are in progress. Therefore, if 1090 the client sends any command other than FETCH, STORE, or SEARCH, it 1091 MUST wait for the completion result response before sending a command 1092 with message sequence numbers. 1094 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1095 and UID SEARCH are in progress. If the client sends a UID 1096 command, it MUST wait for a completion result response before 1097 sending a command which uses message sequence numbers (this may 1098 include UID SEARCH). Any message sequence numbers in an argument 1099 to UID SEARCH are associated with messages prior to the effect of 1100 any untagged EXPUNGE returned by the UID SEARCH. 1102 For example, the following non-waiting command sequences are invalid: 1104 FETCH + NOOP + STORE 1106 STORE + COPY + FETCH 1108 COPY + COPY 1110 The following are examples of valid non-waiting command sequences: 1112 FETCH + STORE + SEARCH + NOOP 1114 STORE + COPY + EXPUNGE 1116 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1117 command sequence, depending upon whether or not the second UID 1118 SEARCH contains message sequence numbers. 1120 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1121 dependency between two commands. See Section 6.4.4.2 for more 1122 considerations about pipelining such dependent commands. 1124 6. Client Commands 1126 IMAP4rev2 commands are described in this section. Commands are 1127 organized by the state in which the command is permitted. Commands 1128 which are permitted in multiple states are listed in the minimum 1129 permitted state (for example, commands valid in authenticated and 1130 selected state are listed in the authenticated state commands). 1132 Command arguments, identified by "Arguments:" in the command 1133 descriptions below, are described by function, not by syntax. The 1134 precise syntax of command arguments is described in the Formal Syntax 1135 (Section 9). 1137 Some commands cause specific server responses to be returned; these 1138 are identified by "Responses:" in the command descriptions below. 1139 See the response descriptions in the Responses section for 1140 information on these responses, and the Formal Syntax section for the 1141 precise syntax of these responses. It is possible for server data to 1142 be transmitted as a result of any command. Thus, commands that do 1143 not specifically require server data specify "no specific responses 1144 for this command" instead of "none". 1146 The "Result:" in the command description refers to the possible 1147 tagged status responses to a command, and any special interpretation 1148 of these status responses. 1150 The state of a connection is only changed by successful commands 1151 which are documented as changing state. A rejected command (BAD 1152 response) never changes the state of the connection or of the 1153 selected mailbox. A failed command (NO response) generally does not 1154 change the state of the connection or of the selected mailbox; the 1155 exception being the SELECT and EXAMINE commands. 1157 6.1. Client Commands - Any State 1159 The following commands are valid in any state: CAPABILITY, NOOP, and 1160 LOGOUT. 1162 6.1.1. CAPABILITY Command 1164 Arguments: none 1166 Responses: REQUIRED untagged response: CAPABILITY 1167 Result: OK - capability completed 1168 BAD - command unknown or arguments invalid 1170 The CAPABILITY command requests a listing of capabilities that the 1171 server supports. The server MUST send a single untagged CAPABILITY 1172 response with "IMAP4rev2" as one of the listed capabilities before 1173 the (tagged) OK response. 1175 A capability name which begins with "AUTH=" indicates that the server 1176 supports that particular authentication mechanism. All such names 1177 are, by definition, part of this specification. For example, the 1178 authorization capability for an experimental "blurdybloop" 1179 authenticator would be "AUTH=XBLURDYBLOOP" and not 1180 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1182 Other capability names refer to extensions, revisions, or amendments 1183 to this specification. See the documentation of the CAPABILITY 1184 response for additional information. No capabilities, beyond the 1185 base IMAP4rev2 set defined in this specification, are enabled without 1186 explicit client action to invoke the capability. 1188 Client and server implementations MUST implement the STARTTLS, 1189 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1190 See the Security Considerations section for important information. 1192 Unless specified otherwise, all registered extensions to IMAP4rev1 1193 are also valid extensions to IMAP4rev2. 1195 See the section entitled "Client Commands - Experimental/Expansion" 1196 for information about the form of site or implementation-specific 1197 capabilities. 1199 Example: C: abcd CAPABILITY 1200 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1201 LOGINDISABLED 1202 S: abcd OK CAPABILITY completed 1203 C: efgh STARTTLS 1204 S: efgh OK STARTLS completed 1205 1206 C: ijkl CAPABILITY 1207 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1208 S: ijkl OK CAPABILITY completed 1210 6.1.2. NOOP Command 1212 Arguments: none 1214 Responses: no specific responses for this command (but see below) 1215 Result: OK - noop completed 1216 BAD - command unknown or arguments invalid 1218 The NOOP command always succeeds. It does nothing. 1220 Since any command can return a status update as untagged data, the 1221 NOOP command can be used as a periodic poll for new messages or 1222 message status updates during a period of inactivity (the IDLE 1223 command Section 6.3.13 should be used instead of NOOP if real-time 1224 updates to mailbox state are desirable). The NOOP command can also 1225 be used to reset any inactivity autologout timer on the server. 1227 Example: C: a002 NOOP 1228 S: a002 OK NOOP completed 1229 . . . 1230 C: a047 NOOP 1231 S: * 22 EXPUNGE 1232 S: * 23 EXISTS 1233 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1234 S: a047 OK NOOP completed 1236 6.1.3. LOGOUT Command 1238 Arguments: none 1240 Responses: REQUIRED untagged response: BYE 1242 Result: OK - logout completed 1243 BAD - command unknown or arguments invalid 1245 The LOGOUT command informs the server that the client is done with 1246 the connection. The server MUST send a BYE untagged response before 1247 the (tagged) OK response, and then close the network connection. 1249 Example: C: A023 LOGOUT 1250 S: * BYE IMAP4rev2 Server logging out 1251 S: A023 OK LOGOUT completed 1252 (Server and client then close the connection) 1254 6.2. Client Commands - Not Authenticated State 1256 In the not authenticated state, the AUTHENTICATE or LOGIN command 1257 establishes authentication and enters the authenticated state. The 1258 AUTHENTICATE command provides a general mechanism for a variety of 1259 authentication techniques, privacy protection, and integrity 1260 checking; whereas the LOGIN command uses a traditional user name and 1261 plaintext password pair and has no means of establishing privacy 1262 protection or integrity checking. 1264 The STARTTLS command is an alternative form of establishing session 1265 privacy protection and integrity checking, but does not by itself 1266 establish authentication or enter the authenticated state. 1268 Server implementations MAY allow access to certain mailboxes without 1269 establishing authentication. This can be done by means of the 1270 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1271 convention is a LOGIN command using the userid "anonymous"; in this 1272 case, a password is required although the server may choose to accept 1273 any password. The restrictions placed on anonymous users are 1274 implementation-dependent. 1276 Once authenticated (including as anonymous), it is not possible to 1277 re-enter not authenticated state. 1279 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1280 the following commands are valid in the not authenticated state: 1281 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1282 section for important information about these commands. 1284 6.2.1. STARTTLS Command 1286 Arguments: none 1288 Responses: no specific response for this command 1290 Result: OK - starttls completed, begin TLS negotiation 1291 BAD - STARTTLS received after a successful TLS 1292 negotiation or arguments invalid 1294 A TLS [TLS-1.3] negotiation begins immediately after the CRLF at the 1295 end of the tagged OK response from the server. Once a client issues 1296 a STARTTLS command, it MUST NOT issue further commands until a server 1297 response is seen and the TLS negotiation is complete. 1299 The server remains in the non-authenticated state, even if client 1300 credentials are supplied during the TLS negotiation. This does not 1301 preclude an authentication mechanism such as EXTERNAL (defined in 1302 [SASL]) from using client identity determined by the TLS negotiation. 1304 Once TLS has been started, the client MUST discard cached information 1305 about server capabilities and SHOULD re-issue the CAPABILITY command. 1306 This is necessary to protect against man-in- the-middle attacks which 1307 alter the capabilities list prior to STARTTLS. The server MAY 1308 advertise different capabilities, and in particular SHOULD NOT 1309 advertise the STARTTLS capability, after a successful STARTTLS 1310 command. 1312 Example: C: a001 CAPABILITY 1313 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1314 S: a001 OK CAPABILITY completed 1315 C: a002 STARTTLS 1316 S: a002 OK Begin TLS negotiation now 1317 1318 C: a003 CAPABILITY 1319 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1320 S: a003 OK CAPABILITY completed 1321 C: a004 LOGIN joe password 1322 S: a004 OK LOGIN completed 1324 6.2.2. AUTHENTICATE Command 1326 Arguments: SASL authentication mechanism name 1327 OPTIONAL initial response 1329 Responses: continuation data can be requested 1331 Result: OK - authenticate completed, now in authenticated state 1332 NO - authenticate failure: unsupported authentication 1333 mechanism, credentials rejected 1334 BAD - command unknown or arguments invalid, 1335 authentication exchange cancelled 1337 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1338 to the server. If the server supports the requested authentication 1339 mechanism, it performs an authentication protocol exchange to 1340 authenticate and identify the client. It MAY also negotiate an 1341 OPTIONAL security layer for subsequent protocol interactions. If the 1342 requested authentication mechanism is not supported, the server 1343 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1344 response. 1346 The AUTHENTICATE command supports the optional "initial response" 1347 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1348 use it. If a SASL mechanism supports "initial response", but it is 1349 not specified by the client, the server handles this as specified in 1350 Section 3 of [SASL]. 1352 The service name specified by this protocol's profile of [SASL] is 1353 "imap". 1355 The authentication protocol exchange consists of a series of server 1356 challenges and client responses that are specific to the 1357 authentication mechanism. A server challenge consists of a command 1358 continuation request response with the "+" token followed by a BASE64 1359 encoded (see Section 4 of [RFC4648]) string. The client response 1360 consists of a single line consisting of a BASE64 encoded string. If 1361 the client wishes to cancel an authentication exchange, it issues a 1362 line consisting of a single "*". If the server receives such a 1363 response, or if it receives an invalid BASE64 string (e.g. 1364 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1365 reject the AUTHENTICATE command by sending a tagged BAD response. 1367 As with any other client response, this initial response MUST be 1368 encoded as BASE64. It also MUST be transmitted outside of a quoted 1369 string or literal. To send a zero-length initial response, the 1370 client MUST send a single pad character ("="). This indicates that 1371 the response is present, but is a zero-length string. 1373 When decoding the BASE64 data in the initial response, decoding 1374 errors MUST be treated as in any normal SASL client response, i.e. 1375 with a tagged BAD response. In particular, the server should check 1376 for any characters not explicitly allowed by the BASE64 alphabet, as 1377 well as any sequence of BASE64 characters that contains the pad 1378 character ('=') anywhere other than the end of the string (e.g., 1379 "=AAA" and "AAA=BBB" are not allowed). 1381 If the client uses an initial response with a SASL mechanism that 1382 does not support an initial response, the server MUST reject the 1383 command with a tagged BAD response. 1385 If a security layer is negotiated through the [SASL] authentication 1386 exchange, it takes effect immediately following the CRLF that 1387 concludes the authentication exchange for the client, and the CRLF of 1388 the tagged OK response for the server. 1390 While client and server implementations MUST implement the 1391 AUTHENTICATE command itself, it is not required to implement any 1392 authentication mechanisms other than the PLAIN mechanism described in 1393 [PLAIN]. Also, an authentication mechanism is not required to 1394 support any security layers. 1396 Note: a server implementation MUST implement a configuration in 1397 which it does NOT permit any plaintext password mechanisms, unless 1398 either the STARTTLS command has been negotiated or some other 1399 mechanism that protects the session from password snooping has 1400 been provided. Server sites SHOULD NOT use any configuration 1401 which permits a plaintext password mechanism without such a 1402 protection mechanism against password snooping. Client and server 1403 implementations SHOULD implement additional [SASL] mechanisms that 1404 do not use plaintext passwords, such the GSSAPI mechanism 1405 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1406 [SCRAM-SHA-256] mechanisms. 1408 Servers and clients can support multiple authentication mechanisms. 1409 The server SHOULD list its supported authentication mechanisms in the 1410 response to the CAPABILITY command so that the client knows which 1411 authentication mechanisms to use. 1413 A server MAY include a CAPABILITY response code in the tagged OK 1414 response of a successful AUTHENTICATE command in order to send 1415 capabilities automatically. It is unnecessary for a client to send a 1416 separate CAPABILITY command if it recognizes these automatic 1417 capabilities. This should only be done if a security layer was not 1418 negotiated by the AUTHENTICATE command, because the tagged OK 1419 response as part of an AUTHENTICATE command is not protected by 1420 encryption/integrity checking. [SASL] requires the client to re- 1421 issue a CAPABILITY command in this case. The server MAY advertise 1422 different capabilities after a successful AUTHENTICATE command. 1424 If an AUTHENTICATE command fails with a NO response, the client MAY 1425 try another authentication mechanism by issuing another AUTHENTICATE 1426 command. It MAY also attempt to authenticate by using the LOGIN 1427 command (see Section 6.2.3 for more detail). In other words, the 1428 client MAY request authentication types in decreasing order of 1429 preference, with the LOGIN command as a last resort. 1431 The authorization identity passed from the client to the server 1432 during the authentication exchange is interpreted by the server as 1433 the user name whose privileges the client is requesting. 1435 Example: S: * OK IMAP4rev2 Server 1436 C: A001 AUTHENTICATE GSSAPI 1437 S: + 1438 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1439 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1440 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1441 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1442 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1443 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1444 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1445 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1446 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1447 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1448 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1449 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1450 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1451 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1452 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1453 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1454 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1455 C: 1456 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1457 ceP2CWY0SR0fAQAgAAQEBAQ= 1458 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1459 wkhbfa2QteAQAgAG1yYwE= 1460 S: A001 OK GSSAPI authentication successful 1462 Note: The line breaks within server challenges and client responses 1463 are for editorial clarity and are not in real authenticators. 1465 6.2.3. LOGIN Command 1467 Arguments: user name 1468 password 1470 Responses: no specific responses for this command 1472 Result: OK - login completed, now in authenticated state 1473 NO - login failure: user name or password rejected 1474 BAD - command unknown or arguments invalid 1476 The LOGIN command identifies the client to the server and carries the 1477 plaintext password authenticating this user. 1479 A server MAY include a CAPABILITY response code in the tagged OK 1480 response to a successful LOGIN command in order to send capabilities 1481 automatically. It is unnecessary for a client to send a separate 1482 CAPABILITY command if it recognizes these automatic capabilities. 1484 Example: C: a001 LOGIN SMITH SESAME 1485 S: a001 OK LOGIN completed 1487 Note: Use of the LOGIN command over an insecure network (such as the 1488 Internet) is a security risk, because anyone monitoring network 1489 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1490 be used except as a last resort, and it is recommended that client 1491 implementations have a means to disable any automatic use of the 1492 LOGIN command. 1494 Unless either the client is accessing IMAP service on IMAPS port 1495 [RFC8314], the STARTTLS command has been negotiated or some other 1496 mechanism that protects the session from password snooping has been 1497 provided, a server implementation MUST implement a configuration in 1498 which it advertises the LOGINDISABLED capability and does NOT permit 1499 the LOGIN command. Server sites SHOULD NOT use any configuration 1500 which permits the LOGIN command without such a protection mechanism 1501 against password snooping. A client implementation MUST NOT send a 1502 LOGIN command if the LOGINDISABLED capability is advertised. 1504 6.3. Client Commands - Authenticated State 1506 In the authenticated state, commands that manipulate mailboxes as 1507 atomic entities are permitted. Of these commands, the SELECT and 1508 EXAMINE commands will select a mailbox for access and enter the 1509 selected state. 1511 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1512 the following commands are valid in the authenticated state: ENABLE, 1513 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1514 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1516 6.3.1. ENABLE Command 1518 Arguments: capability names 1520 Responses: no specific responses for this command 1522 Result: OK - Relevant capabilities enabled 1523 BAD - No arguments, or syntax error in an argument 1525 Several IMAP extensions allow the server to return unsolicited 1526 responses specific to these extensions in certain circumstances. 1527 However, servers cannot send those unsolicited responses (with the 1528 exception of response codes (see Section 7.1) included in tagged or 1529 untagged OK/NO/BAD responses, which can always be sent) until they 1530 know that the clients support such extensions and thus won't choke on 1531 the extension response data. 1533 The ENABLE command provides an explicit indication from the client 1534 that it supports particular extensions. It is designed such that the 1535 client can send a simple constant string with the extensions it 1536 supports, and the server will enable the shared subset that both 1537 support. 1539 The ENABLE command takes a list of capability names, and requests the 1540 server to enable the named extensions. Once enabled using ENABLE, 1541 each extension remains active until the IMAP connection is closed. 1542 For each argument, the server does the following: 1544 o If the argument is not an extension known to the server, the 1545 server MUST ignore the argument. 1547 o If the argument is an extension known to the server, and it is not 1548 specifically permitted to be enabled using ENABLE, the server MUST 1549 ignore the argument. (Note that knowing about an extension 1550 doesn't necessarily imply supporting that extension.) 1552 o If the argument is an extension that is supported by the server 1553 and that needs to be enabled, the server MUST enable the extension 1554 for the duration of the connection. Note that once an extension 1555 is enabled, there is no way to disable it. 1557 If the ENABLE command is successful, the server MUST send an untagged 1558 ENABLED response Section 7.2.1, which includes all enabled extensions 1559 as specified above. The ENABLED response is sent even if no 1560 extensions were enabled. 1562 Clients SHOULD only include extensions that need to be enabled by the 1563 server. For example, a client can enable IMAP4rev2 specific 1564 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1565 CAPABILITY response. Future RFCs may add to this list. 1567 The ENABLE command is only valid in the authenticated state, before 1568 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1569 SELECT/EXAMINE a mailbox; however, server implementations don't have 1570 to check that no mailbox is selected or was previously selected 1571 during the duration of a connection. 1573 The ENABLE command can be issued multiple times in a session. It is 1574 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1575 single command "ENABLE a b c". When multiple ENABLE commands are 1576 issued, each corresponding ENABLED response SHOULD only contain 1577 extensions enabled by the corresponding ENABLE command, i.e. for the 1578 above example, the ENABLED response to "ENABLE c" should not contain 1579 "a" or "b". 1581 There are no limitations on pipelining ENABLE. For example, it is 1582 possible to send ENABLE and then immediately SELECT, or a LOGIN 1583 immediately followed by ENABLE. 1585 The server MUST NOT change the CAPABILITY list as a result of 1586 executing ENABLE; i.e., a CAPABILITY command issued right after an 1587 ENABLE command MUST list the same capabilities as a CAPABILITY 1588 command issued before the ENABLE command. This is demonstrated in 1589 the following example: 1591 C: t1 CAPABILITY 1592 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1593 S: t1 OK foo 1594 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1595 S: * ENABLED X-GOOD-IDEA 1596 S: t2 OK foo 1597 C: t3 CAPABILITY 1598 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1599 S: t3 OK foo again 1601 In the following example, the client enables CONDSTORE: 1603 C: a1 ENABLE CONDSTORE 1604 S: * ENABLED CONDSTORE 1605 S: a1 OK Conditional Store enabled 1607 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1608 Command 1610 Designers of IMAP extensions are discouraged from creating extensions 1611 that require ENABLE unless there is no good alternative design. 1612 Specifically, extensions that cause potentially incompatible behavior 1613 changes to deployed server responses (and thus benefit from ENABLE) 1614 have a higher complexity cost than extensions that do not. 1616 6.3.2. SELECT Command 1618 Arguments: mailbox name 1620 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1621 REQUIRED OK untagged responses: PERMANENTFLAGS, 1622 UIDNEXT, UIDVALIDITY 1623 REQUIRED untagged response: LIST 1625 Result: OK - select completed, now in selected state 1626 NO - select failure, now in authenticated state: no 1627 such mailbox, can't access mailbox 1628 BAD - command unknown or arguments invalid 1630 The SELECT command selects a mailbox so that messages in the mailbox 1631 can be accessed. Before returning an OK to the client, the server 1632 MUST send the following untagged data to the client. (The order of 1633 individual responses is not important.) Note that earlier versions 1634 of this protocol (e.g. IMAP2bis) only required the FLAGS and EXISTS 1635 untagged data; consequently, client implementations SHOULD implement 1636 default behavior for missing data as discussed with the individual 1637 item. 1639 FLAGS Defined flags in the mailbox. See the description of the 1640 FLAGS response for more detail. 1642 EXISTS The number of messages in the mailbox. See the 1643 description of the EXISTS response for more detail. 1645 LIST The server MUST return a LIST response with the mailbox name. 1646 If the server allows de-normalized UTF-8 mailbox names (see 1647 Section 5.1) and the supplied mailbox name differs from the 1648 normalized version, the server MUST return LIST with the OLDNAME 1649 extended data item. See Section 6.3.9.7 for more details. 1651 OK [PERMANENTFLAGS ()] A list of message flags that 1652 the client can change permanently. If this is missing, the client 1653 should assume that all flags can be changed permanently. 1655 OK [UIDNEXT ] The next unique identifier value. Refer to 1656 Section 2.3.1.1 for more information. 1658 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1659 Section 2.3.1.1 for more information. 1661 Only one mailbox can be selected at a time in a connection; 1662 simultaneous access to multiple mailboxes requires multiple 1663 connections. The SELECT command automatically deselects any 1664 currently selected mailbox before attempting the new selection. 1665 Consequently, if a mailbox is selected and a SELECT command that 1666 fails is attempted, no mailbox is selected. When deselecting a 1667 selected mailbox, the server MUST return an untagged OK response with 1668 the "[CLOSED]" response code when the currently selected mailbox is 1669 closed (see Paragraph 10). 1671 If the client is permitted to modify the mailbox, the server SHOULD 1672 prefix the text of the tagged OK response with the "[READ-WRITE]" 1673 response code. 1675 If the client is not permitted to modify the mailbox but is permitted 1676 read access, the mailbox is selected as read-only, and the server 1677 MUST prefix the text of the tagged OK response to SELECT with the 1678 "[READ-ONLY]" response code. Read-only access through SELECT differs 1679 from the EXAMINE command in that certain read-only mailboxes MAY 1680 permit the change of permanent state on a per-user (as opposed to 1681 global) basis. Netnews messages marked in a server-based .newsrc 1682 file are an example of such per-user permanent state that can be 1683 modified with read-only mailboxes. 1685 Example: C: A142 SELECT INBOX 1686 S: * 172 EXISTS 1687 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1688 S: * OK [UIDNEXT 4392] Predicted next UID 1689 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1690 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1691 S: * LIST () "/" INBOX 1692 S: A142 OK [READ-WRITE] SELECT completed 1694 Example: C: A142 SELECT INBOX 1695 S: * 172 EXISTS 1696 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1697 S: * OK [UIDNEXT 4392] Predicted next UID 1698 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1699 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1700 S: A142 OK [READ-WRITE] SELECT completed 1701 [...some time later...] 1702 C: A143 SELECT Drafts 1703 S: * OK [CLOSED] Previous mailbox is now closed 1704 S: * 5 EXISTS 1705 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1706 S: * OK [UIDNEXT 102] Predicted next UID 1707 S: * LIST () "/" Drafts 1708 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1709 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1710 \Flagged \Draft \*)] System flags and keywords allowed 1711 S: A143 OK [READ-WRITE] SELECT completed 1713 Note that IMAP4rev1 compliant servers can also send the untagged 1714 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1715 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1716 RECENT response. 1718 6.3.3. EXAMINE Command 1720 Arguments: mailbox name 1722 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1723 REQUIRED OK untagged responses: PERMANENTFLAGS, 1724 UIDNEXT, UIDVALIDITY 1725 REQUIRED untagged response: LIST 1727 Result: OK - examine completed, now in selected state 1728 NO - examine failure, now in authenticated state: no 1729 such mailbox, can't access mailbox BAD - command unknown 1730 or arguments invalid 1732 The EXAMINE command is identical to SELECT and returns the same 1733 output; however, the selected mailbox is identified as read-only. No 1734 changes to the permanent state of the mailbox, including per-user 1735 state, are permitted. 1737 The text of the tagged OK response to the EXAMINE command MUST begin 1738 with the "[READ-ONLY]" response code. 1740 Example: C: A932 EXAMINE blurdybloop 1741 S: * 17 EXISTS 1742 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1743 S: * OK [UIDNEXT 4392] Predicted next UID 1744 S: * LIST () "/" blurdybloop 1745 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1746 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1747 S: A932 OK [READ-ONLY] EXAMINE completed 1749 6.3.4. CREATE Command 1751 Arguments: mailbox name 1753 Responses: OPTIONAL untagged response: LIST 1755 Result: OK - create completed 1756 NO - create failure: can't create mailbox with that name 1757 BAD - command unknown or arguments invalid 1759 The CREATE command creates a mailbox with the given name. An OK 1760 response is returned only if a new mailbox with that name has been 1761 created. It is an error to attempt to create INBOX or a mailbox with 1762 a name that refers to an extant mailbox. Any error in creation will 1763 return a tagged NO response. If a client attempts to create a UTF-8 1764 mailbox name that is not a valid Net-Unicode name, the server MUST 1765 reject the creation or convert the name to Net-Unicode prior to 1766 creating the mailbox. If the server decides to convert (normalize) 1767 the name, it SHOULD return an untagged LIST with OLDNAME extended 1768 data item, with the OLDNAME value being the supplied mailbox name and 1769 the name parameter being the normalized mailbox name. (See 1770 Section 6.3.9.7 for more details.) 1772 Mailboxes created in one IMAP session MAY be announced to other IMAP 1773 sessions using unsolicited LIST response. If the server 1774 automatically subscribes a mailbox when it is created, then the 1775 unsolicited LIST response for each affected subscribed mailbox name 1776 MUST include the \Subscribed attribute. 1778 If the mailbox name is suffixed with the server's hierarchy separator 1779 character (as returned from the server by a LIST command), this is a 1780 declaration that the client intends to create mailbox names under 1781 this name in the hierarchy. Server implementations that do not 1782 require this declaration MUST ignore the declaration. In any case, 1783 the name created is without the trailing hierarchy delimiter. 1785 If the server's hierarchy separator character appears elsewhere in 1786 the name, the server SHOULD create any superior hierarchical names 1787 that are needed for the CREATE command to be successfully completed. 1788 In other words, an attempt to create "foo/bar/zap" on a server in 1789 which "/" is the hierarchy separator character SHOULD create foo/ and 1790 foo/bar/ if they do not already exist. 1792 If a new mailbox is created with the same name as a mailbox which was 1793 deleted, its unique identifiers MUST be greater than any unique 1794 identifiers used in the previous incarnation of the mailbox unless 1795 the new incarnation has a different unique identifier validity value. 1796 See the description of the UID command for more detail. 1798 Example: C: A003 CREATE owatagusiam/ 1799 S: A003 OK CREATE completed 1800 C: A004 CREATE owatagusiam/blurdybloop 1801 S: A004 OK CREATE completed 1802 C: A005 CREATE NonNormalized 1803 S: * LIST () "/" "Normalized" ("OLDNAME" ("NonNormalized")) 1804 S: A005 OK CREATE completed 1806 (in the last example imagine that "NonNormalized" is 1807 a non NFC normalized Unicode mailbox name and that 1808 "Normalized" is its NFC normalized version.) 1810 Note: The interpretation of this example depends on whether "/" 1811 was returned as the hierarchy separator from LIST. If "/" is the 1812 hierarchy separator, a new level of hierarchy named "owatagusiam" 1813 with a member called "blurdybloop" is created. Otherwise, two 1814 mailboxes at the same hierarchy level are created. 1816 6.3.5. DELETE Command 1818 Arguments: mailbox name 1820 Responses: OPTIONAL untagged response: LIST 1822 Result: OK - delete completed 1823 NO - delete failure: can't delete mailbox with that name 1824 BAD - command unknown or arguments invalid 1826 The DELETE command permanently removes the mailbox with the given 1827 name. A tagged OK response is returned only if the mailbox has been 1828 deleted. It is an error to attempt to delete INBOX or a mailbox name 1829 that does not exist. 1831 The DELETE command MUST NOT remove inferior hierarchical names. For 1832 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1833 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1834 "foo.bar". It is an error to attempt to delete a name that has 1835 inferior hierarchical names and also has the \Noselect mailbox name 1836 attribute (see the description of the LIST response for more 1837 details). 1839 It is permitted to delete a name that has inferior hierarchical names 1840 and does not have the \Noselect mailbox name attribute. If the 1841 server implementation does not permit deleting the name while 1842 inferior hierarchical names exists then it SHOULD disallow the DELETE 1843 command by returning a tagged NO response. The NO response SHOULD 1844 include the HASCHILDREN response code. Alternatively the server MAY 1845 allow the DELETE command, but sets the \Noselect mailbox name 1846 attribute for that name. 1848 If the server returns OK response, all messages in that mailbox are 1849 removed by the DELETE command. 1851 The value of the highest-used unique identifier of the deleted 1852 mailbox MUST be preserved so that a new mailbox created with the same 1853 name will not reuse the identifiers of the former incarnation, unless 1854 the new incarnation has a different unique identifier validity value. 1855 See the description of the UID command for more detail. 1857 If the server decides to convert (normalize) the mailbox name, it 1858 SHOULD return an untagged LIST with the "\NonExistent" attribute and 1859 OLDNAME extended data item, with the OLDNAME value being the supplied 1860 mailbox name and the name parameter being the normalized mailbox 1861 name. (See Section 6.3.9.7 for more details.) 1863 Mailboxes deleted in one IMAP session MAY be announced to other IMAP 1864 sessions using unsolicited LIST response, containing the 1865 "\NonExistent" attribute. 1867 Examples: C: A682 LIST "" * 1868 S: * LIST () "/" blurdybloop 1869 S: * LIST (\Noselect) "/" foo 1870 S: * LIST () "/" foo/bar 1871 S: A682 OK LIST completed 1872 C: A683 DELETE blurdybloop 1873 S: A683 OK DELETE completed 1874 C: A684 DELETE foo 1875 S: A684 NO Name "foo" has inferior hierarchical names 1876 C: A685 DELETE foo/bar 1877 S: A685 OK DELETE Completed 1878 C: A686 LIST "" * 1879 S: * LIST (\Noselect) "/" foo 1880 S: A686 OK LIST completed 1881 C: A687 DELETE foo 1882 S: A687 OK DELETE Completed 1883 C: A82 LIST "" * 1884 S: * LIST () "." blurdybloop 1885 S: * LIST () "." foo 1886 S: * LIST () "." foo.bar 1887 S: A82 OK LIST completed 1888 C: A83 DELETE blurdybloop 1889 S: A83 OK DELETE completed 1890 C: A84 DELETE foo 1891 S: A84 OK DELETE Completed 1892 C: A85 LIST "" * 1893 S: * LIST () "." foo.bar 1894 S: A85 OK LIST completed 1895 C: A86 LIST "" % 1896 S: * LIST (\Noselect) "." foo 1897 S: A86 OK LIST completed 1899 6.3.6. RENAME Command 1901 Arguments: existing mailbox name 1902 new mailbox name 1904 Responses: OPTIONAL untagged response: LIST 1906 Result: OK - rename completed 1907 NO - rename failure: can't rename mailbox with that name, 1908 can't rename to mailbox with that name 1909 BAD - command unknown or arguments invalid 1911 The RENAME command changes the name of a mailbox. A tagged OK 1912 response is returned only if the mailbox has been renamed. It is an 1913 error to attempt to rename from a mailbox name that does not exist or 1914 to a mailbox name that already exists. Any error in renaming will 1915 return a tagged NO response. 1917 If the name has inferior hierarchical names, then the inferior 1918 hierarchical names MUST also be renamed. For example, a rename of 1919 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1920 delimiter character) to "zap/bar". 1922 If the server's hierarchy separator character appears in the name, 1923 the server SHOULD create any superior hierarchical names that are 1924 needed for the RENAME command to complete successfully. In other 1925 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1926 server in which "/" is the hierarchy separator character in the 1927 corresponding namespace SHOULD create baz/ and baz/rag/ if they do 1928 not already exist. 1930 The value of the highest-used unique identifier of the old mailbox 1931 name MUST be preserved so that a new mailbox created with the same 1932 name will not reuse the identifiers of the former incarnation, unless 1933 the new incarnation has a different unique identifier validity value. 1934 See the description of the UID command for more detail. 1936 Renaming INBOX is permitted (i.e. it doesn't result in a tagged BAD 1937 response), and has special behavior. (Note that some servers 1938 disallow renaming INBOX by returning a tagged NO response, so clients 1939 need to be able to handle such RENAME failing). It moves all 1940 messages in INBOX to a new mailbox with the given name, leaving INBOX 1941 empty. If the server implementation supports inferior hierarchical 1942 names of INBOX, these are unaffected by a rename of INBOX. 1944 If the server allows creation of mailboxes with names that are not 1945 valid Net-Unicode names, the server normalizes both the existing 1946 mailbox name parameter and the new mailbox name parameter. If the 1947 normalized version of any of these 2 parameters differs from the 1948 corresponding supplied version, the server SHOULD return an untagged 1949 LIST response with OLDNAME extended data item, with the OLDNAME value 1950 being the supplied existing mailbox name and the name parameter being 1951 the normalized new mailbox name (see Section 6.3.9.7). This would 1952 allow the client to correlate supplied name with the normalized name. 1954 Mailboxes renamed in one IMAP session MAY be announced to other IMAP 1955 sessions using unsolicited LIST response with OLDNAME extended data 1956 item. 1958 In both of the above cases: if the server automatically subscribes a 1959 mailbox when it is renamed, then the unsolicited LIST response for 1960 each affected subscribed mailbox name MUST include the \Subscribed 1961 attribute. No unsolicited LIST responses need to be sent for 1962 children mailboxes, if any. When INBOX is successfully renamed, a 1963 new INBOX is assumed to be created. No unsolicited LIST responses 1964 need to be sent for INBOX in this case. 1966 Examples: C: A682 LIST "" * 1967 S: * LIST () "/" blurdybloop 1968 S: * LIST (\Noselect) "/" foo 1969 S: * LIST () "/" foo/bar 1970 S: A682 OK LIST completed 1971 C: A683 RENAME blurdybloop sarasoop 1972 S: A683 OK RENAME completed 1973 C: A684 RENAME foo zowie 1974 S: A684 OK RENAME Completed 1975 C: A685 LIST "" * 1976 S: * LIST () "/" sarasoop 1977 S: * LIST (\Noselect) "/" zowie 1978 S: * LIST () "/" zowie/bar 1979 S: A685 OK LIST completed 1981 C: Z432 LIST "" * 1982 S: * LIST () "." INBOX 1983 S: * LIST () "." INBOX.bar 1984 S: Z432 OK LIST completed 1985 C: Z433 RENAME INBOX old-mail 1986 S: Z433 OK RENAME completed 1987 C: Z434 LIST "" * 1988 S: * LIST () "." INBOX 1989 S: * LIST () "." INBOX.bar 1990 S: * LIST () "." old-mail 1991 S: Z434 OK LIST completed 1993 Note that renaming a mailbox doesn't update subscription information 1994 on the original name. To keep subscription information in sync, the 1995 following sequence of commands can be used: 1997 C: 1001 RENAME X Y 1998 C: 1002 SUBSCRIBE Y 1999 C: 1003 UNSUBSCRIBE X 2001 Note that the above sequence of commands doesn't account for updating 2002 subscription for any children mailboxes of mailbox X. 2004 6.3.7. SUBSCRIBE Command 2006 Arguments: mailbox 2008 Responses: no specific responses for this command 2009 Result: OK - subscribe completed 2010 NO - subscribe failure: can't subscribe to that name 2011 BAD - command unknown or arguments invalid 2013 The SUBSCRIBE command adds the specified mailbox name to the server's 2014 set of "active" or "subscribed" mailboxes as returned by the LIST 2015 (SUBSCRIBED) command. This command returns a tagged OK response if 2016 the subscription is successful or if the mailbox is already 2017 subscribed. 2019 A server MAY validate the mailbox argument to SUBSCRIBE to verify 2020 that it exists. However, it SHOULD NOT unilaterally remove an 2021 existing mailbox name from the subscription list even if a mailbox by 2022 that name no longer exists. 2024 Note: This requirement is because a server site can choose to 2025 routinely remove a mailbox with a well-known name (e.g., "system- 2026 alerts") after its contents expire, with the intention of 2027 recreating it when new contents are appropriate. 2029 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 2030 S: A002 OK SUBSCRIBE completed 2032 6.3.8. UNSUBSCRIBE Command 2034 Arguments: mailbox name 2036 Responses: no specific responses for this command 2038 Result: OK - unsubscribe completed 2039 NO - unsubscribe failure: can't unsubscribe that name 2040 BAD - command unknown or arguments invalid 2042 The UNSUBSCRIBE command removes the specified mailbox name from the 2043 server's set of "active" or "subscribed" mailboxes as returned by the 2044 LIST (SUBSCRIBED) command. This command returns a tagged OK response 2045 if the unsubscription is successful or if the mailbox is not 2046 subscribed. 2048 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 2049 S: A002 OK UNSUBSCRIBE completed 2051 6.3.9. LIST Command 2053 Arguments (basic): reference name 2054 mailbox name with possible wildcards 2056 Arguments (extended): selection options (OPTIONAL) 2057 reference name 2058 mailbox patterns 2059 return options (OPTIONAL) 2061 Responses: untagged responses: LIST 2063 Result: OK - list completed 2064 NO - list failure: can't list that reference or mailbox 2065 name 2066 BAD - command unknown or arguments invalid 2068 The LIST command returns a subset of mailbox names from the complete 2069 set of all mailbox names available to the client. Zero or more 2070 untagged LIST replies are returned, containing the name attributes, 2071 hierarchy delimiter, name, and possible extension information; see 2072 the description of the LIST reply for more detail. 2074 The LIST command SHOULD return its data quickly, without undue delay. 2075 For example, it SHOULD NOT go to excess trouble to calculate the 2076 \Marked or \Unmarked status or perform other processing; if each name 2077 requires 1 second of processing, then a list of 1200 names would take 2078 20 minutes! 2080 The extended LIST command, originally introduced in [RFC5258], 2081 provides capabilities beyond that of the original IMAP LIST command. 2082 The extended syntax is being used if one or more of the following 2083 conditions is true: 2085 1. if the first word after the command name begins with a 2086 parenthesis ("LIST selection options"); 2088 2. if the second word after the command name begins with a 2089 parenthesis; 2091 3. if the LIST command has more than 2 parameters ("LIST return 2092 options") 2094 An empty ("" string) reference name argument indicates that the 2095 mailbox name is interpreted as by SELECT. The returned mailbox names 2096 MUST match the supplied mailbox name pattern(s). A non-empty 2097 reference name argument is the name of a mailbox or a level of 2098 mailbox hierarchy, and indicates the context in which the mailbox 2099 name is interpreted. Clients SHOULD use the empty reference 2100 argument. 2102 In the basic syntax only, an empty ("" string) mailbox name argument 2103 is a special request to return the hierarchy delimiter and the root 2104 name of the name given in the reference. The value returned as the 2105 root MAY be the empty string if the reference is non-rooted or is an 2106 empty string. In all cases, a hierarchy delimiter (or NIL if there 2107 is no hierarchy) is returned. This permits a client to get the 2108 hierarchy delimiter (or find out that the mailbox names are flat) 2109 even when no mailboxes by that name currently exist. 2111 In the extended syntax, any mailbox name arguments that are empty 2112 strings are ignored. There is no special meaning for empty mailbox 2113 names when the extended syntax is used. 2115 The reference and mailbox name arguments are interpreted into a 2116 canonical form that represents an unambiguous left-to-right 2117 hierarchy. The returned mailbox names will be in the interpreted 2118 form, that we call "canonical LIST pattern" later in this document. 2119 To define the term "canonical LIST pattern" formally: it refers to 2120 the canonical pattern constructed internally by the server from the 2121 reference and mailbox name arguments. 2123 Note: The interpretation of the reference argument is 2124 implementation-defined. It depends upon whether the server 2125 implementation has a concept of the "current working directory" 2126 and leading "break out characters", which override the current 2127 working directory. 2129 For example, on a server which exports a UNIX or NT filesystem, 2130 the reference argument contains the current working directory, and 2131 the mailbox name argument would contain the name as interpreted in 2132 the current working directory. 2134 If a server implementation has no concept of break out characters, 2135 the canonical form is normally the reference name appended with 2136 the mailbox name. Note that if the server implements the 2137 namespace convention (Section 5.1.2.1), "#" is a break out 2138 character and must be treated as such. 2140 If the reference argument is not a level of mailbox hierarchy 2141 (that is, it is a \NoInferiors name), and/or the reference 2142 argument does not end with the hierarchy delimiter, it is 2143 implementation-dependent how this is interpreted. For example, a 2144 reference of "foo/bar" and mailbox name of "rag/baz" could be 2145 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2146 baz". A client SHOULD NOT use such a reference argument except at 2147 the explicit request of the user. A hierarchical browser MUST NOT 2148 make any assumptions about server interpretation of the reference 2149 unless the reference is a level of mailbox hierarchy AND ends with 2150 the hierarchy delimiter. 2152 Any part of the reference argument that is included in the 2153 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2154 be in the same form as the reference name argument. This rule 2155 permits the client to determine if the returned mailbox name is in 2156 the context of the reference argument, or if something about the 2157 mailbox argument overrode the reference argument. Without this rule, 2158 the client would have to have knowledge of the server's naming 2159 semantics including what characters are "breakouts" that override a 2160 naming context. 2162 Here are some examples of how references 2163 and mailbox names might be interpreted on a UNIX-based 2164 server: 2166 Reference Mailbox Name Interpretation 2167 ------------ ------------ -------------- 2168 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2169 archive/ % archive/% 2170 #news. comp.mail.* #news.comp.mail.* 2171 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2172 archive/ ~fred/Mail/* ~fred/Mail/* 2174 The first three examples demonstrate interpretations in 2175 the context of the reference argument. Note that 2176 "~smith/Mail" SHOULD NOT be transformed into something 2177 like "/u2/users/smith/Mail", or it would be impossible 2178 for the client to determine that the interpretation was 2179 in the context of the reference. 2181 The character "*" is a wildcard, and matches zero or more characters 2182 at this position. The character "%" is similar to "*", but it does 2183 not match a hierarchy delimiter. If the "%" wildcard is the last 2184 character of a mailbox name argument, matching levels of hierarchy 2185 are also returned. If these levels of hierarchy are not also 2186 selectable mailboxes, they are returned with the \Noselect mailbox 2187 name attribute (see the description of the LIST response for more 2188 details). 2190 Any syntactically valid pattern that is not accepted by a server for 2191 any reason MUST be silently ignored. I.e. it results in no LIST 2192 responses and the LIST command still returns tagged OK response. 2194 Selection options tell the server to limit the mailbox names that are 2195 selected by the LIST operation. If selection options are used, the 2196 mailboxes returned are those that match both the list of canonical 2197 LIST patterns and the selection options. Unless a particular 2198 selection option provides special rules, the selection options are 2199 cumulative: a mailbox that matches the mailbox patterns is selected 2200 only if it also matches all of the selection options. (An example of 2201 a selection option with special rules is the RECURSIVEMATCH option.) 2203 Return options control what information is returned for each matched 2204 mailbox. Return options MUST NOT cause the server to report 2205 information about additional mailbox names other than those that 2206 match the canonical LIST patterns and selection options. If no 2207 return options are specified, the client is only expecting 2208 information about mailbox attributes. The server MAY return other 2209 information about the matched mailboxes, and clients MUST be able to 2210 handle that situation. 2212 Initial selection options and return options are defined in the 2213 following subsections, and new ones will also be defined in 2214 extensions. Initial options defined in this document MUST be 2215 supported. Each non-initial option will be enabled by a capability 2216 string (one capability may enable multiple options), and a client 2217 MUST NOT send an option for which the server has not advertised 2218 support. A server MUST respond to options it does not recognize with 2219 a BAD response. The client SHOULD NOT specify any option more than 2220 once; however, if the client does this, the server MUST act as if it 2221 received the option only once. The order in which options are 2222 specified by the client is not significant. 2224 In general, each selection option except RECURSIVEMATCH will have a 2225 corresponding return option with the same name. The REMOTE selection 2226 option is an anomaly in this regard, and does not have a 2227 corresponding return option. That is because it expands, rather than 2228 restricts, the set of mailboxes that are returned. Future extensions 2229 to this specification should keep this parallelism in mind and define 2230 a pair of corresponding selection and return options. 2232 Server implementations are permitted to "hide" otherwise accessible 2233 mailboxes from the wildcard characters, by preventing certain 2234 characters or names from matching a wildcard in certain situations. 2235 For example, a UNIX-based server might restrict the interpretation of 2236 "*" so that an initial "/" character does not match. 2238 The special name INBOX is included in the output from LIST, if INBOX 2239 is supported by this server for this user and if the uppercase string 2240 "INBOX" matches the interpreted reference and mailbox name arguments 2241 with wildcards as described above. The criteria for omitting INBOX 2242 is whether SELECT INBOX will return failure; it is not relevant 2243 whether the user's real INBOX resides on this or some other server. 2245 6.3.9.1. LIST Selection Options 2247 The selection options defined in this specification are as follows: 2249 SUBSCRIBED - causes the LIST command to list subscribed names, 2250 rather than the existing mailboxes. This will often be a subset 2251 of the actual mailboxes. It's also possible for this list to 2252 contain the names of mailboxes that don't exist. In any case, the 2253 list MUST include exactly those mailbox names that match the 2254 canonical list pattern and are subscribed to. 2256 This option defines a mailbox attribute, "\Subscribed", that 2257 indicates that a mailbox name is subscribed to. The "\Subscribed" 2258 attribute MUST be supported and MUST be accurately computed when 2259 the SUBSCRIBED selection option is specified. 2261 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2262 return option (see below). 2264 REMOTE - causes the LIST command to show remote mailboxes as well as 2265 local ones, as described in [RFC2193]. This option is intended to 2266 replace the RLIST command and, in conjunction with the SUBSCRIBED 2267 selection option, the RLSUB command. Servers that don't support 2268 remote mailboxes just ignore this option. 2270 This option defines a mailbox attribute, "\Remote", that indicates 2271 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2272 be accurately computed when the REMOTE option is specified. 2274 The REMOTE selection option has no interaction with other options. 2275 Its effect is to tell the server to apply the other options, if 2276 any, to remote mailboxes, in addition to local ones. In 2277 particular, it has no interaction with RECURSIVEMATCH (see below). 2278 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2279 request for (RECURSIVEMATCH) is also invalid. A request for 2280 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2281 mailboxes, both local and remote. 2283 RECURSIVEMATCH - this option forces the server to return information 2284 about parent mailboxes that don't match other selection options, 2285 but have some submailboxes that do. Information about children is 2286 returned in the CHILDINFO extended data item, as described in 2287 Section 6.3.9.6. 2289 Note 1: In order for a parent mailbox to be returned, it still has 2290 to match the canonical LIST pattern. 2292 Note 2: When returning the CHILDINFO extended data item, it 2293 doesn't matter whether or not the submailbox matches the canonical 2294 LIST pattern. See also example 9 in Section 6.3.9.8. 2296 The RECURSIVEMATCH option MUST NOT occur as the only selection 2297 option (or only with REMOTE), as it only makes sense when other 2298 selection options are also used. The server MUST return BAD 2299 tagged response in such case. 2301 Note that even if the RECURSIVEMATCH option is specified, the 2302 client MUST still be able to handle a case when a CHILDINFO 2303 extended data item is returned and there are no submailboxes that 2304 meet the selection criteria of the subsequent LIST command, as 2305 they can be deleted/renamed after the LIST response was sent, but 2306 before the client had a chance to access them. 2308 6.3.9.2. LIST Return Options 2310 The return options defined in this specification are as follows: 2312 SUBSCRIBED - causes the LIST command to return subscription state 2313 for all matching mailbox names. The "\Subscribed" attribute MUST 2314 be supported and MUST be accurately computed when the SUBSCRIBED 2315 return option is specified. Further, all mailbox flags MUST be 2316 accurately computed (this differs from the behavior of the 2317 obsolete LSUB command from IMAP4rev1). 2319 CHILDREN - requests mailbox child information as originally proposed 2320 in [RFC3348]. See Section 6.3.9.5, below, for details. This 2321 option MUST be supported by all servers. 2323 STATUS - requests STATUS response for each matching mailbox. 2325 This option takes STATUS data items as parameters. For each 2326 selectable mailbox matching the list pattern and selection 2327 options, the server MUST return an untagged LIST response 2328 followed by an untagged STATUS response containing the 2329 information requested in the STATUS return option, except for 2330 some cases described below. 2332 If an attempted STATUS for a listed mailbox fails because the 2333 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2334 is granted to the mailbox and the "r" right is not granted, or 2335 due to a race condition between LIST and STATUS changing the 2336 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2337 and the LIST response MUST include the \NoSelect attribute. 2339 This means the server may have to buffer the LIST reply until 2340 it has successfully looked up the necessary STATUS information. 2342 If the server runs into unexpected problems while trying to 2343 look up the STATUS information, it MAY drop the corresponding 2344 STATUS reply. In such a situation, the LIST command would 2345 still return a tagged OK reply. 2347 6.3.9.3. General Principles for Returning LIST Responses 2349 This section outlines several principles that can be used by server 2350 implementations of this document to decide whether a LIST response 2351 should be returned, as well as how many responses and what kind of 2352 information they may contain. 2354 1. At most one LIST response should be returned for each mailbox 2355 name that matches the canonical LIST pattern. Server 2356 implementors must not assume that clients will be able to 2357 assemble mailbox attributes and other information returned in 2358 multiple LIST responses. 2360 2. There are only two reasons for including a matching mailbox name 2361 in the responses to the LIST command (note that the server is 2362 allowed to return unsolicited responses at any time, and such 2363 responses are not governed by this rule): 2365 A. The mailbox name also satisfies the selection criteria. 2367 B. The mailbox name doesn't satisfy the selection criteria, but 2368 it has at least one descendant mailbox name that satisfies 2369 the selection criteria and that doesn't match the canonical 2370 LIST pattern. 2372 For more information on this case, see the CHILDINFO extended 2373 data item described in Section 6.3.9.6. Note that the 2374 CHILDINFO extended data item can only be returned when the 2375 RECURSIVEMATCH selection option is specified. 2377 3. Attributes returned in the same LIST response must be treated 2378 additively. For example, the following response 2380 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2382 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2383 subscribed. 2385 6.3.9.4. Additional LIST-related Requirements on Clients 2387 All clients MUST treat a LIST attribute with a stronger meaning as 2388 implying any attribute that can be inferred from it. (See 2389 Section 7.2.3 for the list of currently defined attributes). For 2390 example, the client must treat the presence of the \NoInferiors 2391 attribute as if the \HasNoChildren attribute was also sent by the 2392 server. 2394 The following table summarizes inference rules. 2396 +--------------------+-------------------+ 2397 | returned attribute | implied attribute | 2398 +--------------------+-------------------+ 2399 | \NoInferiors | \HasNoChildren | 2400 | \NonExistent | \NoSelect | 2401 +--------------------+-------------------+ 2403 6.3.9.5. The CHILDREN Return Option 2405 The CHILDREN return option is simply an indication that the client 2406 wants information about whether or not mailboxes contain children 2407 mailboxes; a server MAY provide it even if the option is not 2408 specified. 2410 Many IMAP4 clients present to the user a hierarchical view of the 2411 mailboxes that a user has access to. Rather than initially 2412 presenting to the user the entire mailbox hierarchy, it is often 2413 preferable to show to the user a collapsed outline list of the 2414 mailbox hierarchy (particularly if there is a large number of 2415 mailboxes). The user can then expand the collapsed outline hierarchy 2416 as needed. It is common to include within the collapsed hierarchy a 2417 visual clue (such as a ''+'') to indicate that there are child 2418 mailboxes under a particular mailbox. When the visual clue is 2419 clicked, the hierarchy list is expanded to show the child mailboxes. 2420 The CHILDREN return option provides a mechanism for a client to 2421 efficiently determine whether a particular mailbox has children, 2422 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2423 The CHILDREN return option defines two new attributes that MUST be 2424 returned within a LIST response: \HasChildren and \HasNoChildren. 2425 Although these attributes MAY be returned in response to any LIST 2426 command, the CHILDREN return option is provided to indicate that the 2427 client particularly wants this information. If the CHILDREN return 2428 option is present, the server MUST return these attributes even if 2429 their computation is expensive. 2431 \HasChildren 2432 The presence of this attribute indicates that the mailbox has 2433 child mailboxes. A server SHOULD NOT set this attribute if 2434 there are child mailboxes and the user does not have permission 2435 to access any of them. In this case, \HasNoChildren SHOULD be 2436 used. In many cases, however, a server may not be able to 2437 efficiently compute whether a user has access to any child 2438 mailbox. Note that even though the \HasChildren attribute for a 2439 mailbox must be correct at the time of processing of the 2440 mailbox, a client must be prepared to deal with a situation when 2441 a mailbox is marked with the \HasChildren attribute, but no 2442 child mailbox appears in the response to the LIST command. This 2443 might happen, for example, due to children mailboxes being 2444 deleted or made inaccessible to the user (using access control) 2445 by another client before the server is able to list them. 2447 \HasNoChildren 2449 The presence of this attribute indicates that the mailbox has NO 2450 child mailboxes that are accessible to the currently 2451 authenticated user. 2453 It is an error for the server to return both a \HasChildren and a 2454 \HasNoChildren attribute in the same LIST response. 2456 Note: the \HasNoChildren attribute should not be confused with the 2457 the \NoInferiors attribute, which indicates that no child mailboxes 2458 exist now and none can be created in the future. 2460 6.3.9.6. CHILDINFO Extended Data Item 2462 The CHILDINFO extended data item MUST NOT be returned unless the 2463 client has specified the RECURSIVEMATCH selection option. 2465 The CHILDINFO extended data item in a LIST response describes the 2466 selection criteria that has caused it to be returned and indicates 2467 that the mailbox has at least one descendant mailbox that matches the 2468 selection criteria. 2470 Note: Some servers allow for mailboxes to exist without requiring 2471 their parent to exist. For example, a mailbox "Customers/ABC" can 2472 exist while the mailbox "Customers" does not. As CHILDINFO extended 2473 data item is not allowed if the RECURSIVEMATCH selection option is 2474 not specified, such servers SHOULD use the "\NonExistent 2475 \HasChildren" attribute pair to signal to the client that there is a 2476 descendant mailbox that matches the selection criteria. See example 2477 11 in Section 6.3.9.8. 2479 The returned selection criteria allow the client to distinguish a 2480 solicited response from an unsolicited one, as well as to distinguish 2481 among solicited responses caused by multiple pipelined LIST commands 2482 that specify different criteria. 2484 Servers SHOULD only return a non-matching mailbox name along with 2485 CHILDINFO if at least one matching child is not also being returned. 2486 That is, servers SHOULD suppress redundant CHILDINFO responses. 2488 Examples 8 and 10 in Section 6.3.9.8 demonstrate the difference 2489 between present CHILDINFO extended data item and the "\HasChildren" 2490 attribute. 2492 The following table summarizes interaction between the "\NonExistent" 2493 attribute and CHILDINFO (the first column indicates whether the 2494 parent mailbox exists): 2496 +--------+-------------+------------------+-------------------------+ 2497 | exists | meets the | has a child that | returned | 2498 | | selection | meets the | IMAP4rev2/LIST-EXTENDED | 2499 | | criteria | selection | attributes and | 2500 | | | criteria | CHILDINFO | 2501 +--------+-------------+------------------+-------------------------+ 2502 | no | no | no | no LIST response | 2503 | | | | returned | 2504 | yes | no | no | no LIST response | 2505 | | | | returned | 2506 | no | yes | no | (\NonExistent ) | 2507 | yes | yes | no | () | 2508 | no | no | yes | (\NonExistent) + | 2509 | | | | CHILDINFO | 2510 | yes | no | yes | () + CHILDINFO | 2511 | no | yes | yes | (\NonExistent ) + | 2512 | | | | CHILDINFO | 2513 | yes | yes | yes | () + CHILDINFO | 2514 +--------+-------------+------------------+-------------------------+ 2516 where is one or more attributes that correspond to the 2517 selection criteria; for example, for the SUBSCRIBED option the 2518 is \Subscribed. 2520 6.3.9.7. OLDNAME Extended Data Item 2522 The OLDNAME extended data item is included when a mailbox name is 2523 created (with CREATE command), renamed (with RENAME command) or 2524 deleted (with DELETE command). (When a mailbox is deleted the 2525 "\NonExistent" attribute is also included.) IMAP extensions can 2526 specify other conditions when OLDNAME extended data item should be 2527 included. 2529 If the server allows de-normalized mailbox names (see Section 5.1) in 2530 SELECT/EXAMINE, CREATE, RENAME or DELETE, it SHOULD return an 2531 unsolicited LIST response that includes OLDNAME extended data item, 2532 whenever the supplied mailbox name differs from the resulting 2533 normalized mailbox name. From the client point of view this is 2534 indistinguishable from another user renaming or deleting the mailbox, 2535 as specified in the previous paragraph. 2537 A deleted mailbox can be announced like this: 2539 S: * LIST (\NonExistent) "." "INBOX.DeletedMailbox" 2541 Example of a renamed mailbox: 2543 S: * LIST () "/" "NewMailbox" ("OLDNAME" ("OldMailbox")) 2545 6.3.9.8. LIST Command Examples 2547 This example shows some uses of the basic LIST command: 2549 Example: C: A101 LIST "" "" 2550 S: * LIST (\Noselect) "/" "" 2551 S: A101 OK LIST Completed 2552 C: A102 LIST #news.comp.mail.misc "" 2553 S: * LIST (\Noselect) "." #news. 2554 S: A102 OK LIST Completed 2555 C: A103 LIST /usr/staff/jones "" 2556 S: * LIST (\Noselect) "/" / 2557 S: A103 OK LIST Completed 2558 C: A202 LIST ~/Mail/ % 2559 S: * LIST (\Noselect) "/" ~/Mail/foo 2560 S: * LIST () "/" ~/Mail/meetings 2561 S: A202 OK LIST completed 2563 Extended examples: 2565 1: The first example shows the complete local hierarchy that will 2566 be used for the other examples. 2568 C: A01 LIST "" "*" 2569 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2570 S: * LIST () "/" "Fruit" 2571 S: * LIST () "/" "Fruit/Apple" 2572 S: * LIST () "/" "Fruit/Banana" 2573 S: * LIST () "/" "Tofu" 2574 S: * LIST () "/" "Vegetable" 2575 S: * LIST () "/" "Vegetable/Broccoli" 2576 S: * LIST () "/" "Vegetable/Corn" 2577 S: A01 OK done 2579 2: In the next example, we will see the subscribed mailboxes. This 2580 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2582 that the mailbox called "Fruit/Peach" is subscribed to, but does 2583 not actually exist (perhaps it was deleted while still 2584 subscribed). The "Fruit" mailbox is not subscribed to, but it 2585 has two subscribed children. The "Vegetable" mailbox is 2586 subscribed and has two children; one of them is subscribed as 2587 well. 2589 C: A02 LIST (SUBSCRIBED) "" "*" 2590 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2591 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2592 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2593 S: * LIST (\Subscribed) "/" "Vegetable" 2594 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2595 S: A02 OK done 2597 3: The next example shows the use of the CHILDREN option. The 2598 client, without having to list the second level of hierarchy, 2599 now knows which of the top-level mailboxes have submailboxes 2600 (children) and which do not. Note that it's not necessary for 2601 the server to return the \HasNoChildren attribute for the inbox, 2602 because the \NoInferiors attribute already implies that, and has 2603 a stronger meaning. 2605 C: A03 LIST () "" "%" RETURN (CHILDREN) 2606 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2607 S: * LIST (\HasChildren) "/" "Fruit" 2608 S: * LIST (\HasNoChildren) "/" "Tofu" 2609 S: * LIST (\HasChildren) "/" "Vegetable" 2610 S: A03 OK done 2612 4: In this example, we see more mailboxes that reside on another 2613 server. This is similar to the command . 2615 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2616 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2617 S: * LIST (\HasChildren) "/" "Fruit" 2618 S: * LIST (\HasNoChildren) "/" "Tofu" 2619 S: * LIST (\HasChildren) "/" "Vegetable" 2620 S: * LIST (\Remote) "/" "Bread" 2621 S: * LIST (\HasChildren \Remote) "/" "Meat" 2622 S: A04 OK done 2624 5: The following example also requests the server to include 2625 mailboxes that reside on another server. The server returns 2626 information about all mailboxes that are subscribed. This is 2627 similar to the command (see [RFC2193] for more 2628 details on RLSUB). We also see the use of two selection 2629 options. 2631 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2632 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2633 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2634 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2635 S: * LIST (\Subscribed) "/" "Vegetable" 2636 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2637 S: * LIST (\Remote \Subscribed) "/" "Bread" 2638 S: A05 OK done 2640 6: The following example requests the server to include mailboxes 2641 that reside on another server. The server is asked to return 2642 subscription information for all returned mailboxes. This is 2643 different from the example above. 2645 Note that the output of this command is not a superset of the 2646 output in the previous example, as it doesn't include LIST 2647 response for the non-existent "Fruit/Peach". 2649 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2650 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2651 S: * LIST () "/" "Fruit" 2652 S: * LIST () "/" "Fruit/Apple" 2653 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2654 S: * LIST () "/" "Tofu" 2655 S: * LIST (\Subscribed) "/" "Vegetable" 2656 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2657 S: * LIST () "/" "Vegetable/Corn" 2658 S: * LIST (\Remote \Subscribed) "/" "Bread" 2659 S: * LIST (\Remote) "/" "Meat" 2660 S: A06 OK done 2662 7: The following example demonstrates the difference between the 2663 \HasChildren attribute and the CHILDINFO extended data item. 2665 Let's assume there is the following hierarchy: 2667 C: C01 LIST "" "*" 2668 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2669 S: * LIST () "/" "Foo" 2670 S: * LIST () "/" "Foo/Bar" 2671 S: * LIST () "/" "Foo/Baz" 2672 S: * LIST () "/" "Moo" 2673 S: C01 OK done 2675 If the client asks RETURN (CHILDREN), it will get this: 2677 C: CA3 LIST "" "%" RETURN (CHILDREN) 2678 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2679 S: * LIST (\HasChildren) "/" "Foo" 2680 S: * LIST (\HasNoChildren) "/" "Moo" 2681 S: CA3 OK done 2683 A) Let's also assume that the mailbox "Foo/Baz" is the only 2684 subscribed mailbox. Then we get this result: 2686 C: C02 LIST (SUBSCRIBED) "" "*" 2687 S: * LIST (\Subscribed) "/" "Foo/Baz" 2688 S: C02 OK done 2690 Now, if the client issues , the server 2691 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2692 "Inbox" are NOT subscribed). However, if the client issues 2693 this: 2695 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2696 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2697 S: C04 OK done 2699 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2700 that is.) 2702 A1) If the mailbox "Foo" had also been subscribed, the last 2703 command would return this: 2705 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2706 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2707 S: C04 OK done 2709 or even this: 2711 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2712 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2713 ("SUBSCRIBED")) 2714 S: C04 OK done 2716 A2) If we assume instead that the mailbox "Foo" is not part of 2717 the original hierarchy and is not subscribed, the last command 2718 will give this result: 2720 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2721 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2722 S: C04 OK done 2724 B) Now, let's assume that no mailbox is subscribed. In this 2725 case, the command will 2726 return no responses, as there are no subscribed children (even 2727 though "Foo" has children). 2729 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2730 are subscribed. In that case, we see this result: 2732 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2733 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2734 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2735 S: C04 OK done 2737 (which means that the mailbox "Foo" has children, but none of 2738 them is subscribed). 2740 8: The following example demonstrates that the CHILDINFO extended 2741 data item is returned whether or not children mailboxes match 2742 the canonical LIST pattern. 2744 Let's assume there is the following hierarchy: 2746 C: D01 LIST "" "*" 2747 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2748 S: * LIST () "/" "foo2" 2749 S: * LIST () "/" "foo2/bar1" 2750 S: * LIST () "/" "foo2/bar2" 2751 S: * LIST () "/" "baz2" 2752 S: * LIST () "/" "baz2/bar2" 2753 S: * LIST () "/" "baz2/bar22" 2754 S: * LIST () "/" "baz2/bar222" 2755 S: * LIST () "/" "eps2" 2756 S: * LIST () "/" "eps2/mamba" 2757 S: * LIST () "/" "qux2/bar2" 2758 S: D01 OK done 2759 And that the following mailboxes are subscribed: 2761 C: D02 LIST (SUBSCRIBED) "" "*" 2762 S: * LIST (\Subscribed) "/" "foo2/bar1" 2763 S: * LIST (\Subscribed) "/" "foo2/bar2" 2764 S: * LIST (\Subscribed) "/" "baz2/bar2" 2765 S: * LIST (\Subscribed) "/" "baz2/bar22" 2766 S: * LIST (\Subscribed) "/" "baz2/bar222" 2767 S: * LIST (\Subscribed) "/" "eps2" 2768 S: * LIST (\Subscribed) "/" "eps2/mamba" 2769 S: * LIST (\Subscribed) "/" "qux2/bar2" 2770 S: D02 OK done 2772 The client issues the following command first: 2774 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2775 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2776 S: * LIST (\Subscribed) "/" "foo2/bar2" 2777 S: * LIST (\Subscribed) "/" "baz2/bar2" 2778 S: * LIST (\Subscribed) "/" "baz2/bar22" 2779 S: * LIST (\Subscribed) "/" "baz2/bar222" 2780 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2781 S: * LIST (\Subscribed) "/" "qux2/bar2" 2782 S: D03 OK done 2784 and the server may also include (but this would violate a SHOULD 2785 NOT in Section 3.5, because CHILDINFO is redundant) 2787 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2788 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2790 The CHILDINFO extended data item is returned for mailboxes 2791 "foo2", "baz2", and "eps2", because all of them have subscribed 2792 children, even though for the mailbox "foo2" only one of the two 2793 subscribed children matches the pattern, for the mailbox "baz2" 2794 all the subscribed children match the pattern, and for the 2795 mailbox "eps2" none of the subscribed children matches the 2796 pattern. 2798 Note that if the client issues 2800 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2801 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2802 S: * LIST (\Subscribed) "/" "foo2/bar1" 2803 S: * LIST (\Subscribed) "/" "foo2/bar2" 2804 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2805 S: * LIST (\Subscribed) "/" "baz2/bar2" 2806 S: * LIST (\Subscribed) "/" "baz2/bar22" 2807 S: * LIST (\Subscribed) "/" "baz2/bar222" 2808 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2809 S: * LIST (\Subscribed) "/" "eps2/mamba" 2810 S: * LIST (\Subscribed) "/" "qux2/bar2" 2811 S: D03 OK done 2813 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2814 still have the CHILDINFO extended data item, even though this 2815 information is redundant and the client can determine it by 2816 itself. 2818 9: The following example shows usage of extended syntax for mailbox 2819 pattern. It also demonstrates that the presence of the 2820 CHILDINFO extended data item doesn't necessarily imply 2821 \HasChildren. 2823 C: a1 LIST "" ("foo") 2824 S: * LIST () "/" foo 2825 S: a1 OK done 2827 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2828 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2829 S: a2 OK done 2831 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2832 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2833 S: a3 OK done 2835 10: The following example shows how a server that supports missing 2836 mailbox hierarchy elements can signal to a client that didn't 2837 specify the RECURSIVEMATCH selection option that there is a 2838 child mailbox that matches the selection criteria. 2840 C: a1 LIST (REMOTE) "" * 2841 S: * LIST () "/" music/rock 2842 S: * LIST (\Remote) "/" also/jazz 2843 S: a1 OK done 2845 C: a2 LIST () "" % 2846 S: * LIST (\NonExistent \HasChildren) "/" music 2847 S: a2 OK done 2849 C: a3 LIST (REMOTE) "" % 2850 S: * LIST (\NonExistent \HasChildren) "/" music 2851 S: * LIST (\NonExistent \HasChildren) "/" also 2852 S: a3 OK done 2854 C: a3.1 LIST "" (% music/rock) 2855 S: * LIST () "/" music/rock 2856 S: a3.1 OK done 2858 Because "music/rock" is the only mailbox under "music", there's 2859 no need for the server to also return "music". However clients 2860 must handle both cases. 2862 11: The following examples show use of STATUS return option. 2864 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2865 S: * LIST () "." "INBOX" 2866 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2867 S: * LIST () "." "foo" 2868 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2869 S: * LIST (\NoSelect) "." "bar" 2870 S: A01 OK List completed. 2872 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2874 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2875 (MESSAGES)) 2876 S: * LIST (\Subscribed) "." "INBOX" 2877 S: * STATUS "INBOX" (MESSAGES 17) 2878 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2879 S: A02 OK List completed. 2881 The LIST reply for "foo" is returned because it has matching 2882 children, but no STATUS reply is returned because "foo" itself 2883 doesn't match the selection criteria. 2885 6.3.10. NAMESPACE Command 2887 Arguments: none 2889 Responses: REQUIRED untagged responses: NAMESPACE 2891 Result: OK - command completed 2892 NO - Can't complete the command 2893 BAD - arguments invalid 2895 The NAMESPACE command causes a single untagged NAMESPACE response to 2896 be returned. The untagged NAMESPACE response contains the prefix and 2897 hierarchy delimiter to the server's Personal Namespace(s), Other 2898 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2899 to expose. The response will contain a NIL for any namespace class 2900 that is not available. The Namespace-Response-Extensions ABNF non 2901 terminal is defined for extensibility and MAY be included in the 2902 NAMESPACE response. 2904 Example 1: 2906 In this example a server supports a single personal namespace. No 2907 leading prefix is used on personal mailboxes and "/" is the hierarchy 2908 delimiter. 2910 C: A001 NAMESPACE 2911 S: * NAMESPACE (("" "/")) NIL NIL 2912 S: A001 OK NAMESPACE command completed 2914 Example 2: 2916 A user logged on anonymously to a server. No personal mailboxes are 2917 associated with the anonymous user and the user does not have access 2918 to the Other Users' Namespace. No prefix is required to access 2919 shared mailboxes and the hierarchy delimiter is "." 2921 C: A001 NAMESPACE 2922 S: * NAMESPACE NIL NIL (("" ".")) 2923 S: A001 OK NAMESPACE command completed 2925 Example 3: 2927 A server that contains a Personal Namespace and a single Shared 2928 Namespace. 2930 C: A001 NAMESPACE 2931 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2932 S: A001 OK NAMESPACE command completed 2934 Example 4: 2936 A server that contains a Personal Namespace, Other Users' Namespace 2937 and multiple Shared Namespaces. Note that the hierarchy delimiter 2938 used within each namespace can be different. 2940 C: A001 NAMESPACE 2941 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2942 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2943 S: A001 OK NAMESPACE command completed 2945 The prefix string allows a client to do things such as automatically 2946 creating personal mailboxes or LISTing all available mailboxes within 2947 a namespace. 2949 Example 5: 2951 A server that supports only the Personal Namespace, with a leading 2952 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2953 "." 2955 C: A001 NAMESPACE 2956 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2957 S: A001 OK NAMESPACE command completed 2959 < Automatically create a mailbox to store sent items.> 2961 C: A002 CREATE "INBOX.Sent Mail" 2962 S: A002 OK CREATE command completed 2964 Although typically a server will support only a single Personal 2965 Namespace, and a single Other User's Namespace, circumstances exist 2966 where there MAY be multiples of these, and a client MUST be prepared 2967 for them. If a client is configured such that it is required to 2968 create a certain mailbox, there can be circumstances where it is 2969 unclear which Personal Namespaces it should create the mailbox in. 2970 In these situations a client SHOULD let the user select which 2971 namespaces to create the mailbox in or just use the first personal 2972 namespace. 2974 Example 6: 2976 In this example, a server supports two Personal Namespaces. In 2977 addition to the regular Personal Namespace, the user has an 2978 additional personal namespace to allow access to mailboxes in an MH 2979 format mailstore. 2981 The client is configured to save a copy of all mail sent by the user 2982 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2983 deleted from a mailbox, the client is configured to move that message 2984 to a mailbox called 'Deleted Items'. 2986 Note that this example demonstrates how some extension parameters can 2987 be passed to further describe the #mh namespace. See the fictitious 2988 "X-PARAM" extension parameter. 2990 C: A001 NAMESPACE 2991 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2992 ("FLAG1" "FLAG2"))) NIL NIL 2993 S: A001 OK NAMESPACE command completed 2995 < It is desired to keep only one copy of sent mail. 2996 It is unclear which Personal Namespace the client 2997 should use to create the 'Sent Mail' mailbox. 2998 The user is prompted to select a namespace and only 2999 one 'Sent Mail' mailbox is created. > 3001 C: A002 CREATE "Sent Mail" 3002 S: A002 OK CREATE command completed 3004 < The client is designed so that it keeps two 3005 'Deleted Items' mailboxes, one for each namespace. > 3007 C: A003 CREATE "Delete Items" 3008 S: A003 OK CREATE command completed 3010 C: A004 CREATE "#mh/Deleted Items" 3011 S: A004 OK CREATE command completed 3013 The next level of hierarchy following the Other Users' Namespace 3014 prefix SHOULD consist of , where is a user name 3015 as per the LOGIN or AUTHENTICATE command. 3017 A client can construct a LIST command by appending a "%" to the Other 3018 Users' Namespace prefix to discover the Personal Namespaces of other 3019 users that are available to the currently authenticated user. 3021 In response to such a LIST command, a server SHOULD NOT return user 3022 names that have not granted access to their personal mailboxes to the 3023 user in question. 3025 A server MAY return a LIST response containing only the names of 3026 users that have explicitly granted access to the user in question. 3028 Alternatively, a server MAY return NO to such a LIST command, 3029 requiring that a user name be included with the Other Users' 3030 Namespace prefix before listing any other user's mailboxes. 3032 Example 7: 3034 A server that supports providing a list of other user's mailboxes 3035 that are accessible to the currently logged on user. 3037 C: A001 NAMESPACE 3038 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 3039 S: A001 OK NAMESPACE command completed 3041 C: A002 LIST "" "Other Users/%" 3042 S: * LIST () "/" "Other Users/Mike" 3043 S: * LIST () "/" "Other Users/Karen" 3044 S: * LIST () "/" "Other Users/Matthew" 3045 S: * LIST () "/" "Other Users/Tesa" 3046 S: A002 OK LIST command completed 3048 Example 8: 3050 A server that does not support providing a list of other user's 3051 mailboxes that are accessible to the currently logged on user. The 3052 mailboxes are listable if the client includes the name of the other 3053 user with the Other Users' Namespace prefix. 3055 C: A001 NAMESPACE 3056 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 3057 S: A001 OK NAMESPACE command completed 3059 < In this example, the currently logged on user has access to 3060 the Personal Namespace of user Mike, but the server chose to 3061 suppress this information in the LIST response. However, 3062 by appending the user name Mike (received through user input) 3063 to the Other Users' Namespace prefix, the client is able 3064 to get a listing of the personal mailboxes of user Mike. > 3066 C: A002 LIST "" "#Users/%" 3067 S: A002 NO The requested item could not be found. 3069 C: A003 LIST "" "#Users/Mike/%" 3070 S: * LIST () "/" "#Users/Mike/INBOX" 3071 S: * LIST () "/" "#Users/Mike/Foo" 3072 S: A003 OK LIST command completed. 3074 A prefix string might not contain a hierarchy delimiter, because in 3075 some cases it is not needed as part of the prefix. 3077 Example 9: 3079 A server that allows access to the Other Users' Namespace by 3080 prefixing the others' mailboxes with a '~' followed by , 3081 where is a user name as per the LOGIN or AUTHENTICATE 3082 command. 3084 C: A001 NAMESPACE 3085 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 3086 S: A001 OK NAMESPACE command completed 3088 < List the mailboxes for user mark > 3090 C: A002 LIST "" "~mark/%" 3091 S: * LIST () "/" "~mark/INBOX" 3092 S: * LIST () "/" "~mark/foo" 3093 S: A002 OK LIST command completed 3095 6.3.11. STATUS Command 3097 Arguments: mailbox name 3098 status data item names 3100 Responses: REQUIRED untagged responses: STATUS 3102 Result: OK - status completed 3103 NO - status failure: no status for that name 3104 BAD - command unknown or arguments invalid 3106 The STATUS command requests the status of the indicated mailbox. It 3107 does not change the currently selected mailbox, nor does it affect 3108 the state of any messages in the queried mailbox. 3110 The STATUS command provides an alternative to opening a second 3111 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3112 query that mailbox's status without deselecting the current mailbox 3113 in the first IMAP4rev2 connection. 3115 Unlike the LIST command, the STATUS command is not guaranteed to be 3116 fast in its response. Under certain circumstances, it can be quite 3117 slow. In some implementations, the server is obliged to open the 3118 mailbox read-only internally to obtain certain status information. 3119 Also unlike the LIST command, the STATUS command does not accept 3120 wildcards. 3122 Note: The STATUS command is intended to access the status of 3123 mailboxes other than the currently selected mailbox. Because the 3124 STATUS command can cause the mailbox to be opened internally, and 3125 because this information is available by other means on the 3126 selected mailbox, the STATUS command SHOULD NOT be used on the 3127 currently selected mailbox. However, servers MUST be able to 3128 execute STATUS command on the selected mailbox. (This might also 3129 implicitly happen when STATUS return option is used in a LIST 3130 command). 3132 The STATUS command MUST NOT be used as a "check for new messages 3133 in the selected mailbox" operation (refer to Section 7 and 3134 Section 7.3.1 for more information about the proper method for new 3135 message checking). 3137 STATUS SIZE (see below) can take a significant amount of time, 3138 depending upon server implementation. Clients should use STATUS 3139 SIZE cautiously. 3141 The currently defined status data items that can be requested are: 3143 MESSAGES The number of messages in the mailbox. 3145 UIDNEXT The next unique identifier value of the mailbox. Refer to 3146 Section 2.3.1.1 for more information. 3148 UIDVALIDITY The unique identifier validity value of the mailbox. 3149 Refer to Section 2.3.1.1 for more information. 3151 UNSEEN The number of messages which do not have the \Seen flag set. 3153 DELETED The number of messages which have the \Deleted flag set. 3155 SIZE The total size of the mailbox in octets. This is not strictly 3156 required to be an exact value, but it MUST be equal to or greater 3157 than the sum of the values of the RFC822.SIZE FETCH message data 3158 items (see Section 6.4.5) of all messages in the mailbox. 3160 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3161 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3162 S: A042 OK STATUS completed 3164 6.3.12. APPEND Command 3166 Arguments: mailbox name 3167 OPTIONAL flag parenthesized list 3168 OPTIONAL date/time string 3169 message literal 3171 Responses: OPTIONAL untagged response: LIST 3172 Result: OK - append completed 3173 NO - append error: can't append to that mailbox, error 3174 in flags or date/time or message text 3175 BAD - command unknown or arguments invalid 3177 The APPEND command appends the literal argument as a new message to 3178 the end of the specified destination mailbox. This argument SHOULD 3179 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3180 characters are permitted in the message. A server implementation 3181 that is unable to preserve 8-bit data properly MUST be able to 3182 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3183 content transfer encoding. 3185 Note: There may be exceptions, e.g., draft messages, in which 3186 required [RFC-5322] header fields are omitted in the message 3187 literal argument to APPEND. The full implications of doing so 3188 must be understood and carefully weighed. 3190 If a flag parenthesized list is specified, the flags SHOULD be set in 3191 the resulting message; otherwise, the flag list of the resulting 3192 message is set to empty by default. 3194 If a date-time is specified, the internal date SHOULD be set in the 3195 resulting message; otherwise, the internal date of the resulting 3196 message is set to the current date and time by default. 3198 If the append is unsuccessful for any reason, the mailbox MUST be 3199 restored to its state before the APPEND attempt (other than possibly 3200 keeping the changed mailbox's UIDNEXT value); no partial appending is 3201 permitted. 3203 If the destination mailbox does not exist, a server MUST return an 3204 error, and MUST NOT automatically create the mailbox. Unless it is 3205 certain that the destination mailbox can not be created, the server 3206 MUST send the response code "[TRYCREATE]" as the prefix of the text 3207 of the tagged NO response. This gives a hint to the client that it 3208 can attempt a CREATE command and retry the APPEND if the CREATE is 3209 successful. 3211 On successful completion of an APPEND, the server SHOULD return an 3212 APPENDUID response code (see Section 7.1). 3214 In the case of a mailbox that has permissions set so that the client 3215 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3216 SHOULD NOT send an APPENDUID response code as it would disclose 3217 information about the mailbox. 3219 In the case of a mailbox that has UIDNOTSTICKY status (see 3220 Section 7.1), the server MAY omit the APPENDUID response code as it 3221 is not meaningful. 3223 If the server does not return the APPENDUID response codes, the 3224 client can discover this information by selecting the destination 3225 mailbox. The location of messages placed in the destination mailbox 3226 by APPEND can be determined by using FETCH and/or SEARCH commands 3227 (e.g., for Message-ID or some unique marker placed in the message in 3228 an APPEND). 3230 If the mailbox is currently selected, the normal new message actions 3231 SHOULD occur. Specifically, the server SHOULD notify the client 3232 immediately via an untagged EXISTS response. If the server does not 3233 do so, the client MAY issue a NOOP command after one or more APPEND 3234 commands. 3236 If the server decides to convert (normalize) the mailbox name, it 3237 SHOULD return an untagged LIST with OLDNAME extended data item, with 3238 the OLDNAME value being the supplied mailbox name and the name 3239 parameter being the normalized mailbox name. (See Section 6.3.9.7 3240 for more details.) 3242 Example: C: A003 APPEND saved-messages (\Seen) {310} 3243 S: + Ready for literal data 3244 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3245 C: From: Fred Foobar 3246 C: Subject: afternoon meeting 3247 C: To: mooch@owatagu.siam.edu 3248 C: Message-Id: 3249 C: MIME-Version: 1.0 3250 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3251 C: 3252 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3253 C: 3254 S: A003 OK APPEND completed 3256 Example: C: A003 APPEND saved-messages (\Seen) {297} 3257 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3258 C: From: Fred Foobar 3259 C: Subject: afternoon meeting 3260 C: To: mooch@example.com 3261 C: Message-Id: 3262 C: MIME-Version: 1.0 3263 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3264 C: 3265 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3266 C: 3267 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3268 C: A004 COPY 2:4 meeting 3269 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3270 C: A005 UID COPY 305:310 meeting 3271 S: A005 OK No matching messages, so nothing copied 3272 C: A006 COPY 2 funny 3273 S: A006 OK Done 3274 C: A007 SELECT funny 3275 S: * 1 EXISTS 3276 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3277 S: * OK [UIDNEXT 2] Predicted next UID 3278 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3279 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3280 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3281 S: * LIST () "." funny 3282 S: A007 OK [READ-WRITE] SELECT completed 3284 In this example, A003 and A004 demonstrate successful appending and 3285 copying to a mailbox that returns the UIDs assigned to the messages. 3286 A005 is an example in which no messages were copied; this is because 3287 in A003, we see that message 2 had UID 304, and message 3 had UID 3288 319; therefore, UIDs 305 through 310 do not exist (refer to 3289 Section 2.3.1.1 for further explanation). A006 is an example of a 3290 message being copied that did not return a COPYUID; and, as expected, 3291 A007 shows that the mail store containing that mailbox does not 3292 support persistent UIDs. 3294 Note: The APPEND command is not used for message delivery, because 3295 it does not provide a mechanism to transfer [SMTP] envelope 3296 information. 3298 6.3.13. IDLE Command 3300 Arguments: none 3302 Responses: continuation data will be requested; the client sends the 3303 continuation data "DONE" to end the command 3305 Result: OK - IDLE completed after client sent "DONE" 3306 NO - failure: the server will not allow the IDLE command 3307 at this time 3308 BAD - command unknown or arguments invalid 3310 Without the IDLE command a client would need to poll the server for 3311 changes to the selected mailbox (new mail, deletions, flag changes). 3312 It's often more desirable to have the server transmit updates to the 3313 client in real time. This allows a user to see new mail immediately. 3314 The IDLE command allows a client to tell the server that it's ready 3315 to accept such real-time updates. 3317 The IDLE command is sent from the client to the server when the 3318 client is ready to accept unsolicited update messages. The server 3319 requests a response to the IDLE command using the continuation ("+") 3320 response. The IDLE command remains active until the client responds 3321 to the continuation, and as long as an IDLE command is active, the 3322 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3323 responses at any time. If the server chooses to send unsolicited 3324 FETCH responses, they MUST include UID FETCH item. 3326 The IDLE command is terminated by the receipt of a "DONE" 3327 continuation from the client; such response satisfies the server's 3328 continuation request. At that point, the server MAY send any 3329 remaining queued untagged responses and then MUST immediately send 3330 the tagged response to the IDLE command and prepare to process other 3331 commands. As for other commands, the processing of any new command 3332 may cause the sending of unsolicited untagged responses, subject to 3333 the ambiguity limitations. The client MUST NOT send a command while 3334 the server is waiting for the DONE, since the server will not be able 3335 to distinguish a command from a continuation. 3337 The server MAY consider a client inactive if it has an IDLE command 3338 running, and if such a server has an inactivity timeout it MAY log 3339 the client off implicitly at the end of its timeout period. Because 3340 of that, clients using IDLE are advised to terminate the IDLE and re- 3341 issue it at least every 29 minutes to avoid being logged off. This 3342 still allows a client to receive immediate mailbox updates even 3343 though it need only "poll" at half hour intervals. 3345 Example: C: A001 SELECT INBOX 3346 S: * FLAGS (\Deleted \Seen \Flagged) 3347 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3348 S: * 3 EXISTS 3349 S: * OK [UIDVALIDITY 1] 3350 S: * LIST () "/" INBOX 3351 S: A001 OK [READ-WRITE] SELECT completed 3352 C: A002 IDLE 3353 S: + idling 3354 ...time passes; new mail arrives... 3355 S: * 4 EXISTS 3356 C: DONE 3357 S: A002 OK IDLE terminated 3358 ...another client expunges message 2 now... 3359 C: A003 FETCH 4 ALL 3360 S: * 4 FETCH (...) 3361 S: A003 OK FETCH completed 3362 C: A004 IDLE 3363 S: * 2 EXPUNGE 3364 S: * 3 EXISTS 3365 S: + idling 3366 ...time passes; another client expunges message 3... 3367 S: * 3 EXPUNGE 3368 S: * 2 EXISTS 3369 ...time passes; new mail arrives... 3370 S: * 3 EXISTS 3371 C: DONE 3372 S: A004 OK IDLE terminated 3373 C: A005 FETCH 3 ALL 3374 S: * 3 FETCH (...) 3375 S: A005 OK FETCH completed 3376 C: A006 IDLE 3378 6.4. Client Commands - Selected State 3380 In the selected state, commands that manipulate messages in a mailbox 3381 are permitted. 3383 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3384 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3385 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3386 APPEND), the following commands are valid in the selected state: 3387 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3389 6.4.1. CLOSE Command 3391 Arguments: none 3393 Responses: no specific responses for this command 3395 Result: OK - close completed, now in authenticated state 3396 BAD - command unknown or arguments invalid 3398 The CLOSE command permanently removes all messages that have the 3399 \Deleted flag set from the currently selected mailbox, and returns to 3400 the authenticated state from the selected state. No untagged EXPUNGE 3401 responses are sent. 3403 No messages are removed, and no error is given, if the mailbox is 3404 selected by an EXAMINE command or is otherwise selected read-only. 3406 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3407 MAY be issued without previously issuing a CLOSE command. The 3408 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3409 selected mailbox without doing an expunge. However, when many 3410 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3411 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3412 no untagged EXPUNGE responses (which the client would probably 3413 ignore) are sent. 3415 Example: C: A341 CLOSE 3416 S: A341 OK CLOSE completed 3418 6.4.2. UNSELECT Command 3420 Arguments: none 3422 Responses: no specific responses for this command 3424 Result: OK - unselect completed, now in authenticated state 3425 BAD - no mailbox selected, or argument supplied but none 3426 permitted 3428 The UNSELECT command frees session's resources associated with the 3429 selected mailbox and returns the server to the authenticated state. 3430 This command performs the same actions as CLOSE, except that no 3431 messages are permanently removed from the currently selected mailbox. 3433 Example: C: A342 UNSELECT 3434 S: A342 OK Unselect completed 3436 6.4.3. EXPUNGE Command 3438 Arguments: none 3440 Responses: untagged responses: EXPUNGE 3442 Result: OK - expunge completed 3443 NO - expunge failure: can't expunge (e.g., permission 3444 denied) 3445 BAD - command unknown or arguments invalid 3447 The EXPUNGE command permanently removes all messages that have the 3448 \Deleted flag set from the currently selected mailbox. Before 3449 returning an OK to the client, an untagged EXPUNGE response is sent 3450 for each message that is removed. 3452 Example: C: A202 EXPUNGE 3453 S: * 3 EXPUNGE 3454 S: * 3 EXPUNGE 3455 S: * 5 EXPUNGE 3456 S: * 8 EXPUNGE 3457 S: A202 OK EXPUNGE completed 3459 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3460 set. See the description of the EXPUNGE response for further 3461 explanation. 3463 6.4.4. SEARCH Command 3465 Arguments: OPTIONAL result specifier 3466 OPTIONAL [CHARSET] specification 3467 searching criteria (one or more) 3469 Responses: OPTIONAL untagged response: ESEARCH 3471 Result: OK - search completed 3472 NO - search error: can't search that [CHARSET] or 3473 criteria 3474 BAD - command unknown or arguments invalid 3476 The SEARCH command searches the mailbox for messages that match the 3477 given searching criteria. 3479 The SEARCH command may contain result options. Result options 3480 control what kind of information is returned about messages matching 3481 the search criteria in an untagged ESEARCH response. If no result 3482 option is specified or empty list of options is specified "()", ALL 3483 is assumed (see below). The order of individual options is 3484 arbitrary. Individual options may contain parameters enclosed in 3485 parentheses. (However, if an option has a mandatory parameter, which 3486 can always be represented as a number or a sequence-set, the option 3487 parameter does not need the enclosing parentheses. See the ABNF for 3488 more details). If an option has parameters, they consist of atoms 3489 and/or strings and/or lists in a specific order. Any options not 3490 defined by extensions that the server supports MUST be rejected with 3491 a BAD response. 3493 This document specifies the following result options: 3495 MIN 3497 Return the lowest message number/UID that satisfies the SEARCH 3498 criteria. 3500 If the SEARCH results in no matches, the server MUST NOT 3501 include the MIN result option in the ESEARCH response; however, 3502 it still MUST send the ESEARCH response. 3504 MAX 3506 Return the highest message number/UID that satisfies the SEARCH 3507 criteria. 3509 If the SEARCH results in no matches, the server MUST NOT 3510 include the MAX result option in the ESEARCH response; however, 3511 it still MUST send the ESEARCH response. 3513 ALL 3515 Return all message numbers/UIDs that satisfy the SEARCH 3516 criteria using the sequence-set syntax. Note, the client MUST 3517 NOT assume that messages/UIDs will be listed in any particular 3518 order. 3520 If the SEARCH results in no matches, the server MUST NOT 3521 include the ALL result option in the ESEARCH response; however, 3522 it still MUST send the ESEARCH response. 3524 COUNT Return the number of messages that satisfy the SEARCH 3525 criteria. This result option MUST always be included in the 3526 ESEARCH response. 3528 SAVE 3530 This option tells the server to remember the result of the 3531 SEARCH or UID SEARCH command (as well as any command based on 3532 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3533 internal variable that we will reference as the "search result 3534 variable". The client can use the "$" marker to reference the 3535 content of this internal variable. The "$" marker can be used 3536 instead of message sequence or UID sequence in order to 3537 indicate that the server should substitute it with the list of 3538 messages from the search result variable. Thus, the client can 3539 use the result of the latest remembered SEARCH command as a 3540 parameter to another command. See Section 6.4.4.1 for details 3541 on how the value of the search result variable is determined, 3542 how it is affected by other commands executed, and how SAVE 3543 return option interacts with other return options. 3545 In absence of any other SEARCH result option, the SAVE result 3546 option also suppresses any ESEARCH response that would have 3547 been otherwise returned by the SEARCH command. 3549 Note: future extensions to this document can allow servers to return 3550 multiple ESEARCH responses for a single extended SEARCH command. 3551 However all options specified above MUST result in a single ESEARCH 3552 response if used by themselves or in a combination. This guaranty 3553 simplifies processing in IMAP4rev2 clients. Future SEARCH extensions 3554 that relax this restriction will have to describe how results from 3555 multiple ESEARCH responses are to be amalgamated. 3557 Searching criteria consist of one or more search keys. 3559 When multiple keys are specified, the result is the intersection (AND 3560 function) of all the messages that match those keys. For example, 3561 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3562 deleted messages from Smith with INTERNALDATE greater than February 3563 1, 1994. A search key can also be a parenthesized list of one or 3564 more search keys (e.g., for use with the OR and NOT keys). 3566 Server implementations MAY exclude [MIME-IMB] body parts with 3567 terminal content media types other than TEXT and MESSAGE from 3568 consideration in SEARCH matching. 3570 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3571 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3572 [CHARSET] of the strings that appear in the search criteria. 3573 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3574 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3575 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3576 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3577 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3578 CHARSET UTF-8 is redundant. It is permitted for improved 3579 compatibility with existing IMAP4rev1 clients. 3581 If the server does not support the specified [CHARSET], it MUST 3582 return a tagged NO response (not a BAD). This response SHOULD 3583 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3584 supported by the server. 3586 In all search keys that use strings and unless specified otherwise, a 3587 message matches the key if the string is a substring of the 3588 associated text. The matching SHOULD be case-insensitive for 3589 characters within ASCII range. Consider using [IMAP-I18N] for 3590 language-sensitive case-insensitive searching. Note that the empty 3591 string is a substring; this is useful when doing a HEADER search in 3592 order to test for a header field presence in the message. 3594 The defined search keys are as follows. Refer to the Formal Syntax 3595 section for the precise syntactic definitions of the arguments. 3597 Messages with message sequence numbers corresponding 3598 to the specified message sequence number set. 3600 ALL All messages in the mailbox; the default initial key for ANDing. 3602 ANSWERED Messages with the \Answered flag set. 3604 BCC Messages that contain the specified string in the 3605 envelope structure's BCC field. 3607 BEFORE Messages whose internal date (disregarding time and 3608 timezone) is earlier than the specified date. 3610 BODY Messages that contain the specified string in the body 3611 of the message. Unlike TEXT (see below), this doesn't match any 3612 header fields. Servers are allowed to implement flexible matching 3613 for this search key, for example matching "swim" to both "swam" 3614 and "swum" in English language text or only doing full word 3615 matching (where "swim" will not match "swimming"). 3617 CC Messages that contain the specified string in the 3618 envelope structure's CC field. 3620 DELETED Messages with the \Deleted flag set. 3622 DRAFT Messages with the \Draft flag set. 3624 FLAGGED Messages with the \Flagged flag set. 3626 FROM Messages that contain the specified string in the 3627 envelope structure's FROM field. 3629 HEADER Messages that have a header field with 3630 the specified field-name (as defined in [RFC-5322]) and that 3631 contains the specified string in the text of the header field 3632 (what comes after the colon). If the string to search is zero- 3633 length, this matches all messages that have a header field with 3634 the specified field-name regardless of the contents. Servers 3635 should use substring search for this SEARCH item, as clients can 3636 use it for automatic processing not initiated by end users. For 3637 example this can be used for searching for Message-ID or Content- 3638 Type header field values that need to be exact, or for searches in 3639 header fields that the IMAP server might not know anything about. 3641 KEYWORD Messages with the specified keyword flag set. 3643 LARGER Messages with an [RFC-5322] size larger than the 3644 specified number of octets. 3646 NOT Messages that do not match the specified search 3647 key. 3649 ON Messages whose internal date (disregarding time and 3650 timezone) is within the specified date. 3652 OR Messages that match either search 3653 key. 3655 SEEN Messages that have the \Seen flag set. 3657 SENTBEFORE Messages whose [RFC-5322] Date: header field 3658 (disregarding time and timezone) is earlier than the specified 3659 date. 3661 SENTON Messages whose [RFC-5322] Date: header field 3662 (disregarding time and timezone) is within the specified date. 3664 SENTSINCE Messages whose [RFC-5322] Date: header field 3665 (disregarding time and timezone) is within or later than the 3666 specified date. 3668 SINCE Messages whose internal date (disregarding time and 3669 timezone) is within or later than the specified date. 3671 SMALLER Messages with an [RFC-5322] size smaller than the 3672 specified number of octets. 3674 SUBJECT Messages that contain the specified string in the 3675 envelope structure's SUBJECT field. 3677 TEXT Messages that contain the specified string in the 3678 header (including MIME header fields) or body of the message. 3679 Servers are allowed to implement flexible matching for this search 3680 key, for example matching "swim" to both "swam" and "swum" in 3681 English language text or only doing full word matching (where 3682 "swim" will not match "swimming"). 3684 TO Messages that contain the specified string in the 3685 envelope structure's TO field. 3687 UID Messages with unique identifiers corresponding to 3688 the specified unique identifier set. Sequence set ranges are 3689 permitted. 3691 UNANSWERED Messages that do not have the \Answered flag set. 3693 UNDELETED Messages that do not have the \Deleted flag set. 3695 UNDRAFT Messages that do not have the \Draft flag set. 3697 UNFLAGGED Messages that do not have the \Flagged flag set. 3699 UNKEYWORD Messages that do not have the specified keyword 3700 flag set. 3702 UNSEEN Messages that do not have the \Seen flag set. 3704 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3705 SINCE 1-Feb-1994 NOT FROM "Smith" 3706 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3707 S: A282 OK SEARCH completed 3709 Example: C: A283 SEARCH RETURN () FLAGGED 3710 SINCE 1-Feb-1994 NOT FROM "Smith" 3711 S: * ESEARCH (TAG "A283") ALL 2,10:11 3712 S: A283 OK SEARCH completed 3714 Example: C: A284 SEARCH TEXT "string not in mailbox" 3715 S: * ESEARCH (TAG "A284") 3716 S: A284 OK SEARCH completed 3717 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3718 S: + Ready for literal text 3719 C: XXXXXX 3720 S: * ESEARCH (TAG "A285") ALL 43 3721 S: A285 OK SEARCH completed 3723 Note: Since this document is restricted to 7-bit ASCII text, it is 3724 not possible to show actual UTF-8 data. The "XXXXXX" is a 3725 placeholder for what would be 6 octets of 8-bit data in an actual 3726 transaction. 3728 The following example demonstrates finding the first unseen message 3729 in the mailbox: 3731 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3732 S: * ESEARCH (TAG "A284") MIN 4 3733 S: A284 OK SEARCH completed 3735 The following example demonstrates that if the ESEARCH UID indicator 3736 is present, all data in the ESEARCH response is referring to UIDs; 3737 for example, the MIN result specifier will be followed by a UID. 3739 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3740 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3741 S: A285 OK SEARCH completed 3743 The following example demonstrates returning the number of deleted 3744 messages: 3746 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3747 S: * ESEARCH (TAG "A286") COUNT 15 3748 S: A286 OK SEARCH completed 3750 6.4.4.1. SAVE result option and SEARCH result variable 3752 Upon successful completion of a SELECT or an EXAMINE command (after 3753 the tagged OK response), the current search result variable is reset 3754 to the empty sequence. 3756 A successful SEARCH command with the SAVE result option sets the 3757 value of the search result variable to the list of messages found in 3758 the SEARCH command. For example, if no messages were found, the 3759 search result variable will contain the empty sequence. 3761 Any of the following SEARCH commands MUST NOT change the search 3762 result variable: 3764 a SEARCH command that caused the server to return the BAD tagged 3765 response, 3767 a SEARCH command with no SAVE result option that caused the server 3768 to return NO tagged response, 3770 a successful SEARCH command with no SAVE result option. 3772 A SEARCH command with the SAVE result option that caused the server 3773 to return the NO tagged response sets the value of the search result 3774 variable to the empty sequence. 3776 When a message listed in the search result variable is EXPUNGEd, it 3777 is automatically removed from the list. Implementors are reminded 3778 that if the server stores the list as a list of message numbers, it 3779 MUST automatically adjust them when notifying the client about 3780 expunged messages, as described in Section 7.4.1. 3782 If the server decides to send a new UIDVALIDITY value while the 3783 mailbox is opened, this causes resetting of the search variable to 3784 the empty sequence. 3786 Note that even if the "$" marker contains the empty sequence of 3787 messages, it must be treated by all commands accepting message sets 3788 as parameters as a valid, but non-matching list of messages. For 3789 example, the "FETCH $" command would return a tagged OK response and 3790 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3792 The SAVE result option doesn't change whether the server would return 3793 items corresponding to MIN, MAX, ALL, or COUNT result options. 3795 When the SAVE result option is combined with the MIN or MAX result 3796 option, and both ALL and COUNT result options are absent, the 3797 corresponding MIN/MAX is returned (if the search result is not 3798 empty), but the "$" marker would contain a single message as returned 3799 in the MIN/MAX return item. 3801 If the SAVE result option is combined with both MIN and MAX result 3802 options, and both ALL and COUNT result options are absent, the "$" 3803 marker would contain zero, one or two messages as returned in the 3804 MIN/MAX return items. 3806 If the SAVE result option is combined with the ALL and/or COUNT 3807 result option(s), the "$" marker would always contain all messages 3808 found by the SEARCH or UID SEARCH command. 3810 The following table summarizes the additional requirement on ESEARCH 3811 server implementations described in this section. 3813 +------------------------------+--------------------+ 3814 | Combination of Result option | "$" marker value | 3815 +------------------------------+--------------------+ 3816 | SAVE MIN | MIN | 3817 | SAVE MAX | MAX | 3818 | SAVE MIN MAX | MIN & MAX | 3819 | SAVE * [m] | all found messages | 3820 +------------------------------+--------------------+ 3822 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3823 and/or "MAX" 3825 Implementation note: server implementors should note that "$" can 3826 reference IMAP message sequences or UID sequences, depending on the 3827 context where it is used. For example, the "$" marker can be set as 3828 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3829 FETCH command (which accepts a UID sequence, not a message sequence), 3830 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3831 command and used as a parameter to a FETCH command (which accepts a 3832 message sequence, not a UID sequence). Server implementations need 3833 to automatically map the "$" marker value to message numbers or UIDs, 3834 depending on context where the "$" marker is used. 3836 6.4.4.2. Multiple Commands in Progress 3838 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3839 "$" marker creates direct dependency between the two commands. As 3840 directed by Section 5.5, a server MUST execute the two commands in 3841 the order they were received. 3843 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3844 command using the "$" marker, as long as this doesn't create an 3845 ambiguity, as described in Section 5.5. Examples 7-9 in 3846 Section 6.4.4.4 explain this in more details. 3848 6.4.4.3. Refusing to Save Search Results 3850 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3851 for example, if an internal limit on the number of saved results is 3852 reached. In this case, the server MUST return a tagged NO response 3853 containing the NOTSAVED response code and set the search result 3854 variable to the empty sequence, as described in Section 6.4.4.1. 3856 6.4.4.4. Examples showing use of SAVE result option 3858 Only in this section: explanatory comments in examples that start 3859 with // are not part of the protocol. 3861 1) The following example demonstrates how the client can use the 3862 result of a SEARCH command to FETCH headers of interesting messages: 3864 Example 1: 3865 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3866 NOT FROM "Smith" 3867 S: A282 OK SEARCH completed, result saved 3868 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3869 S: * 2 FETCH (UID 14 ... 3870 S: * 84 FETCH (UID 100 ... 3871 S: * 882 FETCH (UID 1115 ... 3872 S: A283 OK completed 3874 The client can also pipeline the two commands: 3876 Example 2: 3877 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3878 NOT FROM "Smith" 3879 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3880 S: A282 OK SEARCH completed 3881 S: * 2 FETCH (UID 14 ... 3882 S: * 84 FETCH (UID 100 ... 3883 S: * 882 FETCH (UID 1115 ... 3884 S: A283 OK completed 3886 2) The following example demonstrates that the result of one SEARCH 3887 command can be used as input to another SEARCH command: 3889 Example 3: 3890 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3891 NOT FROM "Smith" 3892 S: A300 OK SEARCH completed 3893 C: A301 UID SEARCH UID $ SMALLER 4096 3894 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3895 S: A301 OK completed 3897 Note that the second command in Example 3 can be replaced with: 3898 C: A301 UID SEARCH $ SMALLER 4096 3899 and the result of the command would be the same. 3901 3) The following example shows that the "$" marker can be combined 3902 with other message numbers using the OR SEARCH criterion. 3904 Example 4: 3905 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3906 NOT FROM "Smith" 3907 S: P282 OK SEARCH completed 3908 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3909 C: YYYYYYYY 3910 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3911 S: P283 OK completed 3913 Note: Since this document format is restricted to 7-bit ASCII text, 3914 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3915 placeholder for what would be 8 octets of 8-bit data in an actual 3916 transaction. 3918 4) The following example demonstrates that a failed SEARCH sets the 3919 search result variable to the empty list. The server doesn't 3920 implement the KOI8-R charset. 3922 Example 5: 3923 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3924 NOT FROM "Smith" 3925 S: B282 OK SEARCH completed 3926 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3927 (OR $ 1,3000:3021) TEXT {4} 3928 C: XXXX 3929 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3930 //After this command the saved result variable contains 3931 //no messages. A client that wants to reissue the B283 3932 //SEARCH command with another CHARSET would have to reissue 3933 //the B282 command as well. One possible workaround for 3934 //this is to include the desired CHARSET parameter 3935 //in the earliest SEARCH RETURN (SAVE) command in a 3936 //sequence of related SEARCH commands, to cause 3937 //the earliest SEARCH in the sequence to fail. 3938 //A better approach might be to always use CHARSET UTF-8 3939 //instead. 3941 Note: Since this document format is restricted to 7-bit ASCII text, 3942 it is not possible to show actual KOI8-R data. The "XXXX" is a 3943 placeholder for what would be 4 octets of 8-bit data in an actual 3944 transaction. 3946 5) The following example demonstrates that it is not an error to use 3947 the "$" marker when it contains no messages. 3949 Example 6: 3950 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3951 NOT FROM "Eric" 3952 C: E283 COPY $ "Other Messages" 3953 //The "$" contains no messages 3954 S: E282 OK SEARCH completed 3955 S: E283 OK COPY completed, nothing copied 3957 Example 7: 3958 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3959 C: F283 COPY $ "Junk" 3960 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3961 S: F282 OK SEARCH completed 3962 S: F283 OK COPY completed 3963 S: F284 OK STORE completed 3965 Example 8: 3966 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3967 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3968 FROM "Eric" 3969 // The server can execute the two SEARCH commands 3970 // in any order, as they don't have any dependency. 3971 // For example, it may return: 3972 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3973 S: G283 OK SEARCH completed 3974 S: G282 OK SEARCH completed 3976 The following example demonstrates that the result of the second 3977 SEARCH RETURN (SAVE) always overrides the result of the first. 3979 Example 9: 3980 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3981 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3982 FROM "Eric" 3983 S: H282 OK SEARCH completed 3984 S: H283 OK SEARCH completed 3985 // At this point "$" would contain results of H283 3987 The following example demonstrates behavioral difference for 3988 different combinations of ESEARCH result options. 3990 Example 10: 3991 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3992 NOT FROM "Smith" 3993 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3994 //$ value hasn't changed 3995 S: C282 OK SEARCH completed 3997 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3998 NOT FROM "Smith" 3999 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 4000 //$ value is 2,10:15,21 4001 S: C283 OK SEARCH completed 4003 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 4004 NOT FROM "Smith" 4005 S: * ESEARCH (TAG "C284") MIN 2 4006 //$ value is 2 4007 S: C284 OK SEARCH completed 4009 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 4010 12-Feb-2006 NOT FROM "Smith" 4011 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 4012 //$ value is 2,21 4013 S: C285 OK SEARCH completed 4015 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 4016 SINCE 12-Feb-2006 NOT FROM "Smith" 4017 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 4018 //$ value is 2,10:15,21 4019 S: C286 OK SEARCH completed 4021 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 4022 12-Feb-2006 NOT FROM "Smith" 4023 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 4024 //$ value is 2,10:15,21 4025 S: C286 OK SEARCH completed 4027 6.4.5. FETCH Command 4029 Arguments: sequence set 4030 message data item names or macro 4032 Responses: untagged responses: FETCH 4034 Result: OK - fetch completed 4035 NO - fetch error: can't fetch that data 4036 BAD - command unknown or arguments invalid 4038 The FETCH command retrieves data associated with a message in the 4039 mailbox. The data items to be fetched can be either a single atom or 4040 a parenthesized list. 4042 Most data items, identified in the formal syntax under the msg-att- 4043 static rule, are static and MUST NOT change for any particular 4044 message. Other data items, identified in the formal syntax under the 4045 msg-att-dynamic rule, MAY change, either as a result of a STORE 4046 command or due to external events. 4048 For example, if a client receives an ENVELOPE for a message when 4049 it already knows the envelope, it can safely ignore the newly 4050 transmitted envelope. 4052 There are three macros which specify commonly-used sets of data 4053 items, and can be used instead of data items. A macro must be used 4054 by itself, and not in conjunction with other macros or data items. 4056 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 4058 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 4060 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 4061 BODY) 4063 Several data items reference "section" or "section-binary". See 4064 Section 6.4.5.1 for their detailed definition. 4066 The currently defined data items that can be fetched are: 4068 BINARY[]<> 4070 Requests that the specified section be transmitted after 4071 performing Content-Transfer-Encoding-related decoding. 4073 The argument, if present, requests that a subset of 4074 the data be returned. The semantics of a partial FETCH BINARY 4075 command are the same as for a partial FETCH BODY command, with 4076 the exception that the arguments refer to the DECODED 4077 section data. 4079 Note that this data item can only be requested for leaf (i.e. 4080 non multipart/*, non message/rfc822 and non message/global) 4081 body parts. 4083 BINARY.PEEK[]<> An alternate form of 4084 BINARY[] that does not implicitly set the \Seen 4085 flag. 4087 BINARY.SIZE[] 4089 Requests the decoded size of the section (i.e., the size to 4090 expect in response to the corresponding FETCH BINARY request). 4092 Note: client authors are cautioned that this might be an 4093 expensive operation for some server implementations. 4094 Needlessly issuing this request could result in degraded 4095 performance due to servers having to calculate the value every 4096 time the request is issued. 4098 Note that this data item can only be requested for leaf (i.e. 4099 non multipart/*, non message/rfc822 and non message/global) 4100 body parts. 4102 BODY Non-extensible form of BODYSTRUCTURE. 4104 BODY[
]<> 4106 The text of a particular body section. 4108 It is possible to fetch a substring of the designated text. 4109 This is done by appending an open angle bracket ("<"), the 4110 octet position of the first desired octet, a period, the 4111 maximum number of octets desired, and a close angle bracket 4112 (">") to the part specifier. If the starting octet is beyond 4113 the end of the text, an empty string is returned. 4115 Any partial fetch that attempts to read beyond the end of the 4116 text is truncated as appropriate. A partial fetch that starts 4117 at octet 0 is returned as a partial fetch, even if this 4118 truncation happened. 4120 Note: This means that BODY[]<0.2048> of a 1500-octet message 4121 will return BODY[]<0> with a literal of size 1500, not 4122 BODY[]. 4124 Note: A substring fetch of a HEADER.FIELDS or 4125 HEADER.FIELDS.NOT part specifier is calculated after 4126 subsetting the header. 4128 The \Seen flag is implicitly set; if this causes the flags to 4129 change, they SHOULD be included as part of the FETCH responses. 4131 BODY.PEEK[
]<> An alternate form of BODY[
] 4132 that does not implicitly set the \Seen flag. 4134 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4135 computed by the server by parsing the [MIME-IMB] header fields in 4136 the [RFC-5322] header and [MIME-IMB] headers. See Section 7.4.2 4137 for more details. 4139 ENVELOPE The envelope structure of the message. This is computed by 4140 the server by parsing the [RFC-5322] header into the component 4141 parts, defaulting various fields as necessary. See Section 7.4.2 4142 for more details. 4144 FLAGS The flags that are set for this message. 4146 INTERNALDATE The internal date of the message. 4148 RFC822.SIZE The [RFC-5322] size of the message. 4150 UID The unique identifier for the message. 4152 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4153 S: * 2 FETCH .... 4154 S: * 3 FETCH .... 4155 S: * 4 FETCH .... 4156 S: A654 OK FETCH completed 4158 6.4.5.1. FETCH section specification 4160 Several FETCH data items reference "section" or "section-binary". 4161 The section specification is a set of zero or more part specifiers 4162 delimited by periods. A part specifier is either a part number or 4163 one of the following: HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, 4164 and TEXT. (Non numeric part specifiers have to be the last specifier 4165 in a section specification.) An empty section specification refers 4166 to the entire message, including the header. 4168 Every message has at least one part number. Non-[MIME-IMB] messages, 4169 and non-multipart [MIME-IMB] messages with no encapsulated message, 4170 only have a part 1. 4172 Multipart messages are assigned consecutive part numbers, as they 4173 occur in the message. If a particular part is of type message or 4174 multipart, its parts MUST be indicated by a period followed by the 4175 part number within that nested multipart part. 4177 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested part 4178 numbers, referring to parts of the MESSAGE part's body. 4180 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 4181 specifiers can be the sole part specifier or can be prefixed by one 4182 or more numeric part specifiers, provided that the numeric part 4183 specifier refers to a part of type MESSAGE/RFC822 or MESSAGE/GLOBAL. 4184 The MIME part specifier MUST be prefixed by one or more numeric part 4185 specifiers. 4187 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part specifiers 4188 refer to the [RFC-5322] header of the message or of an encapsulated 4189 [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL message. HEADER.FIELDS 4190 and HEADER.FIELDS.NOT are followed by a list of field-name (as 4191 defined in [RFC-5322]) names, and return a subset of the header. The 4192 subset returned by HEADER.FIELDS contains only those header fields 4193 with a field-name that matches one of the names in the list; 4194 similarly, the subset returned by HEADER.FIELDS.NOT contains only the 4195 header fields with a non-matching field-name. The field-matching is 4196 ASCII range case-insensitive but otherwise exact. Subsetting does 4197 not exclude the [RFC-5322] delimiting blank line between the header 4198 and the body; the blank line is included in all header fetches, 4199 except in the case of a message which has no body and no blank line. 4201 The MIME part specifier refers to the [MIME-IMB] header for this 4202 part. 4204 The TEXT part specifier refers to the text body of the message, 4205 omitting the [RFC-5322] header. 4207 Here is an example of a complex message with some of its part 4208 specifiers: 4210 HEADER ([RFC-5322] header of the message) 4211 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4212 1 TEXT/PLAIN 4213 2 APPLICATION/OCTET-STREAM 4214 3 MESSAGE/RFC822 4215 3.HEADER ([RFC-5322] header of the message) 4216 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4217 3.1 TEXT/PLAIN 4218 3.2 APPLICATION/OCTET-STREAM 4219 4 MULTIPART/MIXED 4220 4.1 IMAGE/GIF 4221 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4222 4.2 MESSAGE/RFC822 4223 4.2.HEADER ([RFC-5322] header of the message) 4224 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4225 4.2.1 TEXT/PLAIN 4226 4.2.2 MULTIPART/ALTERNATIVE 4227 4.2.2.1 TEXT/PLAIN 4228 4.2.2.2 TEXT/RICHTEXT 4230 6.4.6. STORE Command 4232 Arguments: sequence set 4233 message data item name 4234 value for message data item 4236 Responses: untagged responses: FETCH 4238 Result: OK - store completed 4239 NO - store error: can't store that data 4240 BAD - command unknown or arguments invalid 4242 The STORE command alters data associated with a message in the 4243 mailbox. Normally, STORE will return the updated value of the data 4244 with an untagged FETCH response. A suffix of ".SILENT" in the data 4245 item name prevents the untagged FETCH, and the server SHOULD assume 4246 that the client has determined the updated value itself or does not 4247 care about the updated value. 4249 Note: Regardless of whether or not the ".SILENT" suffix was used, 4250 the server SHOULD send an untagged FETCH response if a change to a 4251 message's flags from an external source is observed. The intent 4252 is that the status of the flags is determinate without a race 4253 condition. 4255 The currently defined data items that can be stored are: 4257 FLAGS Replace the flags for the message with the 4258 argument. The new value of the flags is returned as if a FETCH of 4259 those flags was done. 4261 FLAGS.SILENT Equivalent to FLAGS, but without returning 4262 a new value. 4264 +FLAGS Add the argument to the flags for the message. 4265 The new value of the flags is returned as if a FETCH of those 4266 flags was done. 4268 +FLAGS.SILENT Equivalent to +FLAGS, but without 4269 returning a new value. 4271 -FLAGS Remove the argument from the flags for the 4272 message. The new value of the flags is returned as if a FETCH of 4273 those flags was done. 4275 -FLAGS.SILENT Equivalent to -FLAGS, but without 4276 returning a new value. 4278 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4279 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4280 S: * 3 FETCH (FLAGS (\Deleted)) 4281 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4282 S: A003 OK STORE completed 4284 6.4.7. COPY Command 4286 Arguments: sequence set 4287 mailbox name 4289 Responses: no specific responses for this command 4291 Result: OK - copy completed 4292 NO - copy error: can't copy those messages or to that 4293 name 4294 BAD - command unknown or arguments invalid 4296 The COPY command copies the specified message(s) to the end of the 4297 specified destination mailbox. The flags and internal date of the 4298 message(s) SHOULD be preserved in the copy. 4300 If the destination mailbox does not exist, a server SHOULD return an 4301 error. It SHOULD NOT automatically create the mailbox. Unless it is 4302 certain that the destination mailbox can not be created, the server 4303 MUST send the response code "[TRYCREATE]" as the prefix of the text 4304 of the tagged NO response. This gives a hint to the client that it 4305 can attempt a CREATE command and retry the COPY if the CREATE is 4306 successful. 4308 If the COPY command is unsuccessful for any reason, server 4309 implementations MUST restore the destination mailbox to its state 4310 before the COPY attempt. 4312 On successful completion of a COPY, the server SHOULD return a 4313 COPYUID response code (see Section 7.1). 4315 In the case of a mailbox that has permissions set so that the client 4316 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4317 SHOULD NOT send an COPYUID response code as it would disclose 4318 information about the mailbox. 4320 In the case of a mailbox that has UIDNOTSTICKY status (see 4321 Section 7.1), the server MAY omit the COPYUID response code as it is 4322 not meaningful. 4324 If the server does not return the COPYUID response code, the client 4325 can discover this information by selecting the destination mailbox. 4327 The location of messages placed in the destination mailbox by COPY 4328 can be determined by using FETCH and/or SEARCH commands (e.g., for 4329 Message-ID). 4331 Example: C: A003 COPY 2:4 MEETING 4332 S: A003 OK COPY completed 4334 6.4.8. MOVE Command 4336 Arguments: sequence set 4337 mailbox name 4339 Responses: no specific responses for this command 4341 Result: OK - move completed 4342 NO - move error: can't move those messages or to that 4343 name 4344 BAD - command unknown or arguments invalid 4346 The MOVE command moves the specified message(s) to the end of the 4347 specified destination mailbox. The flags and internal date of the 4348 message(s) SHOULD be preserved. 4350 This means that a new message is created in the target mailbox with a 4351 new UID, the original message is removed from the source mailbox, and 4352 it appears to the client as a single action. This has the same 4353 effect for each message as this sequence: 4355 1. [UID] COPY 4357 2. [UID] STORE +FLAGS.SILENT \DELETED 4359 3. UID EXPUNGE 4361 Although the effect of the MOVE is the same as the preceding steps, 4362 the semantics are not identical: The intermediate states produced by 4363 those steps do not occur, and the response codes are different. In 4364 particular, though the COPY and EXPUNGE response codes will be 4365 returned, response codes for a STORE MUST NOT be generated and the 4366 \Deleted flag MUST NOT be set for any message. 4368 Because a MOVE applies to a set of messages, it might fail partway 4369 through the set. Regardless of whether the command is successful in 4370 moving the entire set, each individual message SHOULD either be moved 4371 or unaffected. The server MUST leave each message in a state where 4372 it is in at least one of the source or target mailboxes (no message 4373 can be lost or orphaned). The server SHOULD NOT leave any message in 4374 both mailboxes (it would be bad for a partial failure to result in a 4375 bunch of duplicate messages). This is true even if the server 4376 returns a tagged NO response to the command. 4378 Because of the similarity of MOVE to COPY, extensions that affect 4379 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4380 (see Section 7.1), as well as those defined by extensions, are sent 4381 as appropriate. 4383 Servers SHOULD send COPYUID in response to a UID MOVE (see 4384 Section 6.4.9) command. For additional information see Section 7.1. 4386 Servers are also advised to send the COPYUID response code in an 4387 untagged OK before sending EXPUNGE or moved responses. (Sending 4388 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4389 means that clients first receive an EXPUNGE for a message and 4390 afterwards COPYUID for the same message. It can be unnecessarily 4391 difficult to process that sequence usefully.) 4393 An example: 4394 C: a UID MOVE 42:69 foo 4395 S: * OK [COPYUID 432432 42:69 1202:1229] 4396 S: * 22 EXPUNGE 4397 S: (more expunges) 4398 S: a OK Done 4400 Note that the server may send unrelated EXPUNGE responses as well, if 4401 any happen to have been expunged at the same time; this is normal 4402 IMAP operation. 4404 Note that moving a message to the currently selected mailbox (that 4405 is, where the source and target mailboxes are the same) is allowed 4406 when copying the message to the currently selected mailbox is 4407 allowed. 4409 The server may send EXPUNGE responses before the tagged response, so 4410 the client cannot safely send more commands with message sequence 4411 number arguments while the server is processing MOVE. 4413 MOVE and UID MOVE can be pipelined with other commands, but care has 4414 to be taken. Both commands modify sequence numbers and also allow 4415 unrelated EXPUNGE responses. The renumbering of other messages in 4416 the source mailbox following any EXPUNGE response can be surprising 4417 and makes it unsafe to pipeline any command that relies on message 4418 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4419 pipelined with a command that might cause message renumbering. See 4420 Section 5.5, for more information about ambiguities as well as 4421 handling requirements for both clients and servers. 4423 6.4.9. UID Command 4425 Arguments: command name 4426 command arguments 4428 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4430 Result: OK - UID command completed 4431 NO - UID command error 4432 BAD - command unknown or arguments invalid 4434 The UID command has three forms. In the first form, it takes as its 4435 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4436 appropriate for the associated command. However, the numbers in the 4437 sequence set argument are unique identifiers instead of message 4438 sequence numbers. Sequence set ranges are permitted, but there is no 4439 guarantee that unique identifiers will be contiguous. 4441 A non-existent unique identifier is ignored without any error message 4442 generated. Thus, it is possible for a UID FETCH command to return an 4443 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4444 OK without performing any operations. 4446 In the second form, the UID command takes an EXPUNGE command with an 4447 extra parameter the specified a sequence set of UIDs to operate on. 4448 The UID EXPUNGE command permanently removes all messages that both 4449 have the \Deleted flag set and have a UID that is included in the 4450 specified sequence set from the currently selected mailbox. If a 4451 message either does not have the \Deleted flag set or has a UID that 4452 is not included in the specified sequence set, it is not affected. 4454 UID EXPUNGE is particularly useful for disconnected use clients. 4455 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4456 the server, the client can ensure that it does not inadvertantly 4457 remove any messages that have been marked as \Deleted by other 4458 clients between the time that the client was last connected and 4459 the time the client resynchronizes. 4461 Example: C: A003 UID EXPUNGE 3000:3002 4462 S: * 3 EXPUNGE 4463 S: * 3 EXPUNGE 4464 S: * 3 EXPUNGE 4465 S: A003 OK UID EXPUNGE completed 4467 In the third form, the UID command takes a SEARCH command with SEARCH 4468 command arguments. The interpretation of the arguments is the same 4469 as with SEARCH; however, the numbers returned in a ESEARCH response 4470 for a UID SEARCH command are unique identifiers instead of message 4471 sequence numbers. Also, the corresponding ESEARCH response MUST 4472 include the UID indicator. For example, the command UID SEARCH 1:100 4473 UID 443:557 returns the unique identifiers corresponding to the 4474 intersection of two sequence sets, the message sequence number range 4475 1:100 and the UID range 443:557. 4477 Note: in the above example, the UID range 443:557 appears. The 4478 same comment about a non-existent unique identifier being ignored 4479 without any error message also applies here. Hence, even if 4480 neither UID 443 or 557 exist, this range is valid and would 4481 include an existing UID 495. 4483 Also note that a UID range of 559:* always includes the UID of the 4484 last message in the mailbox, even if 559 is higher than any 4485 assigned UID value. This is because the contents of a range are 4486 independent of the order of the range endpoints. Thus, any UID 4487 range with * as one of the endpoints indicates at least one 4488 message (the message with the highest numbered UID), unless the 4489 mailbox is empty. 4491 The number after the "*" in an untagged FETCH or EXPUNGE response is 4492 always a message sequence number, not a unique identifier, even for a 4493 UID command response. However, server implementations MUST 4494 implicitly include the UID message data item as part of any FETCH 4495 response caused by a UID command, regardless of whether a UID was 4496 specified as a message data item to the FETCH. 4498 Note: The rule about including the UID message data item as part of a 4499 FETCH response primarily applies to the UID FETCH and UID STORE 4500 commands, including a UID FETCH command that does not include UID as 4501 a message data item. Although it is unlikely that the other UID 4502 commands will cause an untagged FETCH, this rule applies to these 4503 commands as well. 4505 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4506 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4507 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4508 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4509 S: A999 OK UID FETCH completed 4511 6.5. Client Commands - Experimental/Expansion 4513 6.5.1. X Command 4515 Arguments: implementation defined 4517 Responses: implementation defined 4518 Result: OK - command completed 4519 NO - failure 4520 BAD - command unknown or arguments invalid 4522 Any command prefixed with an X is an experimental command. Commands 4523 which are not part of this specification, a standard or standards- 4524 track revision of this specification, or an IESG-approved 4525 experimental protocol, MUST use the X prefix. 4527 Any added untagged responses issued by an experimental command MUST 4528 also be prefixed with an X. Server implementations MUST NOT send any 4529 such untagged responses, unless the client requested it by issuing 4530 the associated experimental command. 4532 Example: C: a441 CAPABILITY 4533 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4534 S: a441 OK CAPABILITY completed 4535 C: A442 XPIG-LATIN 4536 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4537 S: A442 OK XPIG-LATIN ompleted-cay 4539 7. Server Responses 4541 Server responses are in three forms: status responses, server data, 4542 and command continuation request. The information contained in a 4543 server response, identified by "Contents:" in the response 4544 descriptions below, is described by function, not by syntax. The 4545 precise syntax of server responses is described in the Formal Syntax 4546 section. 4548 The client MUST be prepared to accept any response at all times. 4550 Status responses can be tagged or untagged. Tagged status responses 4551 indicate the completion result (OK, NO, or BAD status) of a client 4552 command, and have a tag matching the command. 4554 Some status responses, and all server data, are untagged. An 4555 untagged response is indicated by the token "*" instead of a tag. 4556 Untagged status responses indicate server greeting, or server status 4557 that does not indicate the completion of a command (for example, an 4558 impending system shutdown alert). For historical reasons, untagged 4559 server data responses are also called "unsolicited data", although 4560 strictly speaking, only unilateral server data is truly 4561 "unsolicited". 4563 Certain server data MUST be recorded by the client when it is 4564 received; this is noted in the description of that data. Such data 4565 conveys critical information which affects the interpretation of all 4566 subsequent commands and responses (e.g., updates reflecting the 4567 creation or destruction of messages). 4569 Other server data SHOULD be recorded for later reference; if the 4570 client does not need to record the data, or if recording the data has 4571 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4572 in progress), the data SHOULD be ignored. 4574 An example of unilateral untagged server data occurs when the IMAP 4575 connection is in the selected state. In the selected state, the 4576 server checks the mailbox for new messages as part of command 4577 execution. Normally, this is part of the execution of every command; 4578 hence, a NOOP command suffices to check for new messages. If new 4579 messages are found, the server sends untagged EXISTS response 4580 reflecting the new size of the mailbox. Server implementations that 4581 offer multiple simultaneous access to the same mailbox SHOULD also 4582 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4583 another agent changes the state of any message flags or expunges any 4584 messages. 4586 Command continuation request responses use the token "+" instead of a 4587 tag. These responses are sent by the server to indicate acceptance 4588 of an incomplete client command and readiness for the remainder of 4589 the command. 4591 7.1. Server Responses - Status Responses 4593 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4594 can be tagged or untagged. PREAUTH and BYE are always untagged. 4596 Status responses MAY include an OPTIONAL "response code". A response 4597 code consists of data inside square brackets in the form of an atom, 4598 possibly followed by a space and arguments. The response code 4599 contains additional information or status codes for client software 4600 beyond the OK/NO/BAD condition, and are defined when there is a 4601 specific action that a client can take based upon the additional 4602 information. 4604 The currently defined response codes are: 4606 ALERT 4608 The human-readable text contains a special alert that MUST be 4609 presented to the user in a fashion that calls the user's 4610 attention to the message. 4612 ALREADYEXISTS 4613 The operation attempts to create something that already exists, 4614 such as when the CREATE or RENAME directories attempt to create 4615 a mailbox and there is already one of that name. 4617 C: o356 RENAME this that 4618 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4620 APPENDUID 4622 Followed by the UIDVALIDITY of the destination mailbox and the 4623 UID assigned to the appended message in the destination 4624 mailbox, indicates that the message has been appended to the 4625 destination mailbox with that UID. 4627 If the server also supports the [MULTIAPPEND] extension, and if 4628 multiple messages were appended in the APPEND command, then the 4629 second value is a UID set containing the UIDs assigned to the 4630 appended messages, in the order they were transmitted in the 4631 APPEND command. This UID set may not contain extraneous UIDs 4632 or the symbol "*". 4634 Note: the UID set form of the APPENDUID response code MUST 4635 NOT be used if only a single message was appended. In 4636 particular, a server MUST NOT send a range such as 123:123. 4637 This is because a client that does not support [MULTIAPPEND] 4638 expects only a single UID and not a UID set. 4640 UIDs are assigned in strictly ascending order in the mailbox 4641 (refer to Section 2.3.1.1); note that a range of 12:10 is 4642 exactly equivalent to 10:12 and refers to the sequence 4643 10,11,12. 4645 This response code is returned in a tagged OK response to the 4646 APPEND command. 4648 AUTHENTICATIONFAILED 4650 Authentication failed for some reason on which the server is 4651 unwilling to elaborate. Typically, this includes "unknown 4652 user" and "bad password". 4654 This is the same as not sending any response code, except that 4655 when a client sees AUTHENTICATIONFAILED, it knows that the 4656 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4657 trying the same login/password again later. 4659 C: b LOGIN "fred" "foo" 4660 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4662 AUTHORIZATIONFAILED 4664 Authentication succeeded in using the authentication identity, 4665 but the server cannot or will not allow the authentication 4666 identity to act as the requested authorization identity. This 4667 is only applicable when the authentication and authorization 4668 identities are different. 4670 C: c1 AUTHENTICATE PLAIN 4671 [...] 4672 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4674 C: c2 AUTHENTICATE PLAIN 4675 [...] 4676 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4678 BADCHARSET 4680 Optionally followed by a parenthesized list of charsets. A 4681 SEARCH failed because the given charset is not supported by 4682 this implementation. If the optional list of charsets is 4683 given, this lists the charsets that are supported by this 4684 implementation. 4686 CANNOT 4688 The operation violates some invariant of the server and can 4689 never succeed. 4691 C: l create "///////" 4692 S: l NO [CANNOT] Adjacent slashes are not supported 4694 CAPABILITY 4696 Followed by a list of capabilities. This can appear in the 4697 initial OK or PREAUTH response to transmit an initial 4698 capabilities list. It can also appear in tagged responses to 4699 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4700 a client to send a separate CAPABILITY command if it recognizes 4701 this response. 4703 CLIENTBUG 4704 The server has detected a client bug. This can accompany all 4705 of OK, NO, and BAD, depending on what the client bug is. 4707 C: k1 select "/archive/projects/experiment-iv" 4708 [...] 4709 S: k1 OK [READ-ONLY] Done 4710 C: k2 status "/archive/projects/experiment-iv" (messages) 4711 [...] 4712 S: k2 OK [CLIENTBUG] Done 4714 CLOSED 4716 The CLOSED response code has no parameters. A server return 4717 the CLOSED response code when the currently selected mailbox is 4718 closed implicitly using the SELECT/EXAMINE command on another 4719 mailbox. The CLOSED response code serves as a boundary between 4720 responses for the previously opened mailbox (which was closed) 4721 and the newly selected mailbox; all responses before the CLOSED 4722 response code relate to the mailbox that was closed, and all 4723 subsequent responses relate to the newly opened mailbox. 4725 There is no need to return the CLOSED response code on 4726 completion of the CLOSE or the UNSELECT command (or similar), 4727 whose purpose is to close the currently selected mailbox 4728 without opening a new one. 4730 CONTACTADMIN 4732 The user should contact the system administrator or support 4733 desk. 4735 C: e login "fred" "foo" 4736 S: e NO [CONTACTADMIN] 4738 COPYUID 4740 Followed by the UIDVALIDITY of the destination mailbox, a UID 4741 set containing the UIDs of the message(s) in the source mailbox 4742 that were copied to the destination mailbox and containing the 4743 UIDs assigned to the copied message(s) in the destination 4744 mailbox, indicates that the message(s) have been copied to the 4745 destination mailbox with the stated UID(s). 4747 The source UID set is in the order the message(s) were copied; 4748 the destination UID set corresponds to the source UID set and 4749 is in the same order. Neither of the UID sets may contain 4750 extraneous UIDs or the symbol "*". 4752 UIDs are assigned in strictly ascending order in the mailbox 4753 (refer to Section 2.3.1.1); note that a range of 12:10 is 4754 exactly equivalent to 10:12 and refers to the sequence 4755 10,11,12. 4757 This response code is returned in a tagged OK response to the 4758 COPY command. 4760 CORRUPTION 4762 The server discovered that some relevant data (e.g., the 4763 mailbox) are corrupt. This response code does not include any 4764 information about what's corrupt, but the server can write that 4765 to its logfiles. 4767 C: i select "/archive/projects/experiment-iv" 4768 S: i NO [CORRUPTION] Cannot open mailbox 4770 EXPIRED 4772 Either authentication succeeded or the server no longer had the 4773 necessary data; either way, access is no longer permitted using 4774 that passphrase. The client or user should get a new 4775 passphrase. 4777 C: d login "fred" "foo" 4778 S: d NO [EXPIRED] That password isn't valid any more 4780 EXPUNGEISSUED 4782 Someone else has issued an EXPUNGE for the same mailbox. The 4783 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4784 discusses this subject in depth. 4786 C: h search from fred@example.com 4787 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4788 S: h OK [EXPUNGEISSUED] Search completed 4790 HASCHILDREN 4792 The mailbox delete operation failed because the mailbox has one 4793 or more children and the server doesn't allow deletion of 4794 mailboxes with children. 4796 C: m356 DELETE Notes 4797 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4798 to be deleted first 4800 INUSE 4802 An operation has not been carried out because it involves 4803 sawing off a branch someone else is sitting on. Someone else 4804 may be holding an exclusive lock needed for this operation, or 4805 the operation may involve deleting a resource someone else is 4806 using, typically a mailbox. 4808 The operation may succeed if the client tries again later. 4810 C: g delete "/archive/projects/experiment-iv" 4811 S: g NO [INUSE] Mailbox in use 4813 LIMIT 4815 The operation ran up against an implementation limit of some 4816 kind, such as the number of flags on a single message or the 4817 number of flags used in a mailbox. 4819 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4820 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4822 NONEXISTENT 4824 The operation attempts to delete something that does not exist. 4825 Similar to ALREADYEXISTS. 4827 C: p RENAME this that 4828 S: p NO [NONEXISTENT] No such mailbox 4830 NOPERM 4832 The access control system (e.g., Access Control List (ACL), see 4833 [RFC4314] does not permit this user to carry out an operation, 4834 such as selecting or creating a mailbox. 4836 C: f select "/archive/projects/experiment-iv" 4837 S: f NO [NOPERM] Access denied 4839 OVERQUOTA 4841 The user would be over quota after the operation. (The user 4842 may or may not be over quota already.) 4844 Note that if the server sends OVERQUOTA but doesn't support the 4845 IMAP QUOTA extension defined by [RFC2087], then there is a 4846 quota, but the client cannot find out what the quota is. 4848 C: n1 uid copy 1:* oldmail 4849 S: n1 NO [OVERQUOTA] Sorry 4851 C: n2 uid copy 1:* oldmail 4852 S: n2 OK [OVERQUOTA] You are now over your soft quota 4854 PARSE 4856 The human-readable text represents an error in parsing the 4857 [RFC-5322] header or [MIME-IMB] headers of a message in the 4858 mailbox. 4860 PERMANENTFLAGS 4862 Followed by a parenthesized list of flags, indicates which of 4863 the known flags the client can change permanently. Any flags 4864 that are in the FLAGS untagged response, but not the 4865 PERMANENTFLAGS list, can not be set permanently. The 4866 PERMANENTFLAGS list can also include the special flag \*, which 4867 indicates that it is possible to create new keywords by 4868 attempting to store those keywords in the mailbox. If the 4869 client attempts to STORE a flag that is not in the 4870 PERMANENTFLAGS list, the server will either ignore the change 4871 or store the state change for the remainder of the current 4872 session only. 4874 There is no need for a server that included the special flag \* 4875 to return a new PERMANENTFLAGS response code when a new keyword 4876 was successfully set on a message upon client request. However 4877 if the server has a limit on the number of different keywords 4878 that can be stored in a mailbox and that limit is reached, the 4879 server MUST send a new PERMANENTFLAGS response code without the 4880 special flag \*. 4882 PRIVACYREQUIRED 4884 The operation is not permitted due to a lack of privacy. If 4885 Transport Layer Security (TLS) is not in use, the client could 4886 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4888 C: d login "fred" "foo" 4889 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4891 C: d select inbox 4892 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4894 READ-ONLY 4896 The mailbox is selected read-only, or its access while selected 4897 has changed from read-write to read-only. 4899 READ-WRITE 4901 The mailbox is selected read-write, or its access while 4902 selected has changed from read-only to read-write. 4904 SERVERBUG 4906 The server encountered a bug in itself or violated one of its 4907 own invariants. 4909 C: j select "/archive/projects/experiment-iv" 4910 S: j NO [SERVERBUG] This should not happen 4912 TRYCREATE 4914 An APPEND or COPY attempt is failing because the target mailbox 4915 does not exist (as opposed to some other reason). This is a 4916 hint to the client that the operation can succeed if the 4917 mailbox is first created by the CREATE command. 4919 UIDNEXT 4921 Followed by a decimal number, indicates the next unique 4922 identifier value. Refer to Section 2.3.1.1 for more 4923 information. 4925 UIDNOTSTICKY 4927 The selected mailbox is supported by a mail store that does not 4928 support persistent UIDs; that is, UIDVALIDITY will be different 4929 each time the mailbox is selected. Consequently, APPEND or 4930 COPY to this mailbox will not return an APPENDUID or COPYUID 4931 response code. 4933 This response code is returned in an untagged NO response to 4934 the SELECT command. 4936 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4937 This facility exists to support legacy mail stores in which 4938 it is technically infeasible to support persistent UIDs. 4939 This should be avoided when designing new mail stores. 4941 UIDVALIDITY 4943 Followed by a decimal number, indicates the unique identifier 4944 validity value. Refer to Section 2.3.1.1 for more information. 4946 UNAVAILABLE 4948 Temporary failure because a subsystem is down. For example, an 4949 IMAP server that uses a Lightweight Directory Access Protocol 4950 (LDAP) or Radius server for authentication might use this 4951 response code when the LDAP/Radius server is down. 4953 C: a LOGIN "fred" "foo" 4954 S: a NO [UNAVAILABLE] User's backend down for maintenance 4956 UNKNOWN-CTE 4958 The server does not know how to decode the section's Content- 4959 Transfer-Encoding. 4961 Client implementations MUST ignore response codes that they do not 4962 recognize. 4964 7.1.1. OK Response 4966 Contents: OPTIONAL response code 4967 human-readable text 4969 The OK response indicates an information message from the server. 4970 When tagged, it indicates successful completion of the associated 4971 command. The human-readable text MAY be presented to the user as an 4972 information message. The untagged form indicates an information-only 4973 message; the nature of the information MAY be indicated by a response 4974 code. 4976 The untagged form is also used as one of three possible greetings at 4977 connection startup. It indicates that the connection is not yet 4978 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4980 Example: S: * OK IMAP4rev2 server ready 4981 C: A001 LOGIN fred blurdybloop 4982 S: * OK [ALERT] System shutdown in 10 minutes 4983 S: A001 OK LOGIN Completed 4985 7.1.2. NO Response 4987 Contents: OPTIONAL response code 4988 human-readable text 4990 The NO response indicates an operational error message from the 4991 server. When tagged, it indicates unsuccessful completion of the 4992 associated command. The untagged form indicates a warning; the 4993 command can still complete successfully. The human-readable text 4994 describes the condition. 4996 Example: C: A222 COPY 1:2 owatagusiam 4997 S: * NO Disk is 98% full, please delete unnecessary data 4998 S: A222 OK COPY completed 4999 C: A223 COPY 3:200 blurdybloop 5000 S: * NO Disk is 98% full, please delete unnecessary data 5001 S: * NO Disk is 99% full, please delete unnecessary data 5002 S: A223 NO COPY failed: disk is full 5004 7.1.3. BAD Response 5006 Contents: OPTIONAL response code 5007 human-readable text 5009 The BAD response indicates an error message from the server. When 5010 tagged, it reports a protocol-level error in the client's command; 5011 the tag indicates the command that caused the error. The untagged 5012 form indicates a protocol-level error for which the associated 5013 command can not be determined; it can also indicate an internal 5014 server failure. The human-readable text describes the condition. 5016 Example: C: ...very long command line... 5017 S: * BAD Command line too long 5018 C: ...empty line... 5019 S: * BAD Empty command line 5020 C: A443 EXPUNGE 5021 S: * BAD Disk crash, attempting salvage to a new disk! 5022 S: * OK Salvage successful, no data lost 5023 S: A443 OK Expunge completed 5025 7.1.4. PREAUTH Response 5027 Contents: OPTIONAL response code 5028 human-readable text 5030 The PREAUTH response is always untagged, and is one of three possible 5031 greetings at connection startup. It indicates that the connection 5032 has already been authenticated by external means; thus no LOGIN/ 5033 AUTHENTICATE command is needed. 5035 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 5037 7.1.5. BYE Response 5039 Contents: OPTIONAL response code 5040 human-readable text 5042 The BYE response is always untagged, and indicates that the server is 5043 about to close the connection. The human-readable text MAY be 5044 displayed to the user in a status report by the client. The BYE 5045 response is sent under one of four conditions: 5047 1. as part of a normal logout sequence. The server will close the 5048 connection after sending the tagged OK response to the LOGOUT 5049 command. 5051 2. as a panic shutdown announcement. The server closes the 5052 connection immediately. 5054 3. as an announcement of an inactivity autologout. The server 5055 closes the connection immediately. 5057 4. as one of three possible greetings at connection startup, 5058 indicating that the server is not willing to accept a connection 5059 from this client. The server closes the connection immediately. 5061 The difference between a BYE that occurs as part of a normal LOGOUT 5062 sequence (the first case) and a BYE that occurs because of a failure 5063 (the other three cases) is that the connection closes immediately in 5064 the failure case. In all cases the client SHOULD continue to read 5065 response data from the server until the connection is closed; this 5066 will ensure that any pending untagged or completion responses are 5067 read and processed. 5069 Example: S: * BYE Autologout; idle for too long 5071 7.2. Server Responses - Server and Mailbox Status 5073 These responses are always untagged. This is how server and mailbox 5074 status data are transmitted from the server to the client. Many of 5075 these responses typically result from a command with the same name. 5077 7.2.1. The ENABLED Response 5079 Contents: capability listing 5081 The ENABLED response occurs as a result of an ENABLE command. The 5082 capability listing contains a space-separated listing of capability 5083 names that the server supports and that were successfully enabled. 5084 The ENABLED response may contain no capabilities, which means that no 5085 extensions listed by the client were successfully enabled. 5087 7.2.2. CAPABILITY Response 5089 Contents: capability listing 5091 The CAPABILITY response occurs as a result of a CAPABILITY command. 5092 The capability listing contains a space-separated listing of 5093 capability names that the server supports. The capability listing 5094 MUST include the atom "IMAP4rev2". 5096 In addition, client and server implementations MUST implement the 5097 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 5098 capabilities. See the Security Considerations section for important 5099 information. 5101 A capability name which begins with "AUTH=" indicates that the server 5102 supports that particular authentication mechanism. 5104 The LOGINDISABLED capability indicates that the LOGIN command is 5105 disabled, and that the server will respond with a tagged NO response 5106 to any attempt to use the LOGIN command even if the user name and 5107 password are valid. An IMAP client MUST NOT issue the LOGIN command 5108 if the server advertises the LOGINDISABLED capability. 5110 Other capability names indicate that the server supports an 5111 extension, revision, or amendment to the IMAP4rev2 protocol. Server 5112 responses MUST conform to this document until the client issues a 5113 command that uses the associated capability. 5115 Capability names MUST either begin with "X" or be informational, 5116 experimental or standards-track IMAP4rev2 extensions, revisions, or 5117 amendments registered with IANA. A server SHOULD NOT offer 5118 unregistered or non-standard capability names, unless such names are 5119 prefixed with an "X". 5121 Client implementations SHOULD NOT require any capability name other 5122 than "IMAP4rev2", and MUST ignore any unknown capability names. 5124 A server MAY send capabilities automatically, by using the CAPABILITY 5125 response code in the initial PREAUTH or OK responses, and by sending 5126 an updated CAPABILITY response code in the tagged OK response as part 5127 of a successful authentication. It is unnecessary for a client to 5128 send a separate CAPABILITY command if it recognizes these automatic 5129 capabilities. 5131 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 5133 7.2.3. LIST Response 5135 Contents: name attributes 5136 hierarchy delimiter 5137 name 5138 OPTIONAL extension data 5140 The LIST response occurs as a result of a LIST command. It returns a 5141 single name that matches the LIST specification. There can be 5142 multiple LIST responses for a single LIST command. 5144 The following base mailbox name attributes are defined: 5146 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5147 name does not refer to an existing mailbox. Note that this 5148 attribute is not meaningful by itself, as mailbox names that match 5149 the canonical LIST pattern but don't exist must not be returned 5150 unless one of the two conditions listed below is also satisfied: 5152 1. The mailbox name also satisfies the selection criteria (for 5153 example, it is subscribed and the "SUBSCRIBED" selection 5154 option has been specified). 5156 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5157 at least one descendant mailbox name that does not match the 5158 LIST pattern and does match the selection criteria. 5160 In practice, this means that the "\NonExistent" attribute is 5161 usually returned with one or more of "\Subscribed", "\Remote", 5162 "\HasChildren", or the CHILDINFO extended data item. 5164 The "\NonExistent" attribute implies "\NoSelect". 5166 \Noinferiors It is not possible for any child levels of hierarchy to 5167 exist under this name; no child levels exist now and none can be 5168 created in the future. 5170 \Noselect It is not possible to use this name as a selectable 5171 mailbox. 5173 \HasChildren The presence of this attribute indicates that the 5174 mailbox has child mailboxes. A server SHOULD NOT set this 5175 attribute if there are child mailboxes and the user does not have 5176 permission to access any of them. In this case, \HasNoChildren 5177 SHOULD be used. In many cases, however, a server may not be able 5178 to efficiently compute whether a user has access to any child 5179 mailbox. Note that even though the \HasChildren attribute for a 5180 mailbox must be correct at the time of processing of the mailbox, 5181 a client must be prepared to deal with a situation when a mailbox 5182 is marked with the \HasChildren attribute, but no child mailbox 5183 appears in the response to the LIST command. This might happen, 5184 for example, due to children mailboxes being deleted or made 5185 inaccessible to the user (using access control) by another client 5186 before the server is able to list them. 5188 \HasNoChildren The presence of this attribute indicates that the 5189 mailbox has NO child mailboxes that are accessible to the 5190 currently authenticated user. 5192 \Marked The mailbox has been marked "interesting" by the server; the 5193 mailbox probably contains messages that have been added since the 5194 last time the mailbox was selected. 5196 \Unmarked The mailbox does not contain any additional messages since 5197 the last time the mailbox was selected. 5199 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5200 command. 5202 \Remote The mailbox is a remote mailbox. 5204 It is an error for the server to return both a \HasChildren and a 5205 \HasNoChildren attribute in the same LIST response. A client that 5206 encounters a LIST response with both \HasChildren and \HasNoChildren 5207 attributes present should act as if both are absent in the LIST 5208 response. 5210 Note: the \HasNoChildren attribute should not be confused with the 5211 \NoInferiors attribute, which indicates that no child mailboxes 5212 exist now and none can be created in the future. 5214 If it is not feasible for the server to determine whether or not the 5215 mailbox is "interesting", the server SHOULD NOT send either \Marked 5216 or \Unmarked. The server MUST NOT send more than one of \Marked, 5217 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5218 these. 5220 In addition to the base mailbox name attributes defined above, an 5221 IMAP server MAY also include any or all of the following attributes 5222 that denote "role" (or "special-use") of a mailbox. These attributes 5223 are included along with base attributes defined above. A given 5224 mailbox may have none, one, or more than one of these attributes. In 5225 some cases, a special use is advice to a client about what to put in 5226 that mailbox. In other cases, it's advice to a client about what to 5227 expect to find there. 5229 \All This mailbox presents all messages in the user's message store. 5230 Implementations MAY omit some messages, such as, perhaps, those in 5231 \Trash and \Junk. When this special use is supported, it is 5232 almost certain to represent a virtual mailbox. 5234 \Archive This mailbox is used to archive messages. The meaning of 5235 an "archival" mailbox is server-dependent; typically, it will be 5236 used to get messages out of the inbox, or otherwise keep them out 5237 of the user's way, while still making them accessible. 5239 \Drafts This mailbox is used to hold draft messages -- typically, 5240 messages that are being composed but have not yet been sent. In 5241 some server implementations, this might be a virtual mailbox, 5242 containing messages from other mailboxes that are marked with the 5243 "\Draft" message flag. Alternatively, this might just be advice 5244 that a client put drafts here. 5246 \Flagged This mailbox presents all messages marked in some way as 5247 "important". When this special use is supported, it is likely to 5248 represent a virtual mailbox collecting messages (from other 5249 mailboxes) that are marked with the "\Flagged" message flag. 5251 \Junk This mailbox is where messages deemed to be junk mail are 5252 held. Some server implementations might put messages here 5253 automatically. Alternatively, this might just be advice to a 5254 client-side spam filter. 5256 \Sent This mailbox is used to hold copies of messages that have been 5257 sent. Some server implementations might put messages here 5258 automatically. Alternatively, this might just be advice that a 5259 client save sent messages here. 5261 \Trash This mailbox is used to hold messages that have been deleted 5262 or marked for deletion. In some server implementations, this 5263 might be a virtual mailbox, containing messages from other 5264 mailboxes that are marked with the "\Deleted" message flag. 5265 Alternatively, this might just be advice that a client that 5266 chooses not to use the IMAP "\Deleted" model should use this as 5267 its trash location. In server implementations that strictly 5268 expect the IMAP "\Deleted" model, this special use is likely not 5269 to be supported. 5271 All of special-use attributes are OPTIONAL, and any given server or 5272 message store may support any combination of the attributes, or none 5273 at all. In most cases, there will likely be at most one mailbox with 5274 a given attribute for a given user, but in some server or message 5275 store implementations it might be possible for multiple mailboxes to 5276 have the same special-use attribute. 5278 Special-use attributes are likely to be user-specific. User Adam 5279 might share his \Sent mailbox with user Barb, but that mailbox is 5280 unlikely to also serve as Barb's \Sent mailbox. 5282 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5283 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5285 The hierarchy delimiter is a character used to delimit levels of 5286 hierarchy in a mailbox name. A client can use it to create child 5287 mailboxes, and to search higher or lower levels of naming hierarchy. 5288 All children of a top-level hierarchy node MUST use the same 5289 separator character. A NIL hierarchy delimiter means that no 5290 hierarchy exists; the name is a "flat" name. 5292 The name represents an unambiguous left-to-right hierarchy, and MUST 5293 be valid for use as a reference in LIST command. Unless \Noselect or 5294 \NonExistent is indicated, the name MUST also be valid as an argument 5295 for commands, such as SELECT, that accept mailbox names. 5297 The name might be followed by an OPTIONAL series of extended fields, 5298 a parenthesized list of tagged data (also referred to as "extended 5299 data item"). The first element of an extended field is a string, 5300 which identifies the type of data. [RFC5258] specified requirements 5301 on string registration (which are called "tags" there; such tags are 5302 not to be confused with IMAP command tags), in particular it said 5303 that "Tags MUST be registered with IANA". This document doesn't 5304 change that. See Section 9.5 of [RFC5258] for the registration 5305 template. The server MAY return data in the extended fields that was 5306 not directly solicited by the client in the corresponding LIST 5307 command. For example, the client can enable extra extended fields by 5308 using another IMAP extension that make use of the extended LIST 5309 responses. The client MUST ignore all extended fields it doesn't 5310 recognize. 5312 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5314 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5315 ("color" "red")) Sample "text") 5316 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5317 Sample ("text" "more text")) 5319 7.2.4. NAMESPACE Response 5321 Contents: the prefix and hierarchy delimiter to the server's 5322 Personal Namespace(s), Other Users' Namespace(s), and 5323 Shared Namespace(s) 5325 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5326 contains the prefix and hierarchy delimiter to the server's Personal 5327 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5328 the server wishes to expose. The response will contain a NIL for any 5329 namespace class that is not available. Namespace-Response-Extensions 5330 ABNF non terminal is defined for extensibility and MAY be included in 5331 the response. 5333 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5335 7.2.5. STATUS Response 5337 Contents: name 5338 status parenthesized list 5340 The STATUS response occurs as a result of an STATUS command. It 5341 returns the mailbox name that matches the STATUS specification and 5342 the requested mailbox status information. 5344 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5346 7.2.6. ESEARCH Response 5348 Contents: one or more search-return-data pairs 5350 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5351 command. 5353 The ESEARCH response starts with an optional search correlator. If 5354 it is missing, then the response was not caused by a particular IMAP 5355 command, whereas if it is present, it contains the tag of the command 5356 that caused the response to be returned. 5358 The search correlator is followed by an optional UID indicator. If 5359 this indicator is present, all data in the ESEARCH response refers to 5360 UIDs, otherwise all returned data refers to message numbers. 5362 The rest of the ESEARCH response contains one or more search data 5363 pairs. Each pair starts with unique return item name, followed by a 5364 space and the corresponding data. Search data pairs may be returned 5365 in any order. Unless specified otherwise by an extension, any return 5366 item name SHOULD appear only once in an ESEARCH response. 5368 [[TBD: describe the most common search data pairs returned.]] 5370 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5372 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5374 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5376 7.2.7. FLAGS Response 5378 Contents: flag parenthesized list 5380 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5381 The flag parenthesized list identifies the flags (at a minimum, the 5382 system-defined flags) that are applicable for this mailbox. Flags 5383 other than the system flags can also exist, depending on server 5384 implementation. 5386 The update from the FLAGS response MUST be recorded by the client. 5388 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5390 7.3. Server Responses - Mailbox Size 5392 These responses are always untagged. This is how changes in the size 5393 of the mailbox are transmitted from the server to the client. 5394 Immediately following the "*" token is a number that represents a 5395 message count. 5397 7.3.1. EXISTS Response 5399 Contents: none 5401 The EXISTS response reports the number of messages in the mailbox. 5402 This response occurs as a result of a SELECT or EXAMINE command, and 5403 if the size of the mailbox changes (e.g., new messages). 5405 The update from the EXISTS response MUST be recorded by the client. 5407 Example: S: * 23 EXISTS 5409 7.4. Server Responses - Message Status 5411 These responses are always untagged. This is how message data are 5412 transmitted from the server to the client, often as a result of a 5413 command with the same name. Immediately following the "*" token is a 5414 number that represents a message sequence number. 5416 7.4.1. EXPUNGE Response 5418 Contents: none 5420 The EXPUNGE response reports that the specified message sequence 5421 number has been permanently removed from the mailbox. The message 5422 sequence number for each successive message in the mailbox is 5423 immediately decremented by 1, and this decrement is reflected in 5424 message sequence numbers in subsequent responses (including other 5425 untagged EXPUNGE responses). 5427 The EXPUNGE response also decrements the number of messages in the 5428 mailbox; it is not necessary to send an EXISTS response with the new 5429 value. 5431 As a result of the immediate decrement rule, message sequence numbers 5432 that appear in a set of successive EXPUNGE responses depend upon 5433 whether the messages are removed starting from lower numbers to 5434 higher numbers, or from higher numbers to lower numbers. For 5435 example, if the last 5 messages in a 9-message mailbox are expunged, 5436 a "lower to higher" server will send five untagged EXPUNGE responses 5437 for message sequence number 5, whereas a "higher to lower server" 5438 will send successive untagged EXPUNGE responses for message sequence 5439 numbers 9, 8, 7, 6, and 5. 5441 An EXPUNGE response MUST NOT be sent when no command is in progress, 5442 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5443 is necessary to prevent a loss of synchronization of message sequence 5444 numbers between client and server. A command is not "in progress" 5445 until the complete command has been received; in particular, a 5446 command is not "in progress" during the negotiation of command 5447 continuation. 5449 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5450 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5451 during a UID command. 5453 The update from the EXPUNGE response MUST be recorded by the client. 5455 Example: S: * 44 EXPUNGE 5457 7.4.2. FETCH Response 5459 Contents: message data 5461 The FETCH response returns data about a message to the client. The 5462 data are pairs of data item names and their values in parentheses. 5463 This response occurs as the result of a FETCH or STORE command, as 5464 well as by unilateral server decision (e.g., flag updates). 5466 The current data items are: 5468 BINARY[]<> 5470 An or expressing the content of the 5471 specified section after removing any Content-Transfer-Encoding- 5472 related encoding. If is present it refers to the 5473 offset within the DECODED section data. 5475 If the domain of the decoded data is "8bit" and the data does 5476 not contain the NUL octet, the server SHOULD return the data in 5477 a instead of a ; this allows the client to 5478 determine if the "8bit" data contains the NUL octet without 5479 having to explicitly scan the data stream for for NULs. 5481 Messaging clients and servers have been notoriously lax in 5482 their adherence to the Internet CRLF convention for terminating 5483 lines of textual data (text/* media types) in Internet 5484 protocols. When sending data in BINARY[...] FETCH data item, 5485 servers MUST ensure that textual line-oriented sections are 5486 always transmitted using the IMAP4 CRLF line termination 5487 syntax, regardless of the underlying storage representation of 5488 the data on the server. 5490 If the server does not know how to decode the section's 5491 Content-Transfer-Encoding, it MUST fail the request and issue a 5492 "NO" response that contains the "UNKNOWN-CTE" response code. 5494 BINARY.SIZE[] 5496 The size of the section after removing any Content-Transfer- 5497 Encoding-related encoding. The value returned MUST match the 5498 size of the or that will be returned by 5499 the corresponding FETCH BINARY request. 5501 If the server does not know how to decode the section's 5502 Content-Transfer-Encoding, it MUST fail the request and issue a 5503 "NO" response that contains the "UNKNOWN-CTE" response code. 5505 BODY A form of BODYSTRUCTURE without extension data. 5507 BODY[
]<> 5509 A string expressing the body contents of the specified section. 5510 The string SHOULD be interpreted by the client according to the 5511 content transfer encoding, body type, and subtype. 5513 If the origin octet is specified, this string is a substring of 5514 the entire body contents, starting at that origin octet. This 5515 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5516 truncated. 5518 Note: The origin octet facility MUST NOT be used by a server 5519 in a FETCH response unless the client specifically requested 5520 it by means of a FETCH of a BODY[
]<> data 5521 item. 5523 8-bit textual data is permitted if a [CHARSET] identifier is 5524 part of the body parameter parenthesized list for this section. 5525 Note that headers (part specifiers HEADER or MIME, or the 5526 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5527 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5528 line between the header and the body is not affected by header 5529 line subsetting; the blank line is always included as part of 5530 header data, except in the case of a message which has no body 5531 and no blank line. 5533 Non-textual data such as binary data MUST be transfer encoded 5534 into a textual form, such as BASE64, prior to being sent to the 5535 client. To derive the original binary data, the client MUST 5536 decode the transfer encoded string. 5538 BODYSTRUCTURE 5540 A parenthesized list that describes the [MIME-IMB] body 5541 structure of a message. This is computed by the server by 5542 parsing the [MIME-IMB] header fields, defaulting various fields 5543 as necessary. 5545 For example, a simple text message of 48 lines and 2279 octets 5546 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5547 ASCII") NIL NIL "7BIT" 2279 48) 5549 Multiple parts are indicated by parenthesis nesting. Instead 5550 of a body type as the first element of the parenthesized list, 5551 there is a sequence of one or more nested body structures. The 5552 second element of the parenthesized list is the multipart 5553 subtype (mixed, digest, parallel, alternative, etc.). 5555 For example, a two part message consisting of a text and a 5556 BASE64-encoded text attachment can have a body structure of: 5557 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5558 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5559 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5560 "BASE64" 4554 73) "MIXED") 5562 Extension data follows the multipart subtype. Extension data 5563 is never returned with the BODY fetch, but can be returned with 5564 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5565 the defined order. The extension data of a multipart body part 5566 are in the following order: 5568 body parameter parenthesized list A parenthesized list of 5569 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5570 "bar" is the value of "foo", and "rag" is the value of 5571 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5572 parameter value continuations and parameter value character 5573 sets as described in [RFC2231], for example, if the message 5574 contains parameters "baz*0", "baz*1" and "baz*2", the server 5575 should RFC2231-decode them, concatenate and return the 5576 resulting value as a parameter "baz". Similarly, if the 5577 message contains parameters "foo*0*" and "foo*1*", the 5578 server should RFC2231-decode them, convert to UTF-8, 5579 concatenate and return the resulting value as a parameter 5580 "foo*". 5582 body disposition A parenthesized list, consisting of a 5583 disposition type string, followed by a parenthesized list of 5584 disposition attribute/value pairs as defined in 5585 [DISPOSITION]. Servers SHOULD decode parameter value 5586 continuations as described in [RFC2231]. 5588 body language A string or parenthesized list giving the body 5589 language value as defined in [LANGUAGE-TAGS]. 5591 body location A string giving the body content URI as defined 5592 in [LOCATION]. 5594 Any following extension data are not yet defined in this 5595 version of the protocol. Such extension data can consist of 5596 zero or more NILs, strings, numbers, or potentially nested 5597 parenthesized lists of such data. Client implementations that 5598 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5599 extension data. Server implementations MUST NOT send such 5600 extension data until it has been defined by a revision of this 5601 protocol. 5603 The basic fields of a non-multipart body part are in the 5604 following order: 5606 body type A string giving the content media type name as 5607 defined in [MIME-IMB]. 5609 body subtype A string giving the content subtype name as 5610 defined in [MIME-IMB]. 5612 body parameter parenthesized list A parenthesized list of 5613 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5614 "bar" is the value of "foo" and "rag" is the value of "baz"] 5615 as defined in [MIME-IMB]. 5617 body id A string giving the Content-ID header field value as 5618 defined in Section 7 of [MIME-IMB]. 5620 body description A string giving the Content-Description 5621 header field value as defined in Section 8 of [MIME-IMB]. 5623 body encoding A string giving the content transfer encoding as 5624 defined in Section 6 of [MIME-IMB]. 5626 body size A number giving the size of the body in octets. 5627 Note that this size is the size in its transfer encoding and 5628 not the resulting size after any decoding. 5630 A body type of type MESSAGE and subtype RFC822 contains, 5631 immediately after the basic fields, the envelope structure, 5632 body structure, and size in text lines of the encapsulated 5633 message. 5635 A body type of type TEXT contains, immediately after the basic 5636 fields, the size of the body in text lines. Note that this 5637 size is the size in its content transfer encoding and not the 5638 resulting size after any decoding. 5640 Extension data follows the basic fields and the type-specific 5641 fields listed above. Extension data is never returned with the 5642 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5643 Extension data, if present, MUST be in the defined order. 5645 The extension data of a non-multipart body part are in the 5646 following order: 5648 body MD5 A string giving the body MD5 value as defined in 5649 [MD5]. 5651 body disposition A parenthesized list with the same content 5652 and function as the body disposition for a multipart body 5653 part. 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, and would be as described above under 5663 multipart extension data. 5665 ENVELOPE 5667 A parenthesized list that describes the envelope structure of a 5668 message. This is computed by the server by parsing the 5669 [RFC-5322] header into the component parts, defaulting various 5670 fields as necessary. 5672 The fields of the envelope structure are in the following 5673 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5674 reply-to, and message-id. The date, subject, in-reply-to, and 5675 message-id fields are strings. The from, sender, reply-to, to, 5676 cc, and bcc fields are parenthesized lists of address 5677 structures. 5679 An address structure is a parenthesized list that describes an 5680 electronic mail address. The fields of an address structure 5681 are in the following order: personal name, [SMTP] at-domain- 5682 list (source route, obs-route), mailbox name, and host name. 5684 [RFC-5322] group syntax is indicated by a special form of 5685 address structure in which the host name field is NIL. If the 5686 mailbox name field is also NIL, this is an end of group marker 5687 (semi-colon in RFC 822 syntax). If the mailbox name field is 5688 non-NIL, this is a start of group marker, and the mailbox name 5689 field holds the group name phrase. 5691 If the Date, Subject, In-Reply-To, and Message-ID header fields 5692 are absent in the [RFC-5322] header, the corresponding member 5693 of the envelope is NIL; if these header fields are present but 5694 empty the corresponding member of the envelope is the empty 5695 string. 5697 Note: some servers may return a NIL envelope member in the 5698 "present but empty" case. Clients SHOULD treat NIL and 5699 empty string as identical. 5701 Note: [RFC-5322] requires that all messages have a valid 5702 Date header field. Therefore, for a well-formed message the 5703 date member in the envelope can not be NIL or the empty 5704 string. However it can be NIL for a malformed or a draft 5705 message. 5707 Note: [RFC-5322] requires that the In-Reply-To and Message- 5708 ID header fields, if present, have non-empty content. 5709 Therefore, for a well-formed message the in-reply-to and 5710 message-id members in the envelope can not be the empty 5711 string. However they can still be the empty string for a 5712 malformed message. 5714 If the From, To, Cc, and Bcc header fields are absent in the 5715 [RFC-5322] header, or are present but empty, the corresponding 5716 member of the envelope is NIL. 5718 If the Sender or Reply-To header fields are absent in the 5719 [RFC-5322] header, or are present but empty, the server sets 5720 the corresponding member of the envelope to be the same value 5721 as the from member (the client is not expected to know to do 5722 this). 5724 Note: [RFC-5322] requires that all messages have a valid 5725 From header field. Therefore, for a well-formed message the 5726 from, sender, and reply-to members in the envelope can not 5727 be NIL. However they can be NIL for a malformed or a draft 5728 message. 5730 FLAGS A parenthesized list of flags that are set for this message. 5732 INTERNALDATE A string representing the internal date of the message. 5734 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5736 UID A number expressing the unique identifier of the message. 5738 If the server chooses to send unsolicited FETCH responses, they MUST 5739 include UID FETCH item. Note that this is a new requirement when 5740 compared to RFC 3501. 5742 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5744 7.5. Server Responses - Command Continuation Request 5746 The command continuation request response is indicated by a "+" token 5747 instead of a tag. This form of response indicates that the server is 5748 ready to accept the continuation of a command from the client. The 5749 remainder of this response is a line of text. 5751 This response is used in the AUTHENTICATE command to transmit server 5752 data to the client, and request additional client data. This 5753 response is also used if an argument to any command is a 5754 synchronizing literal. 5756 The client is not permitted to send the octets of the synchronizing 5757 literal unless the server indicates that it is expected. This 5758 permits the server to process commands and reject errors on a line- 5759 by-line basis. The remainder of the command, including the CRLF that 5760 terminates a command, follows the octets of the literal. If there 5761 are any additional command arguments, the literal octets are followed 5762 by a space and those arguments. 5764 Example: C: A001 LOGIN {11} 5765 S: + Ready for additional command text 5766 C: FRED FOOBAR {7} 5767 S: + Ready for additional command text 5768 C: fat man 5769 S: A001 OK LOGIN completed 5770 C: A044 BLURDYBLOOP {102856} 5771 S: A044 BAD No such command as "BLURDYBLOOP" 5773 8. Sample IMAP4rev2 connection 5775 The following is a transcript of an IMAP4rev2 connection. A long 5776 line in this sample is broken for editorial clarity. 5778 S: * OK IMAP4rev2 Service Ready 5779 C: a001 login mrc secret 5780 S: a001 OK LOGIN completed 5781 C: a002 select inbox 5782 S: * 18 EXISTS 5783 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5784 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5785 S: * LIST () "/" INBOX ("OLDNAME" ("inbox")) 5786 S: a002 OK [READ-WRITE] SELECT completed 5787 C: a003 fetch 12 full 5788 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5789 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5790 "IMAP4rev2 WG mtg summary and minutes" 5791 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5792 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5793 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5794 ((NIL NIL "imap" "cac.washington.edu")) 5795 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5796 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5797 "") 5798 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5799 92)) 5800 S: a003 OK FETCH completed 5801 C: a004 fetch 12 body[header] 5802 S: * 12 FETCH (BODY[HEADER] {342} 5803 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5804 S: From: Terry Gray 5805 S: Subject: IMAP4rev2 WG mtg summary and minutes 5806 S: To: imap@cac.washington.edu 5807 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5808 S: Message-Id: 5809 S: MIME-Version: 1.0 5810 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5811 S: 5812 S: ) 5813 S: a004 OK FETCH completed 5814 C: a005 store 12 +flags \deleted 5815 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5816 S: a005 OK +FLAGS completed 5817 C: a006 logout 5818 S: * BYE IMAP4rev2 server terminating connection 5819 S: a006 OK LOGOUT completed 5821 9. Formal Syntax 5823 The following syntax specification uses the Augmented Backus-Naur 5824 Form (ABNF) notation as specified in [ABNF]. 5826 In the case of alternative or optional rules in which a later rule 5827 overlaps an earlier rule, the rule which is listed earlier MUST take 5828 priority. For example, "\Seen" when parsed as a flag is the \Seen 5829 flag name and not a flag-extension, even though "\Seen" can be parsed 5830 as a flag-extension. Some, but not all, instances of this rule are 5831 noted below. 5833 Note: [ABNF] rules MUST be followed strictly; in particular: 5835 (1) Except as noted otherwise, all alphabetic characters are case- 5836 insensitive. The use of upper or lower case characters to define 5837 token strings is for editorial clarity only. Implementations MUST 5838 accept these strings in a case-insensitive fashion. 5840 (2) In all cases, SP refers to exactly one space. It is NOT 5841 permitted to substitute TAB, insert additional spaces, or 5842 otherwise treat SP as being equivalent to LWSP. 5844 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5846 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5847 addr-host ")" 5849 addr-adl = nstring 5850 ; Holds route from [RFC-5322] obs-route if 5851 ; non-NIL 5853 addr-host = nstring 5854 ; NIL indicates [RFC-5322] group syntax. 5855 ; Otherwise, holds [RFC-5322] domain name 5857 addr-mailbox = nstring 5858 ; NIL indicates end of [RFC-5322] group; if 5859 ; non-NIL and addr-host is NIL, holds 5860 ; [RFC-5322] group name. 5861 ; Otherwise, holds [RFC-5322] local-part 5862 ; after removing [RFC-5322] quoting 5864 addr-name = nstring 5865 ; If non-NIL, holds phrase from [RFC-5322] 5866 ; mailbox after removing [RFC-5322] quoting 5868 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5869 literal 5871 append-uid = uniqueid 5873 astring = 1*ASTRING-CHAR / string 5874 ASTRING-CHAR = ATOM-CHAR / resp-specials 5876 atom = 1*ATOM-CHAR 5878 ATOM-CHAR = 5880 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5881 quoted-specials / resp-specials 5883 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5884 *(CRLF base64) 5886 auth-type = atom 5887 ; Defined by [SASL] 5889 base64 = *(4base64-char) [base64-terminal] 5891 base64-char = ALPHA / DIGIT / "+" / "/" 5892 ; Case-sensitive 5894 base64-terminal = (2base64-char "==") / (3base64-char "=") 5896 body = "(" (body-type-1part / body-type-mpart) ")" 5898 body-extension = nstring / number / number64 / 5899 "(" body-extension *(SP body-extension) ")" 5900 ; Future expansion. Client implementations 5901 ; MUST accept body-extension fields. Server 5902 ; implementations MUST NOT generate 5903 ; body-extension fields except as defined by 5904 ; future standard or standards-track 5905 ; revisions of this specification. 5907 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5908 [SP body-fld-loc *(SP body-extension)]]] 5909 ; MUST NOT be returned on non-extensible 5910 ; "BODY" fetch 5912 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5913 [SP body-fld-loc *(SP body-extension)]]] 5914 ; MUST NOT be returned on non-extensible 5915 ; "BODY" fetch 5917 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5918 body-fld-enc SP body-fld-octets 5920 body-fld-desc = nstring 5921 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5923 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5924 "QUOTED-PRINTABLE") DQUOTE) / string 5925 ; Content-Transfer-Encoding header field value. 5926 ; Defaults to "7BIT" (as per RFC 2045) 5927 ; if not present in the body part. 5929 body-fld-id = nstring 5931 body-fld-lang = nstring / "(" string *(SP string) ")" 5933 body-fld-loc = nstring 5935 body-fld-lines = number64 5937 body-fld-md5 = nstring 5939 body-fld-octets = number 5941 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5943 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5944 [SP body-ext-1part] 5946 body-type-basic = media-basic SP body-fields 5947 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5949 body-type-mpart = 1*body SP media-subtype 5950 [SP body-ext-mpart] 5951 ; MULTIPART body part 5953 body-type-msg = media-message SP body-fields SP envelope 5954 SP body SP body-fld-lines 5956 body-type-text = media-text SP body-fields SP body-fld-lines 5958 capability = ("AUTH=" auth-type) / atom 5959 ; New capabilities MUST begin with "X" or be 5960 ; registered with IANA in 5961 ; a standards-track, an experimental 5962 ; or an informational RFC. 5964 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5965 *(SP capability) 5966 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5967 ; and LOGINDISABLED capabilities. 5968 ; Servers which offer RFC 1730 compatibility MUST 5969 ; list "IMAP4" as the first capability. 5970 ; Servers which offer RFC 3501 compatibility MUST 5971 ; list "IMAP4rev1" as one of capabilities. 5973 CHAR = 5975 CHAR8 = %x01-ff 5976 ; any OCTET except NUL, %x00 5978 charset = atom / quoted 5980 childinfo-extended-item = "CHILDINFO" SP "(" 5981 list-select-base-opt-quoted 5982 *(SP list-select-base-opt-quoted) ")" 5983 ; Extended data item (mbox-list-extended-item) 5984 ; returned when the RECURSIVEMATCH 5985 ; selection option is specified. 5986 ; Note 1: the CHILDINFO extended data item tag can be 5987 ; returned with and without surrounding quotes, as per 5988 ; mbox-list-extended-item-tag production. 5989 ; Note 2: The selection options are always returned 5990 ; quoted, unlike their specification in 5991 ; the extended LIST command. 5993 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5994 ; attributes for CHILDREN return option, at most one 5995 ; possible per LIST response 5997 command = tag SP (command-any / command-auth / command-nonauth / 5998 command-select) CRLF 5999 ; Modal based on state 6001 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / x-command 6002 ; Valid in all states 6004 command-auth = append / create / delete / enable / examine / list / 6005 Namespace-Command / 6006 rename / select / status / subscribe / unsubscribe / 6007 idle 6008 ; Valid only in Authenticated or Selected state 6010 command-nonauth = login / authenticate / "STARTTLS" 6011 ; Valid only when in Not Authenticated state 6013 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 6014 move / fetch / store / search / uid 6015 ; Valid only when in Selected state 6017 continue-req = "+" SP (resp-text / base64) CRLF 6019 copy = "COPY" SP sequence-set SP mailbox 6021 create = "CREATE" SP mailbox 6022 ; Use of INBOX gives a NO error 6024 date = date-text / DQUOTE date-text DQUOTE 6026 date-day = 1*2DIGIT 6027 ; Day of month 6029 date-day-fixed = (SP DIGIT) / 2DIGIT 6030 ; Fixed-format version of date-day 6032 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 6033 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 6035 date-text = date-day "-" date-month "-" date-year 6037 date-year = 4DIGIT 6039 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 6040 SP time SP zone DQUOTE 6042 delete = "DELETE" SP mailbox 6043 ; Use of INBOX gives a NO error 6045 digit-nz = %x31-39 6046 ; 1-9 6048 eitem-standard-tag = atom 6049 ; a tag for LIST extended data item defined in a Standard 6050 ; Track or Experimental RFC. 6052 eitem-vendor-tag = vendor-token "-" atom 6053 ; a vendor-specific tag for LIST extended data item 6055 enable = "ENABLE" 1*(SP capability) 6057 enable-data = "ENABLED" *(SP capability) 6059 envelope = "(" env-date SP env-subject SP env-from SP 6060 env-sender SP env-reply-to SP env-to SP env-cc SP 6061 env-bcc SP env-in-reply-to SP env-message-id ")" 6063 env-bcc = "(" 1*address ")" / nil 6064 env-cc = "(" 1*address ")" / nil 6066 env-date = nstring 6068 env-from = "(" 1*address ")" / nil 6070 env-in-reply-to = nstring 6072 env-message-id = nstring 6074 env-reply-to = "(" 1*address ")" / nil 6076 env-sender = "(" 1*address ")" / nil 6078 env-subject = nstring 6080 env-to = "(" 1*address ")" / nil 6082 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 6083 *(SP search-return-data) 6084 ; ESEARCH response replaces SEARCH response 6085 ; from IMAP4rev1. 6087 examine = "EXAMINE" SP mailbox 6089 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 6090 fetch-att / "(" fetch-att *(SP fetch-att) ")") 6092 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 6093 "RFC822.SIZE" / 6094 "BODY" ["STRUCTURE"] / "UID" / 6095 "BODY" section [partial] / 6096 "BODY.PEEK" section [partial] / 6097 "BINARY" [".PEEK"] section-binary [partial] / 6098 "BINARY.SIZE" section-binary 6100 flag = "\Answered" / "\Flagged" / "\Deleted" / 6101 "\Seen" / "\Draft" / flag-keyword / flag-extension 6102 ; Does not include "\Recent" 6104 flag-extension = "\" atom 6105 ; Future expansion. Client implementations 6106 ; MUST accept flag-extension flags. Server 6107 ; implementations MUST NOT generate 6108 ; flag-extension flags except as defined by 6109 ; future standard or standards-track 6110 ; revisions of this specification. 6111 ; "\Recent" was defined in RFC 3501 6112 ; and is now deprecated. 6114 flag-fetch = flag 6116 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 6117 "$NotJunk" / "$Phishing" / atom 6119 flag-list = "(" [flag *(SP flag)] ")" 6121 flag-perm = flag / "\*" 6123 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 6125 header-fld-name = astring 6127 header-list = "(" header-fld-name *(SP header-fld-name) ")" 6129 idle = "IDLE" CRLF "DONE" 6131 initial-resp = (base64 / "=") 6132 ; "initial response" defined in 6133 ; Section 5.1 of [RFC4422] 6135 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 6136 [SP list-return-opts] 6138 list-mailbox = 1*list-char / string 6140 list-char = ATOM-CHAR / list-wildcards / resp-specials 6142 list-return-opts = "RETURN" SP 6143 "(" [return-option *(SP return-option)] ")" 6144 ; list return options, e.g., CHILDREN 6146 list-select-base-opt = "SUBSCRIBED" / option-extension 6147 ; options that can be used by themselves 6149 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 6151 list-select-independent-opt = "REMOTE" / option-extension 6152 ; options that do not syntactically interact with 6153 ; other options 6155 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 6156 ; options that require a list-select-base-opt 6157 ; to also be present 6159 list-select-opt = list-select-base-opt / list-select-independent-opt 6160 / list-select-mod-opt 6161 ; An option registration template is described in 6162 ; Section 9.3 of this document. 6164 list-select-opts = "(" [ 6165 (*(list-select-opt SP) list-select-base-opt 6166 *(SP list-select-opt)) 6167 / (list-select-independent-opt 6168 *(SP list-select-independent-opt)) 6169 ] ")" 6170 ; Any number of options may be in any order. 6171 ; If a list-select-mod-opt appears, then a 6172 ; list-select-base-opt must also appear. 6173 ; This allows these: 6174 ; () 6175 ; (REMOTE) 6176 ; (SUBSCRIBED) 6177 ; (SUBSCRIBED REMOTE) 6178 ; (SUBSCRIBED RECURSIVEMATCH) 6179 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6180 ; But does NOT allow these: 6181 ; (RECURSIVEMATCH) 6182 ; (REMOTE RECURSIVEMATCH) 6184 list-wildcards = "%" / "*" 6186 literal = "{" number64 ["+"] "}" CRLF *CHAR8 6187 ; represents the number of CHAR8s. 6188 ; A non-synchronizing literal is distinguished from 6189 ; a synchronizing literal by presence of the "+" 6190 ; before the closing "}". 6191 ; Non synchronizing literals are not allowed when 6192 ; sent from server to the client. 6194 literal8 = "~{" number64 "}" CRLF *OCTET 6195 ; represents the number of OCTETs 6196 ; in the response string. 6198 login = "LOGIN" SP userid SP password 6200 mailbox = "INBOX" / astring 6201 ; INBOX is case-insensitive. All case variants of 6202 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6203 ; not as an astring. An astring which consists of 6204 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6205 ; is considered to be INBOX and not an astring. 6206 ; Refer to section 5.1 for further 6207 ; semantic details of mailbox names. 6209 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6210 esearch-response / 6211 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6212 number SP "EXISTS" / Namespace-Response 6214 mailbox-list = "(" [mbx-list-flags] ")" SP 6215 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6216 [SP mbox-list-extended] 6217 ; This is the list information pointed to by the ABNF 6218 ; item "mailbox-data", which is defined in [IMAP4] 6220 mbox-list-extended = "(" [mbox-list-extended-item 6221 *(SP mbox-list-extended-item)] ")" 6223 mbox-list-extended-item = mbox-list-extended-item-tag SP 6224 tagged-ext-val 6226 mbox-list-extended-item-tag = astring 6227 ; The content MUST conform to either "eitem-vendor-tag" 6228 ; or "eitem-standard-tag" ABNF productions. 6230 mbox-or-pat = list-mailbox / patterns 6232 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6233 *(SP mbx-list-oflag) / 6234 mbx-list-oflag *(SP mbx-list-oflag) 6236 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6237 "\Subscribed" / "\Remote" / flag-extension 6238 ; Other flags; multiple possible per LIST response 6240 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6241 ; Selectability flags; only one per LIST response 6243 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6244 "FONT" / "MESSAGE" / "MODEL" / "VIDEO" ) DQUOTE) 6245 / string) 6246 SP media-subtype 6247 ; Defined in [MIME-IMT]. 6248 ; FONT defined in RFC 8081. 6250 media-message = DQUOTE "MESSAGE" DQUOTE SP 6251 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6252 ; Defined in [MIME-IMT] 6254 media-subtype = string 6255 ; Defined in [MIME-IMT] 6257 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6258 ; Defined in [MIME-IMT] 6260 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6262 move = "MOVE" SP sequence-set SP mailbox 6264 msg-att = "(" (msg-att-dynamic / msg-att-static) 6265 *(SP (msg-att-dynamic / msg-att-static)) ")" 6267 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6268 ; MAY change for a message 6270 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6271 "RFC822.SIZE" SP number64 / 6272 "BODY" ["STRUCTURE"] SP body / 6273 "BODY" section ["<" number ">"] SP nstring / 6274 "BINARY" section-binary SP (nstring / literal8) / 6275 "BINARY.SIZE" section-binary SP number / 6276 "UID" SP uniqueid 6277 ; MUST NOT change for a message 6279 name-component = 1*UTF8-CHAR 6280 ; MUST NOT contain ".", "/", "%", or "*" 6282 Namespace = nil / "(" 1*Namespace-Descr ")" 6284 Namespace-Command = "NAMESPACE" 6286 Namespace-Descr = "(" string SP 6287 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6288 [Namespace-Response-Extensions] ")" 6290 Namespace-Response-Extensions = *Namespace-Response-Extension 6292 Namespace-Response-Extension = SP string SP 6293 "(" string *(SP string) ")" 6295 Namespace-Response = "NAMESPACE" SP Namespace 6296 SP Namespace SP Namespace 6297 ; The first Namespace is the Personal Namespace(s). 6298 ; The second Namespace is the Other Users' 6299 ; Namespace(s). 6300 ; The third Namespace is the Shared Namespace(s). 6302 nil = "NIL" 6303 nstring = string / nil 6305 number = 1*DIGIT 6306 ; Unsigned 32-bit integer 6307 ; (0 <= n < 4,294,967,296) 6309 number64 = 1*DIGIT 6310 ; Unsigned 63-bit integer 6311 ; (0 <= n <= 9,223,372,036,854,775,807) 6313 nz-number = digit-nz *DIGIT 6314 ; Non-zero unsigned 32-bit integer 6315 ; (0 < n < 4,294,967,296) 6317 nz-number64 = digit-nz *DIGIT 6318 ; Unsigned 63-bit integer 6319 ; (0 < n <= 9,223,372,036,854,775,807) 6321 oldname-extended-item = "OLDNAME" SP "(" mailbox ")" 6322 ; Extended data item (mbox-list-extended-item) 6323 ; returned in a LIST response when a mailbox is 6324 ; renamed or deleted. Also returned when 6325 ; the server canonicalized the provided mailbox 6326 ; name. 6327 ; Note 1: the OLDNAME tag can be returned 6328 ; with or without surrounding quotes, as per 6329 ; mbox-list-extended-item-tag production. 6331 option-extension = (option-standard-tag / option-vendor-tag) 6332 [SP option-value] 6334 option-standard-tag = atom 6335 ; an option defined in a Standards Track or 6336 ; Experimental RFC 6338 option-val-comp = astring / 6339 option-val-comp *(SP option-val-comp) / 6340 "(" option-val-comp ")" 6342 option-value = "(" option-val-comp ")" 6344 option-vendor-tag = vendor-token "-" atom 6345 ; a vendor-specific option, non-standard 6347 partial-range = number64 ["." nz-number64] 6348 ; Copied from RFC 5092 (IMAP URL) 6349 ; and updated to support 64bit sizes. 6351 partial = "<" number64 "." nz-number64 ">" 6352 ; Partial FETCH request. 0-based offset of 6353 ; the first octet, followed by the number of octets 6354 ; in the fragment. 6356 password = astring 6358 patterns = "(" list-mailbox ")" 6359 ; [RFC5258] supports multiple patterns, 6360 ; but this document only requires one 6361 ; to be supported. 6362 ; If the server is also implementing 6363 ; [RFC5258], "patterns" syntax from that 6364 ; document must be followed. 6366 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6368 QUOTED-CHAR = / 6369 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6371 quoted-specials = DQUOTE / "\" 6373 rename = "RENAME" SP mailbox SP mailbox 6374 ; Use of INBOX as a destination gives a NO error 6376 response = *(continue-req / response-data) response-done 6378 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6379 mailbox-data / message-data / capability-data / 6380 enable-data) CRLF 6382 response-done = response-tagged / response-fatal 6384 response-fatal = "*" SP resp-cond-bye CRLF 6385 ; Server closes connection immediately 6387 response-tagged = tag SP resp-cond-state CRLF 6389 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6391 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6393 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6394 ; Authentication condition 6396 resp-cond-bye = "BYE" SP resp-text 6398 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6399 ; Status condition 6401 resp-specials = "]" 6403 resp-text = ["[" resp-text-code "]" SP] [text] 6405 resp-text-code = "ALERT" / 6406 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6407 capability-data / "PARSE" / 6408 "PERMANENTFLAGS" SP 6409 "(" [flag-perm *(SP flag-perm)] ")" / 6410 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6411 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6412 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6413 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6414 "AUTHORIZATIONFAILED" / "EXPIRED" / 6415 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6416 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6417 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6418 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6419 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6420 "CLOSED" / 6421 "UNKNOWN-CTE" / 6422 atom [SP 1*] 6424 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6425 option-extension 6427 search = "SEARCH" [search-return-opts] 6428 SP search-program 6430 search-correlator = SP "(" "TAG" SP tag-string ")" 6432 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6433 "BEFORE" SP date / "BODY" SP astring / 6434 "CC" SP astring / "DELETED" / "FLAGGED" / 6435 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6436 "ON" SP date / "SEEN" / 6437 "SINCE" SP date / "SUBJECT" SP astring / 6438 "TEXT" SP astring / "TO" SP astring / 6439 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6440 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6441 ; Above this line were in [IMAP2] 6442 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6443 "LARGER" SP number64 / "NOT" SP search-key / 6444 "OR" SP search-key SP search-key / 6445 "SENTBEFORE" SP date / "SENTON" SP date / 6446 "SENTSINCE" SP date / "SMALLER" SP number64 / 6447 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6448 "(" search-key *(SP search-key) ")" 6450 search-modifier-name = tagged-ext-label 6452 search-mod-params = tagged-ext-val 6453 ; This non-terminal shows recommended syntax 6454 ; for future extensions. 6456 search-program = ["CHARSET" SP charset SP] 6457 search-key *(SP search-key) 6458 ; CHARSET argument to SEARCH MUST be 6459 ; registered with IANA. 6461 search-ret-data-ext = search-modifier-name SP search-return-value 6462 ; Note that not every SEARCH return option 6463 ; is required to have the corresponding 6464 ; ESEARCH return data. 6466 search-return-data = "MIN" SP nz-number / 6467 "MAX" SP nz-number / 6468 "ALL" SP sequence-set / 6469 "COUNT" SP number / 6470 search-ret-data-ext 6471 ; All return data items conform to 6472 ; search-ret-data-ext syntax. 6473 ; Note that "$" marker is not allowed 6474 ; after the ALL return data item. 6476 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6477 *(SP search-return-opt)] ")" 6479 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6480 "SAVE" / 6481 search-ret-opt-ext 6482 ; conforms to generic search-ret-opt-ext 6483 ; syntax 6485 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6487 search-return-value = tagged-ext-val 6488 ; Data for the returned search option. 6489 ; A single "nz-number"/"number"/"number64" value 6490 ; can be returned as an atom (i.e., without 6491 ; quoting). A sequence-set can be returned 6492 ; as an atom as well. 6494 section = "[" [section-spec] "]" 6495 section-binary = "[" [section-part] "]" 6497 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6498 "TEXT" 6499 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6501 section-part = nz-number *("." nz-number) 6502 ; body part reference. 6503 ; Allows for accessing nested body parts. 6505 section-spec = section-msgtext / (section-part ["." section-text]) 6507 section-text = section-msgtext / "MIME" 6508 ; text other than actual body part (headers, etc.) 6510 select = "SELECT" SP mailbox 6512 seq-number = nz-number / "*" 6513 ; message sequence number (COPY, FETCH, STORE 6514 ; commands) or unique identifier (UID COPY, 6515 ; UID FETCH, UID STORE commands). 6516 ; * represents the largest number in use. In 6517 ; the case of message sequence numbers, it is 6518 ; the number of messages in a non-empty mailbox. 6519 ; In the case of unique identifiers, it is the 6520 ; unique identifier of the last message in the 6521 ; mailbox or, if the mailbox is empty, the 6522 ; mailbox's current UIDNEXT value. 6523 ; The server should respond with a tagged BAD 6524 ; response to a command that uses a message 6525 ; sequence number greater than the number of 6526 ; messages in the selected mailbox. This 6527 ; includes "*" if the selected mailbox is empty. 6529 seq-range = seq-number ":" seq-number 6530 ; two seq-number values and all values between 6531 ; these two regardless of order. 6532 ; Example: 2:4 and 4:2 are equivalent and indicate 6533 ; values 2, 3, and 4. 6534 ; Example: a unique identifier sequence range of 6535 ; 3291:* includes the UID of the last message in 6536 ; the mailbox, even if that value is less than 3291. 6538 sequence-set = (seq-number / seq-range) ["," sequence-set] 6539 ; set of seq-number values, regardless of order. 6540 ; Servers MAY coalesce overlaps and/or execute the 6541 ; sequence in any order. 6542 ; Example: a message sequence number set of 6543 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6544 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6545 ; Example: a message sequence number set of *:4,5:7 6546 ; for a mailbox with 10 messages is equivalent to 6547 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6548 ; overlap coalesced to be 4,5,6,7,8,9,10. 6550 sequence-set =/ seq-last-command 6551 ; Allow for "result of the last command" indicator. 6553 seq-last-command = "$" 6555 status = "STATUS" SP mailbox SP 6556 "(" status-att *(SP status-att) ")" 6558 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6559 "UNSEEN" / "DELETED" / "SIZE" 6561 status-att-val = ("MESSAGES" SP number) / 6562 ("UIDNEXT" SP nz-number) / 6563 ("UIDVALIDITY" SP nz-number) / 6564 ("UNSEEN" SP number) / 6565 ("DELETED" SP number) / 6566 ("SIZE" SP number64) 6567 ; Extensions to the STATUS responses 6568 ; should extend this production. 6569 ; Extensions should use the generic 6570 ; syntax defined by tagged-ext. 6572 status-att-list = status-att-val *(SP status-att-val) 6574 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6575 ; This ABNF production complies with 6576 ; syntax. 6578 store = "STORE" SP sequence-set SP store-att-flags 6580 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6581 (flag-list / (flag *(SP flag))) 6583 string = quoted / literal 6585 subscribe = "SUBSCRIBE" SP mailbox 6587 tag = 1* 6589 tag-string = astring 6590 ; represented as 6592 tagged-ext-label = tagged-label-fchar *tagged-label-char 6593 ; Is a valid RFC 3501 "atom". 6595 tagged-label-fchar = ALPHA / "-" / "_" / "." 6597 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6599 tagged-ext-comp = astring / 6600 tagged-ext-comp *(SP tagged-ext-comp) / 6601 "(" tagged-ext-comp ")" 6602 ; Extensions that follow this general 6603 ; syntax should use nstring instead of 6604 ; astring when appropriate in the context 6605 ; of the extension. 6606 ; Note that a message set or a "number" 6607 ; can always be represented as an "atom". 6608 ; An URL should be represented as 6609 ; a "quoted" string. 6611 tagged-ext-simple = sequence-set / number / number64 6613 tagged-ext-val = tagged-ext-simple / 6614 "(" [tagged-ext-comp] ")" 6616 text = 1*(TEXT-CHAR / UTF8-2 / UTF8-3 / UTF8-4) 6617 ; Non ASCII text can only be returned 6618 ; after ENABLE IMAP4rev2 command 6620 TEXT-CHAR = 6622 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6623 ; Hours minutes seconds 6625 uid = "UID" SP 6626 (copy / move / fetch / search / store / uid-expunge) 6627 ; Unique identifiers used instead of message 6628 ; sequence numbers 6630 uid-expunge = "EXPUNGE" SP sequence-set 6631 ; Unique identifiers used instead of message 6632 ; sequence numbers 6634 uid-set = (uniqueid / uid-range) *("," uid-set) 6636 uid-range = (uniqueid ":" uniqueid) 6637 ; two uniqueid values and all values 6638 ; between these two regards of order. 6639 ; Example: 2:4 and 4:2 are equivalent. 6641 uniqueid = nz-number 6642 ; Strictly ascending 6644 unsubscribe = "UNSUBSCRIBE" SP mailbox 6646 userid = astring 6648 UTF8-2 = 6650 UTF8-3 = 6652 UTF8-4 = 6654 vendor-token = "vendor." name-component 6655 ; Definition copied from RFC 2244. 6656 ; MUST be registered with IANA 6658 x-command = "X" atom 6660 zone = ("+" / "-") 4DIGIT 6661 ; Signed four-digit value of hhmm representing 6662 ; hours and minutes east of Greenwich (that is, 6663 ; the amount that the given time differs from 6664 ; Universal Time). Subtracting the timezone 6665 ; from the given time will give the UT form. 6666 ; The Universal Time zone is "+0000". 6668 10. Author's Note 6670 This document is a revision or rewrite of earlier documents, and 6671 supercedes the protocol specification in those documents: RFC 3501, 6672 RFC 2060, RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and 6673 RFC 1064. 6675 11. Security Considerations 6677 IMAP4rev2 protocol transactions, including electronic mail data, are 6678 sent in the clear over the network unless protection from snooping is 6679 negotiated. This can be accomplished either by the use of IMAPS 6680 service, STARTTLS command, negotiated privacy protection in the 6681 AUTHENTICATE command, or some other protection mechanism. 6683 11.1. STARTTLS Security Considerations 6685 IMAP client and server implementations MUST comply with relevant TLS 6686 recommendations from [RFC8314]. 6688 Clients and servers MUST implement TLS 1.2 [TLS-1.2] or newer. Use 6689 of TLS 1.3 [TLS-1.3] is RECOMMENDED. TLS 1.2 may be used only in 6690 cases where the other party has not yet implemented TLS 1.3. 6691 Additionally, when using TLS 1.2, IMAP implementations MUST implement 6692 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6693 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS-1.2] cipher suite. 6694 This is important as it assures that any two compliant 6695 implementations can be configured to interoperate. Other TLS cipher 6696 suites recommended in RFC 7525 are RECOMMENDED: 6697 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6698 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6699 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6700 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6702 The list of mandatory-to-implement TLS 1.3 cipher suites is described 6703 in Section 9.1 of [TLS-1.3]. 6705 During the TLS negotiation [TLS-1.3][TLS-1.2], the client MUST check 6706 its understanding of the server hostname against the server's 6707 identity as presented in the server Certificate message, in order to 6708 prevent man-in-the-middle attacks. This procedure is described in 6709 [RFC7817]. 6711 Both the client and server MUST check the result of the STARTTLS 6712 command and subsequent TLS ([TLS-1.3][TLS-1.2]) negotiation to see 6713 whether acceptable authentication and/or privacy was achieved. 6715 11.2. COPYUID and APPENDUID response codes 6717 The COPYUID and APPENDUID response codes return information about the 6718 mailbox, which may be considered sensitive if the mailbox has 6719 permissions set that permit the client to COPY or APPEND to the 6720 mailbox, but not SELECT or EXAMINE it. 6722 Consequently, these response codes SHOULD NOT be issued if the client 6723 does not have access to SELECT or EXAMINE the mailbox. 6725 11.3. LIST command and Other Users' namespace 6727 In response to a LIST command containing an argument of the Other 6728 Users' Namespace prefix, a server SHOULD NOT list users that have not 6729 granted list access to their personal mailboxes to the currently 6730 authenticated user. Providing such a list, could compromise security 6731 by potentially disclosing confidential information of who is located 6732 on the server, or providing a starting point of a list of user 6733 accounts to attack. 6735 11.4. Other Security Considerations 6737 A server error message for an AUTHENTICATE command which fails due to 6738 invalid credentials SHOULD NOT detail why the credentials are 6739 invalid. 6741 Use of the LOGIN command sends passwords in the clear. This can be 6742 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6743 that does not use plaintext passwords, by first negotiating 6744 encryption via STARTTLS or some other protection mechanism. 6746 A server implementation MUST implement a configuration that, at the 6747 time of authentication, requires: 6748 (1) The STARTTLS command has been negotiated. 6749 OR 6750 (2) Some other mechanism that protects the session from password 6751 snooping has been provided. 6752 OR 6753 (3) The following measures are in place: 6754 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6755 (such as PLAIN) using plaintext passwords are NOT advertised in the 6756 CAPABILITY list. 6757 AND 6758 (b) The LOGIN command returns an error even if the password is 6759 correct. 6760 AND 6761 (c) The AUTHENTICATE command returns an error with all [SASL] 6762 mechanisms that use plaintext passwords, even if the password is 6763 correct. 6765 A server error message for a failing LOGIN command SHOULD NOT specify 6766 that the user name, as opposed to the password, is invalid. 6768 A server SHOULD have mechanisms in place to limit or delay failed 6769 AUTHENTICATE/LOGIN attempts. 6771 Additional security considerations are discussed in the section 6772 discussing the AUTHENTICATE (see Section 6.2.2) and LOGIN (see 6773 Section 6.2.3) commands. 6775 12. IANA Considerations 6777 IANA is requested to update "Service Names and Transport Protocol 6778 Port Numbers" registry as follows: 6780 1. Registration for TCP port 143 and the corresponding "imap" 6781 service name should be updated to point to this document and RFC 6782 3501. 6784 2. Registration for TCP port 993 and the corresponding "imaps" 6785 service name should be updated to point to this document, RFC 6786 8314 and RFC 3501. 6788 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6789 in the registry. 6791 Additional IANA actions are specified in subsection of this section. 6793 12.1. Updates to IMAP4 Capabilities registry 6795 IMAP4 capabilities are registered by publishing a standards track or 6796 IESG approved informational or experimental RFC. The registry is 6797 currently located at: https://www.iana.org/assignments/ 6798 imap4-capabilities 6800 As this specification revises the AUTH= prefix, STARTTLS and 6801 LOGINDISABLED extensions, IANA is requested to update registry 6802 entries for these 3 extensions to point to this document. 6804 12.2. GSSAPI/SASL service name 6806 GSSAPI/Kerberos/SASL service names are registered by publishing a 6807 standards track or IESG approved experimental RFC. The registry is 6808 currently located at: https://www.iana.org/assignments/gssapi- 6809 service-names 6811 IANA is requested to update the "imap" service name previously 6812 registered in RFC 3501, to point to this document. 6814 12.3. LIST Selection Options, LIST Return Options, LIST extended data 6815 items 6817 [RFC5258] specifies IANA registration procedures for LIST Selection 6818 Options, LIST Return Options, LIST extended data items. This 6819 document doesn't change these registration procedures. In particular 6820 LIST selection options Section 6.3.9.1 and LIST return options 6821 Section 6.3.9.2 are registered using the procedure specified in 6822 Section 9 of [RFC5258] (and using the registration template from 6823 Section 9.3 of [RFC5258]). LIST Extended Data Items are registered 6824 using the registration template from Section 9.6 of [RFC5258]). 6826 IANA is requested to add a reference to [RFCXXXX] for the "OLDNAME" 6827 LIST-EXTENDED extended data item entry. This is in addition to the 6828 existing reference to [RFC5465]. 6830 13. References 6832 13.1. Normative References 6834 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6835 Protocol version 4 - LIST Command Extensions", RFC 5258, 6836 DOI 10.17487/RFC5258, June 2008, 6837 . 6839 [RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", 6840 RFC 5788, DOI 10.17487/RFC5788, March 2010, 6841 . 6843 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6844 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6845 . 6847 [ANONYMOUS] 6848 Zeilenga, K., "Anonymous Simple Authentication and 6849 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6850 . 6852 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6853 Procedures", BCP 19, RFC 2978, October 2000, 6854 . 6856 [SCRAM-SHA-256] 6857 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6858 Authentication and Security Layer (SASL) Mechanisms", 6859 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6860 . 6862 [DISPOSITION] 6863 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6864 Presentation Information in Internet Messages: The 6865 Content-Disposition Header Field", RFC 2183, August 1997, 6866 . 6868 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6869 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6870 . 6872 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6873 Requirement Levels", BCP 14, RFC 2119, 6874 DOI 10.17487/RFC2119, March 1997, 6875 . 6877 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6878 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6879 May 2017, . 6881 [LANGUAGE-TAGS] 6882 Alvestrand, H., "Content Language Headers", RFC 3282, May 6883 2002, . 6885 [LOCATION] 6886 Palme, J., Hopmann, A., and N. Shelness, "MIME 6887 Encapsulation of Aggregate Documents, such as HTML 6888 (MHTML)", RFC 2557, March 1999, 6889 . 6891 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6892 RFC 1864, October 1995, 6893 . 6895 [MIME-HDRS] 6896 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6897 Part Three: Message Header Extensions for Non-ASCII Text", 6898 RFC 2047, November 1996, 6899 . 6901 [MIME-IMB] 6902 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6903 Extensions (MIME) Part One: Format of Internet Message 6904 Bodies", RFC 2045, November 1996, 6905 . 6907 [MIME-IMT] 6908 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6909 Extensions (MIME) Part Two: Media Types", RFC 2046, 6910 November 1996, . 6912 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6913 Word Extensions: Character Sets, Languages, and 6914 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6915 1997, . 6917 [RFC-5322] 6918 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6919 October 2008, . 6921 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6922 Authentication and Security Layer (SASL)", RFC 4422, June 6923 2006, . 6925 [TLS-1.2] Dierks, T. and E. Rescorla, "The Transport Layer Security 6926 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6927 . 6929 [TLS-1.3] Rescorla, E., "The Transport Layer Security (TLS) Protocol 6930 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 6931 . 6933 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6934 Transformation Format of Unicode", RFC 2152, May 1997, 6935 . 6937 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6938 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6939 2003, . 6941 [MULTIAPPEND] 6942 Crispin, M., "Internet Message Access Protocol (IMAP) - 6943 MULTIAPPEND Extension", RFC 3502, March 2003, 6944 . 6946 [NET-UNICODE] 6947 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6948 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6949 . 6951 [I18N-HDRS] 6952 Yang, A., Steele, S., and N. Freed, "Internationalized 6953 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6954 2012, . 6956 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6957 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6958 . 6960 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6961 Server Identity Check Procedure for Email-Related 6962 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6963 . 6965 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6966 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6967 February 2017, . 6969 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6970 Use of Transport Layer Security (TLS) for Email Submission 6971 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6972 . 6974 [IMAP-IMPLEMENTATION] 6975 Leiba, B., "IMAP4 Implementation Recommendations", 6976 RFC 2683, September 1999, 6977 . 6979 [IMAP-MULTIACCESS] 6980 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6981 RFC 2180, July 1997, 6982 . 6984 13.2. Informative References (related protocols) 6986 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 6987 profile for Internet Message Access Protocol (IMAP)", 6988 RFC 3503, DOI 10.17487/RFC3503, March 2003, 6989 . 6991 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6992 Protocol - SORT and THREAD Extensions", RFC 5256, 6993 DOI 10.17487/RFC5256, June 2008, 6994 . 6996 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6997 DOI 10.17487/RFC2193, September 1997, 6998 . 7000 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 7001 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 7002 DOI 10.17487/RFC3348, July 2002, 7003 . 7005 [RFC5465] Gulbrandsen, A., King, C., and A. Melnikov, "The IMAP 7006 NOTIFY Extension", RFC 5465, DOI 10.17487/RFC5465, 7007 February 2009, . 7009 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 7010 RFC 7888, DOI 10.17487/RFC7888, May 2016, 7011 . 7013 [IMAP-DISC] 7014 Melnikov, A., Ed., "Synchronization Operations for 7015 Disconnected IMAP4 Clients", RFC 4549, June 2006, 7016 . 7018 [IMAP-I18N] 7019 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 7020 Message Access Protocol Internationalization", RFC 5255, 7021 DOI 10.17487/RFC5255, June 2008, 7022 . 7024 [IMAP-MODEL] 7025 Crispin, M., "Distributed Electronic Mail Models in 7026 IMAP4", RFC 1733, December 1994, 7027 . 7029 [IMAP-UTF-8] 7030 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 7031 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 7032 2013, . 7034 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 7035 October 2008, . 7037 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 7038 DOI 10.17487/RFC3516, April 2003, 7039 . 7041 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 7042 RFC 4314, December 2005, 7043 . 7045 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 7046 1997, . 7048 [IMAP-URL] 7049 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 7050 RFC 5092, DOI 10.17487/RFC5092, November 2007, 7051 . 7053 [IMAP-KEYWORDS-REG] 7054 IANA, "IMAP and JMAP Keywords", December 2009, 7055 . 7058 [IMAP-MAILBOX-NAME-ATTRS-REG] 7059 IANA, "IMAP Mailbox Name Attributes", June 2018, 7060 . 7063 [CHARSET-REG] 7064 IANA, "Character Set Registrations", May 2015, 7065 . 7068 13.3. Informative References (historical aspects of IMAP and related 7069 protocols) 7071 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 7072 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 7073 . 7075 [IMAP-COMPAT] 7076 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 7077 RFC 2061, December 1996, 7078 . 7080 [IMAP-HISTORICAL] 7081 Crispin, M., "IMAP4 Compatibility with IMAP2 and 7082 IMAP2bis", RFC 1732, December 1994, 7083 . 7085 [IMAP-OBSOLETE] 7086 Crispin, M., "Internet Message Access Protocol - Obsolete 7087 Syntax", RFC 2062, December 1996, 7088 . 7090 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 7091 2", RFC 1176, August 1990, 7092 . 7094 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 7095 TEXT MESSAGES", STD 11, RFC 822, August 1982, 7096 . 7098 [IMAP-TLS] 7099 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 7100 RFC 2595, June 1999, 7101 . 7103 Appendix A. Backward compatibility with IMAP4rev1 7105 An implementation that wants to remain compatible with IMAP4rev1 can 7106 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 7107 response code. While some IMAP4rev1 responses were removed in 7108 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 7110 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 7111 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 7113 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 7114 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 7115 Consider implementation of mechanisms described or referenced in 7116 [IMAP-UTF-8] to achieve this goal. 7118 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 7119 intending to be compatible with IMAP4rev1 servers MUST be compatible 7120 with the international mailbox naming convention described in the 7121 following subsection. 7123 Also see Appendix D for special considerations for servers that 7124 support 63 bit body part/message sizes and want to advertise support 7125 for both IMAP4rev1 and IMAP4rev2. 7127 A.1. Mailbox International Naming Convention for compatibility with 7128 IMAP4rev1 7130 Support for the Mailbox International Naming Convention described in 7131 this section is not required for IMAP4rev2-only clients and servers. 7132 It is only used for backward compatibility with IMAP4rev1 7133 implementations. 7135 By convention, international mailbox names in IMAP4rev1 are specified 7136 using a modified version of the UTF-7 encoding described in [UTF-7]. 7137 Modified UTF-7 may also be usable in servers that implement an 7138 earlier version of this protocol. 7140 In modified UTF-7, printable US-ASCII characters, except for "&", 7141 represent themselves; that is, characters with octet values 0x20-0x25 7142 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 7143 octet sequence "&-". 7145 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 7146 represented in modified BASE64, with a further modification from 7147 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 7148 used to represent any printing US-ASCII character which can represent 7149 itself. Only characters inside the modified BASE64 alphabet are 7150 permitted in modified BASE64 text. 7152 "&" is used to shift to modified BASE64 and "-" to shift back to US- 7153 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 7154 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 7155 "&") are not permitted. However, all names start in US-ASCII, and 7156 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 7157 ISO-10646 character MUST end with a "-"). 7159 The purpose of these modifications is to correct the following 7160 problems with UTF-7: 7162 1. UTF-7 uses the "+" character for shifting; this conflicts with 7163 the common use of "+" in mailbox names, in particular USENET 7164 newsgroup names. 7166 2. UTF-7's encoding is BASE64 which uses the "/" character; this 7167 conflicts with the use of "/" as a popular hierarchy delimiter. 7169 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 7170 the use of "\" as a popular hierarchy delimiter. 7172 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 7173 the use of "~" in some servers as a home directory indicator. 7175 5. UTF-7 permits multiple alternate forms to represent the same 7176 string; in particular, printable US-ASCII characters can be 7177 represented in encoded form. 7179 Although modified UTF-7 is a convention, it establishes certain 7180 requirements on server handling of any mailbox name with an embedded 7181 "&" character. In particular, server implementations MUST preserve 7182 the exact form of the modified BASE64 portion of a modified UTF-7 7183 name and treat that text as case-sensitive, even if names are 7184 otherwise case-insensitive or case-folded. 7186 Server implementations SHOULD verify that any mailbox name with an 7187 embedded "&" character, used as an argument to CREATE, is: in the 7188 correctly modified UTF-7 syntax, has no superfluous shifts, and has 7189 no encoding in modified BASE64 of any printing US-ASCII character 7190 which can represent itself. However, client implementations MUST NOT 7191 depend upon the server doing this, and SHOULD NOT attempt to create a 7192 mailbox name with an embedded "&" character unless it complies with 7193 the modified UTF-7 syntax. 7195 Server implementations which export a mail store that does not follow 7196 the modified UTF-7 convention MUST convert to modified UTF-7 any 7197 mailbox name that contains either non-ASCII characters or the "&" 7198 character. 7200 For example, here is a mailbox name which mixes English, Chinese, 7201 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 7203 For example, the string "&Jjo!" is not a valid mailbox name 7204 because it does not contain a shift to US-ASCII before the "!". 7205 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 7206 not permitted because it contains a superfluous shift. The 7207 correct form is "&U,BTF2XlZyyKng-". 7209 Appendix B. Backward compatibility with BINARY extension 7211 IMAP4rev2 incorporates subset of functionality provided by the BINARY 7212 extension [RFC3516], in particular it includes additional FETCH items 7213 (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions to the 7214 APPEND command. IMAP4rev2 implementations that supports full RFC 7215 3516 functionality need to also advertise the BINARY capability in 7216 the CAPABILITY response/response code. 7218 Appendix C. Backward compatibility with LIST-EXTENDED extension 7220 IMAP4rev2 incorporates most of functionality provided by the LIST- 7221 EXTENDED extension [RFC5258]. In particular, multiple mailbox 7222 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 7223 capability is also advertised in the CAPABILITY response/response 7224 code. 7226 Appendix D. 63 bit body part and message sizes 7228 IMAP4rev2 increases allowed body part and message sizes that servers 7229 can support from 32 to 63 bits. Server implementations don't have to 7230 support 63 bit long body parts/message sizes, however client 7231 implementations have to expect them. 7233 As IMAP4rev1 didn't support 63 bit long body part/message sizes, 7234 there is an interoperability issue exposed by 63 bit capable servers 7235 that are accessible by both IMAP4rev1 and IMAP4rev2 email clients. 7236 As IMAP4rev1 would be unable to retrieve full content of messages 7237 bigger than 4Gb, such servers either need to replace messages bigger 7238 that 4Gb with messages under 4Gb or hide them from IMAP4rev1 clients. 7239 This document doesn't prescribe any implementation strategy to 7240 address this issue. 7242 Appendix E. Changes from RFC 3501 / IMAP4rev1 7244 Below is the summary of changes since RFC 3501: 7246 1. Support for 64bit message and body part sizes. 7248 2. Folded in IMAP NAMESPACE (RFC 2342), UNSELECT (RFC 3691), 7249 UIDPLUS (RFC 4315), ESEARCH (RFC 4731), SEARCHRES (RFC 5182), 7250 ENABLE (RFC 5161), IDLE (RFC 2177), SASL-IR (RFC 4959), LIST- 7251 EXTENDED (RFC 5258), LIST-STATUS (RFC 5819), MOVE (RFC 6851) and 7252 LITERAL- (RFC 7888) extensions. Also folded RFC 4466 (IMAP ABNF 7253 extensions), RFC 5530 (response codes), the FETCH side of the 7254 BINARY extension (RFC 3516) and the list of new mailbox 7255 attributes from SPECIAL-USE (RFC 6154). 7257 3. Added STATUS SIZE (RFC 8438) and STATUS DELETED. 7259 4. SEARCH command now requires to return ESEARCH response (SEARCH 7260 response is now deprecated). 7262 5. Clarified which SEARCH keys has to use substring match and which 7263 don't. 7265 6. Clarified that server should decode parameter value 7266 continuations as described in [RFC2231]. This requirement was 7267 hidden in RFC 2231 itself. 7269 7. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7270 mailbox is already selected now require for the CLOSED response 7271 code to be returned. 7273 8. SELECT/EXAMINE are now required to return untagged LIST 7274 response. 7276 9. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7278 10. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7279 SEARCH NEW items are now deprecated. 7281 11. Clarified that the server doesn't need to send a new 7282 PERMANENTFLAGS response code when a new keyword was successfully 7283 added and the server advertised \* earlier for the same mailbox. 7285 12. For future extensibility extended ABNF for tagged-ext-simple to 7286 allow for bare number64. 7288 13. Added SHOULD level requirement on IMAP servers to support 7289 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7291 14. Mailbox names and message headers now allow for UTF-8. Support 7292 for Modified UTF-7 in mailbox names is not required, unless 7293 compatibility with IMAP4rev1 is desired. 7295 15. Removed the CHECK command. Clients should use NOOP instead. 7297 16. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7298 deprecated. Clients should use the corresponding BODY[] 7299 variants instead. 7301 17. LSUB command was deprecated. Clients should use LIST 7302 (SUBSCRIBED) instead. 7304 18. IDLE command can now return updates not related to the currently 7305 selected mailbox state. 7307 19. All unsolicited FETCH updates are required to include UID. 7309 20. Clarified that client implementations MUST ignore response codes 7310 that they do not recognize. (Change from a SHOULD to a MUST.) 7312 21. resp-text ABNF non terminal was updated to allow for empty text. 7314 22. After ENABLE IMAP4rev2 human readable response text can include 7315 non ASCII encoded in UTF-8. 7317 23. Updated to use modern TLS-related recommendations as per RFC 7318 8314, RFC 7817, RFC 7525. 7320 24. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7321 MD5 was deprecated. 7323 Appendix F. Other Recommended IMAP Extensions 7325 Support for the following extensions is recommended for all IMAP 7326 client and servers. Why they significantly reduce bandwidth and/or 7327 number of round trips used by IMAP in certain situations, the EXTRA 7328 WG decided that requiring them as a part of IMAP4rev2 would push the 7329 bar to implement too high for new implementations. Also note that 7330 absence of any IMAP extension from this list doesn't make it somehow 7331 deficient or not recommended for use with IMAP4rev2. 7333 1. QRESYNC and CONDSTORE extensions (RFC 7162). They make 7334 discovering changes to IMAP mailboxes more efficient, at the 7335 expense of storing a bit more state. 7337 2. OBJECTID extension (RFC 8474) helps with preserving IMAP client 7338 cache when messages moved/copied or mailboxes are renamed. 7340 Appendix G. Acknowledgement 7342 Earlier versions of this document were edited by Mark Crispin. 7343 Sadly, he is no longer available to help with this work. Editors of 7344 this revisions are hoping that Mark would have approved. 7346 Chris Newman has contributed text on I18N and use of UTF-8 in 7347 messages and mailbox names. 7349 Thank you to Tony Hansen for helping with the index generation. 7350 Thank you to Murray Kucherawy, Timo Sirainen, Bron Gondwana, Stephan 7351 Bosch and Arnt Gulbrandsen for extensive feedback. 7353 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7354 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7355 Gulbrandsen), RFC 5465 (by Arnt Gulbrandsen and Curtis King), RFC 7356 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo Sirainen), RFC 6154 (by 7357 Jamie Nicolson), RFC 8438 (by Stephan Bosch) so work done by authors/ 7358 editors of these documents is appreciated. Note that editors of this 7359 document were redacted from the above list. 7361 The CHILDREN return option was originally proposed by Mike Gahrns and 7362 Raymond Cheng in [RFC3348]. Most of the information in 7363 Section 6.3.9.5 is taken directly from their original specification 7364 [RFC3348]. 7366 Thank you to Damian Poddebniak for pointing out that the ENABLE 7367 command should be a member of "command-auth" and not "command-any" 7368 ABNF production. 7370 Index 7372 $ 7373 $Forwarded (predefined flag) 12 7374 $Junk (predefined flag) 12 7375 $MDNSent (predefined flag) 12 7376 $NotJunk (predefined flag) 13 7377 $Phishing (predefined flag) 13 7379 + 7380 +FLAGS 92 7381 +FLAGS.SILENT 92 7383 - 7384 -FLAGS 92 7385 -FLAGS.SILENT 92 7387 A 7388 ALERT (response code) 99 7389 ALL (fetch item) 88 7390 ALL (search key) 78 7391 ALL (search result option) 76 7392 ALREADYEXISTS (response code) 99 7393 ANSWERED (search key) 78 7394 APPEND (command) 68 7395 APPENDUID (response code) 100 7396 AUTHENTICATE (command) 29 7397 AUTHENTICATIONFAILED (response code) 100 7398 AUTHORIZATIONFAILED (response code) 101 7400 B 7401 BAD (response) 108 7402 BADCHARSET (response code) 101 7403 BCC (search key) 78 7404 BEFORE (search key) 78 7405 BINARY.PEEK[]<> (fetch item) 88 7406 BINARY.SIZE[] (fetch item) 89 7407 BINARY.SIZE[] (fetch result) 118 7408 BINARY[]<> (fetch result) 118 7409 BINARY[]<> (fetch item) 88 7410 BODY (fetch item) 89 7411 BODY (fetch result) 119 7412 BODY (search key) 78 7413 BODY.PEEK[
]<> (fetch item) 89 7414 BODYSTRUCTURE (fetch item) 90 7415 BODYSTRUCTURE (fetch result) 119 7416 BODY[
]<> (fetch result) 119 7417 BODY[
]<> (fetch item) 89 7418 BYE (response) 109 7419 Body Structure (message attribute) 14 7421 C 7422 CANNOT (response code) 101 7423 CAPABILITY (command) 25 7424 CAPABILITY (response code) 101 7425 CAPABILITY (response) 110 7426 CC (search key) 78 7427 CLIENTBUG (response code) 101 7428 CLOSE (command) 74 7429 CLOSED (response code) 102 7430 CONTACTADMIN (response code) 102 7431 COPY (command) 93 7432 COPYUID (response code) 102 7433 CORRUPTION (response code) 103 7434 COUNT (search result option) 76 7435 CREATE (command) 38 7437 D 7438 DELETE (command) 39 7439 DELETED (search key) 78 7440 DELETED (status item) 68 7441 DRAFT (search key) 78 7443 E 7444 ENABLE (command) 33 7445 ENVELOPE (fetch item) 90 7446 ENVELOPE (fetch result) 122 7447 ESEARCH (response) 115 7448 EXAMINE (command) 37 7449 EXPIRED (response code) 103 7450 EXPUNGE (command) 75 7451 EXPUNGE (response) 117 7452 EXPUNGEISSUED (response code) 103 7453 Envelope Structure (message attribute) 14 7455 F 7456 FAST (fetch item) 88 7457 FETCH (command) 87 7458 FETCH (response) 118 7459 FLAGGED (search key) 78 7460 FLAGS (fetch item) 90 7461 FLAGS (fetch result) 123 7462 FLAGS (response) 116 7463 FLAGS (store command data item) 92 7464 FLAGS.SILENT (store command data item) 92 7465 FROM (search key) 78 7466 FULL (fetch item) 88 7467 Flags (message attribute) 11 7469 H 7470 HASCHILDREN (response code) 103 7471 HEADER (part specifier) 90 7472 HEADER (search key) 79 7473 HEADER.FIELDS (part specifier) 90 7474 HEADER.FIELDS.NOT (part specifier) 90 7476 I 7477 IDLE (command) 71 7478 INTERNALDATE (fetch item) 90 7479 INTERNALDATE (fetch result) 123 7480 INUSE (response code) 104 7481 Internal Date (message attribute) 13 7483 K 7484 KEYWORD (search key) 79 7485 Keyword (type of flag) 12 7487 L 7488 LARGER (search key) 79 7489 LIMIT (response code) 104 7490 LIST (command) 44 7491 LIST (response) 111 7492 LOGOUT (command) 27 7494 M 7495 MAX (search result option) 76 7496 MAY (specification requirement term) 5 7497 MESSAGES (status item) 68 7498 MIME (part specifier) 91 7499 MIN (search result option) 76 7500 MOVE (command) 94 7501 MUST (specification requirement term) 5 7502 MUST NOT (specification requirement term) 5 7503 Message Sequence Number (message attribute) 11 7505 N 7506 NAMESPACE (command) 63 7507 NAMESPACE (response) 115 7508 NO (response) 108 7509 NONEXISTENT (response code) 104 7510 NOOP (command) 26 7511 NOPERM (response code) 104 7512 NOT (search key) 79 7513 NOT RECOMMENDED (specification requirement term) 5 7515 O 7516 OK (response) 107 7517 ON (search key) 79 7518 OPTIONAL (specification requirement term) 5 7519 OR (search key) 79 7520 OVERQUOTA (response code) 104 7522 P 7523 PARSE (response code) 105 7524 PERMANENTFLAGS (response code) 105 7525 PREAUTH (response) 108 7526 PRIVACYREQUIRED (response code) 105 7527 Permanent Flag (class of flag) 13 7528 Predefined keywords 12 7530 R 7531 READ-ONLY (response code) 106 7532 READ-WRITE (response code) 106 7533 RECOMMENDED (specification requirement term) 5 7534 RENAME (command) 41 7535 REQUIRED (specification requirement term) 5 7536 RFC822.SIZE (fetch item) 90 7537 RFC822.SIZE (fetch result) 123 7539 S 7540 SAVE (search result option) 76 7541 SEARCH (command) 75 7542 SEEN (search key) 79 7543 SELECT (command) 35 7544 SENTBEFORE (search key) 79 7545 SENTON (search key) 79 7546 SENTSINCE (search key) 79 7547 SERVERBUG (response code) 106 7548 SHOULD (specification requirement term) 5 7549 SHOULD NOT (specification requirement term) 5 7550 SINCE (search key) 79 7551 SIZE (status item) 68 7552 SMALLER (search key) 79 7553 STARTTLS (command) 28 7554 STATUS (command) 67 7555 STATUS (response) 115 7556 STORE (command) 92 7557 SUBJECT (search key) 79 7558 SUBSCRIBE (command) 43 7559 Session Flag (class of flag) 13 7560 System Flag (type of flag) 12 7562 T 7563 TEXT (part specifier) 90 7564 TEXT (search key) 80 7565 TO (search key) 80 7566 TRYCREATE (response code) 106 7568 U 7569 UID (command) 96 7570 UID (fetch item) 90 7571 UID (fetch result) 123 7572 UID (search key) 80 7573 UIDNEXT (response code) 106 7574 UIDNEXT (status item) 68 7575 UIDNOTSTICKY (response code) 106 7576 UIDVALIDITY (response code) 107 7577 UIDVALIDITY (status item) 68 7578 UNANSWERED (search key) 80 7579 UNAVAILABLE (response code) 107 7580 UNDELETED (search key) 80 7581 UNDRAFT (search key) 80 7582 UNFLAGGED (search key) 80 7583 UNKEYWORD (search key) 80 7584 UNKNOWN-CTE (response code) 107 7585 UNSEEN (search key) 80 7586 UNSEEN (status item) 68 7587 UNSELECT (command) 74 7588 UNSUBSCRIBE (command) 44 7589 Unique Identifier (UID) (message attribute) 9 7591 X 7592 X (command) 97 7594 [ 7595 [RFC-5322] Size (message attribute) 14 7597 \ 7598 \All (mailbox name attribute) 113 7599 \Answered (system flag) 12 7600 \Archive (mailbox name attribute) 113 7601 \Deleted (system flag) 12 7602 \Draft (system flag) 12 7603 \Drafts (mailbox name attribute) 113 7604 \Flagged (mailbox name attribute) 113 7605 \Flagged (system flag) 12 7606 \HasChildren (mailbox name attribute) 112 7607 \HasNoChildren (mailbox name attribute) 112 7608 \Junk (mailbox name attribute) 113 7609 \Marked (mailbox name attribute) 112 7610 \Noinferiors (mailbox name attribute) 111 7611 \NonExistent (mailbox name attribute) 111 7612 \Noselect (mailbox name attribute) 111 7613 \Recent (system flag) 12 7614 \Remote (mailbox name attribute) 112 7615 \Seen (system flag) 12 7616 \Sent (mailbox name attribute) 113 7617 \Subscribed (mailbox name attribute) 112 7618 \Trash (mailbox name attribute) 113 7619 \Unmarked (mailbox name attribute) 112 7621 Authors' Addresses 7623 Alexey Melnikov (editor) 7624 Isode Ltd 7625 14 Castle Mews 7626 Hampton, Middlesex TW12 2NP 7627 UK 7629 Email: Alexey.Melnikov@isode.com 7631 Barry Leiba (editor) 7632 Futurewei Technologies 7634 Phone: +1 646 827 0648 7635 Email: barryleiba@computer.org 7636 URI: http://internetmessagingtechnology.org/