idnits 2.17.1 draft-ietf-extra-imap4rev2-15.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an Introduction section. ** There are 2 instances of too long lines in the document, the longest one being 2 characters in excess of 72. -- The draft header indicates that this document obsoletes RFC3501, but the abstract doesn't seem to mention this, which it should. 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 (June 17, 2020) is 1406 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. 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 6866, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 6861, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 6851, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 6856, but not defined == Missing Reference: 'RFC-822' is mentioned on line 6870, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 6800, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 6789, but not defined == Missing Reference: 'RFC3503' is mentioned on line 6761, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 6829, but not defined == Missing Reference: 'SMTP' is mentioned on line 6810, but not defined == Missing Reference: 'RFC7888' is mentioned on line 6785, but not defined -- Looks like a reference, but probably isn't: '1' on line 881 == Missing Reference: 'IMAP-URL' is mentioned on line 6824, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5632, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1714, but not defined == Missing Reference: 'RFC5258' is mentioned on line 6991, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6776, but not defined == Missing Reference: 'RFC3348' is mentioned on line 6780, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 6817, but not defined == Missing Reference: 'RFC3501' is mentioned on line 6847, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3165, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3236, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 6839, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 6794, but not defined == Missing Reference: 'HEADER' is mentioned on line 5649, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3806, but not defined == Missing Reference: 'UID' is mentioned on line 4216, but not defined == Missing Reference: 'RFC2087' is mentioned on line 6821, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 6834, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5633, but not defined == Missing Reference: 'RFC4422' is mentioned on line 5976, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6061, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6127, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 6874, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6766, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 6892, but not defined == Missing Reference: 'RFC3516' is mentioned on line 6982, but not defined ** Obsolete normative reference: RFC 5246 (ref. 'TLS') (Obsoleted by RFC 8446) ** 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: 10 errors (**), 0 flaws (~~), 38 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: December 19, 2020 June 17, 2020 8 Internet Message Access Protocol (IMAP) - Version 4rev2 9 draft-ietf-extra-imap4rev2-15 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 RFC 6409. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at https://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on December 19, 2020. 48 Copyright Notice 50 Copyright (c) 2020 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (https://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 This document may contain material from IETF Documents or IETF 64 Contributions published or made publicly available before November 65 10, 2008. The person(s) controlling the copyright in some of this 66 material may not have granted the IETF Trust the right to allow 67 modifications of such material outside the IETF Standards Process. 68 Without obtaining an adequate license from the person(s) controlling 69 the copyright in such materials, this document may not be modified 70 outside the IETF Standards Process, and derivative works of it may 71 not be created outside the IETF Standards Process, except to format 72 it for publication as an RFC or to translate it into languages other 73 than English. 75 Table of Contents 77 1. How to Read This Document . . . . . . . . . . . . . . . . . . 5 78 1.1. Organization of This Document . . . . . . . . . . . . . . 5 79 1.2. Conventions Used in This Document . . . . . . . . . . . . 5 80 1.3. Special Notes to Implementors . . . . . . . . . . . . . . 6 81 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 82 2.1. Link Level . . . . . . . . . . . . . . . . . . . . . . . 7 83 2.2. Commands and Responses . . . . . . . . . . . . . . . . . 7 84 2.2.1. Client Protocol Sender and Server Protocol Receiver . 7 85 2.2.2. Server Protocol Sender and Client Protocol Receiver . 8 86 2.3. Message Attributes . . . . . . . . . . . . . . . . . . . 9 87 2.3.1. Message Numbers . . . . . . . . . . . . . . . . . . . 9 88 2.3.2. Flags Message Attribute . . . . . . . . . . . . . . . 11 89 2.3.3. Internal Date Message Attribute . . . . . . . . . . . 13 90 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 13 91 2.3.5. Envelope Structure Message Attribute . . . . . . . . 14 92 2.3.6. Body Structure Message Attribute . . . . . . . . . . 14 93 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 14 94 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 14 95 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 14 96 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 14 97 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 15 98 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 15 99 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 17 100 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 17 101 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 17 102 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 17 103 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 17 104 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 18 105 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 19 106 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 107 5. Operational Considerations . . . . . . . . . . . . . . . . . 20 108 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 20 109 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 21 110 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 21 111 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 23 112 5.3. Response when no Command in Progress . . . . . . . . . . 23 113 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 23 114 5.5. Multiple Commands in Progress (Command Pipelining) . . . 23 115 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 116 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 25 117 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 25 118 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 26 119 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 120 6.2. Client Commands - Not Authenticated State . . . . . . . . 27 121 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 28 122 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 29 123 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 32 124 6.3. Client Commands - Authenticated State . . . . . . . . . . 33 125 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 33 126 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 35 127 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 37 128 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 38 129 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 39 130 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 40 131 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 42 132 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 43 133 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 43 134 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 61 135 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 65 136 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 66 137 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 69 138 6.4. Client Commands - Selected State . . . . . . . . . . . . 71 139 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 71 140 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 72 141 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 72 142 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 73 143 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 85 144 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 89 145 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 90 146 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 91 147 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 93 148 6.5. Client Commands - Experimental/Expansion . . . . . . . . 95 149 6.5.1. X Command . . . . . . . . . . . . . . . . . . . 95 150 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 96 151 7.1. Server Responses - Status Responses . . . . . . . . . . . 97 152 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 105 153 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 105 154 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 106 155 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 106 156 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 106 157 7.2. Server Responses - Server and Mailbox Status . . . . . . 107 158 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 107 159 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 107 160 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 108 161 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 112 162 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 113 163 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 113 164 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 113 165 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 114 166 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 114 167 7.4. Server Responses - Message Status . . . . . . . . . . . . 114 168 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 114 169 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 115 170 7.5. Server Responses - Command Continuation Request . . . . . 121 171 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 122 172 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 123 173 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 140 174 11. Security Considerations . . . . . . . . . . . . . . . . . . . 140 175 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 140 176 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 140 177 11.3. LIST command and Other Users' namespace . . . . . . . . 141 178 11.4. Other Security Considerations . . . . . . . . . . . . . 141 179 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 142 180 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 142 181 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 142 182 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 142 183 13.1. Normative References . . . . . . . . . . . . . . . . . . 142 184 13.2. Informative References (related protocols) . . . . . . . 145 185 13.3. Informative References (historical aspects of IMAP and 186 related protocols) . . . . . . . . . . . . . . . . . . . 147 187 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 148 188 A.1. Mailbox International Naming Convention for compatibility 189 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 148 190 Appendix B. Backward compatibility with BINARY extension . . . . 150 191 Appendix C. Backward compatibility with LIST-EXTENDED extension 150 192 Appendix D. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 150 193 Appendix E. Acknowledgement . . . . . . . . . . . . . . . . . . 153 194 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 195 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 158 197 1. How to Read This Document 199 1.1. Organization of This Document 201 This document is written from the point of view of the implementor of 202 an IMAP4rev2 client or server. Beyond the protocol overview in 203 section 2, it is not optimized for someone trying to understand the 204 operation of the protocol. The material in sections 3 through 5 205 provides the general context and definitions with which IMAP4rev2 206 operates. 208 Sections 6, 7, and 9 describe the IMAP commands, responses, and 209 syntax, respectively. The relationships among these are such that it 210 is almost impossible to understand any of them separately. In 211 particular, do not attempt to deduce command syntax from the command 212 section alone; instead refer to the Formal Syntax section. 214 1.2. Conventions Used in This Document 216 "Conventions" are basic principles or procedures. Document 217 conventions are noted in this section. 219 In examples, "C:" and "S:" indicate lines sent by the client and 220 server respectively. 222 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 223 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 224 "OPTIONAL" in this document are to be interpreted as described in BCP 225 14 [RFC2119] [RFC8174] when, and only when, they appear in all 226 capitals, as shown here. 228 The word "can" (not "may") is used to refer to a possible 229 circumstance or situation, as opposed to an optional facility of the 230 protocol. 232 "User" is used to refer to a human user, whereas "client" refers to 233 the software being run by the user. 235 "Connection" refers to the entire sequence of client/server 236 interaction from the initial establishment of the network connection 237 until its termination. 239 "Session" refers to the sequence of client/server interaction from 240 the time that a mailbox is selected (SELECT or EXAMINE command) until 241 the time that selection ends (SELECT or EXAMINE of another mailbox, 242 CLOSE command, UNSELECT command, or connection termination). 244 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 245 unless otherwise specified. Other character sets are indicated using 246 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 247 CHARSETs have important additional semantics in addition to defining 248 character set; refer to these documents for more detail. 250 There are several protocol conventions in IMAP. These refer to 251 aspects of the specification which are not strictly part of the IMAP 252 protocol, but reflect generally-accepted practice. Implementations 253 need to be aware of these conventions, and avoid conflicts whether or 254 not they implement the convention. For example, "&" may not be used 255 as a hierarchy delimiter since it conflicts with the Mailbox 256 International Naming Convention, and other uses of "&" in mailbox 257 names are impacted as well. 259 1.3. Special Notes to Implementors 261 Implementors of the IMAP protocol are strongly encouraged to read the 262 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 263 conjunction with this document, to help understand the intricacies of 264 this protocol and how best to build an interoperable product. 266 IMAP4rev2 is designed to be upwards compatible from the [IMAP2] and 267 unpublished IMAP2bis protocols. IMAP4rev2 is largely compatible with 268 the IMAP4rev1 protocol described in RFC 3501 and the IMAP4 protocol 269 described in RFC 1730; the exception being in certain facilities 270 added in RFC 1730 that proved problematic and were subsequently 271 removed. In the course of the evolution of IMAP4rev2, some aspects 272 in the earlier protocols have become obsolete. Obsolete commands, 273 responses, and data formats which an IMAP4rev2 implementation can 274 encounter when used with an earlier implementation are described in 275 Appendix D and [IMAP-OBSOLETE]. 277 Other compatibility issues with IMAP2bis, the most common variant of 278 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 279 discussion of compatibility issues with rare (and presumed extinct) 280 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 281 primarily of historical interest. 283 IMAP was originally developed for the older [RFC-822] standard, and 284 as a consequence several fetch items in IMAP incorporate "RFC822" in 285 their name. In all cases, "RFC822" should be interpreted as a 286 reference to the updated [RFC-5322] standard. 288 2. Protocol Overview 290 2.1. Link Level 292 The IMAP4rev2 protocol assumes a reliable data stream such as that 293 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 294 port 143 or port 993 (IMAP-over-TLS). 296 2.2. Commands and Responses 298 An IMAP4rev2 connection consists of the establishment of a client/ 299 server network connection, an initial greeting from the server, and 300 client/server interactions. These client/server interactions consist 301 of a client command, server data, and a server completion result 302 response. 304 All interactions transmitted by client and server are in the form of 305 lines, that is, strings that end with a CRLF. The protocol receiver 306 of an IMAP4rev2 client or server is either reading a line, or is 307 reading a sequence of octets with a known count followed by a line. 309 2.2.1. Client Protocol Sender and Server Protocol Receiver 311 The client command begins an operation. Each client command is 312 prefixed with an identifier (typically a short alphanumeric string, 313 e.g., A0001, A0002, etc.) called a "tag". A different tag is 314 generated by the client for each command. (More formally: the client 315 SHOULD generate a unique tag for every command, but a server MUST 316 accept tag reuse.) 318 Clients MUST follow the syntax outlined in this specification 319 strictly. It is a syntax error to send a command with missing or 320 extraneous spaces or arguments. 322 There are two cases in which a line from the client does not 323 represent a complete command. In one case, a command argument is 324 quoted with an octet count (see the description of literal in String 325 under Data Formats); in the other case, the command arguments require 326 server feedback (see the AUTHENTICATE command). In either case, the 327 server sends a command continuation request response if it is ready 328 for the octets (if appropriate) and the remainder of the command. 329 This response is prefixed with the token "+". 331 Note: If instead, the server detected an error in the command, it 332 sends a BAD completion response with a tag matching the command 333 (as described below) to reject the command and prevent the client 334 from sending any more of the command. 336 It is also possible for the server to send a completion response 337 for some other command (if multiple commands are in progress), or 338 untagged data. In either case, the command continuation request 339 is still pending; the client takes the appropriate action for the 340 response, and reads another response from the server. In all 341 cases, the client MUST send a complete command (including 342 receiving all command continuation request responses and command 343 continuations for the command) before initiating a new command. 345 The protocol receiver of an IMAP4rev2 server reads a command line 346 from the client, parses the command and its arguments, and transmits 347 server data and a server command completion result response. 349 2.2.2. Server Protocol Sender and Client Protocol Receiver 351 Data transmitted by the server to the client and status responses 352 that do not indicate command completion are prefixed with the token 353 "*", and are called untagged responses. 355 Server data MAY be sent as a result of a client command, or MAY be 356 sent unilaterally by the server. There is no syntactic difference 357 between server data that resulted from a specific command and server 358 data that were sent unilaterally. 360 The server completion result response indicates the success or 361 failure of the operation. It is tagged with the same tag as the 362 client command which began the operation. Thus, if more than one 363 command is in progress, the tag in a server completion response 364 identifies the command to which the response applies. There are 365 three possible server completion responses: OK (indicating success), 366 NO (indicating failure), or BAD (indicating a protocol error such as 367 unrecognized command or command syntax error). 369 Servers SHOULD enforce the syntax outlined in this specification 370 strictly. Any client command with a protocol syntax error, including 371 (but not limited to) missing or extraneous spaces or arguments, 372 SHOULD be rejected, and the client given a BAD server completion 373 response. 375 The protocol receiver of an IMAP4rev2 client reads a response line 376 from the server. It then takes action on the response based upon the 377 first token of the response, which can be a tag, a "*", or a "+". 379 A client MUST be prepared to accept any server response at all times. 380 This includes server data that was not requested. Server data SHOULD 381 be recorded, so that the client can reference its recorded copy 382 rather than sending a command to the server to request the data. In 383 the case of certain server data, the data MUST be recorded. 385 This topic is discussed in greater detail in the Server Responses 386 section. 388 2.3. Message Attributes 390 In addition to message text, each message has several attributes 391 associated with it. These attributes can be retrieved individually 392 or in conjunction with other attributes or message texts. 394 2.3.1. Message Numbers 396 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 397 identifier or the message sequence number. 399 2.3.1.1. Unique Identifier (UID) Message Attribute 401 An unsigned non-zero 32-bit value assigned to each message, which 402 when used with the unique identifier validity value (see below) forms 403 a 64-bit value that MUST NOT refer to any other message in the 404 mailbox or any subsequent mailbox with the same name forever. Unique 405 identifiers are assigned in a strictly ascending fashion in the 406 mailbox; as each message is added to the mailbox it is assigned a 407 higher UID than the message(s) which were added previously. Unlike 408 message sequence numbers, unique identifiers are not necessarily 409 contiguous. 411 The unique identifier of a message MUST NOT change during the 412 session, and SHOULD NOT change between sessions. Any change of 413 unique identifiers between sessions MUST be detectable using the 414 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 415 are required for a client to resynchronize its state from a previous 416 session with the server (e.g., disconnected or offline access clients 417 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 419 Associated with every mailbox are two 32-bit unsigned non-zero values 420 which aid in unique identifier handling: the next unique identifier 421 value (UIDNEXT) and the unique identifier validity value 422 (UIDVALIDITY). 424 The next unique identifier value is the predicted value that will be 425 assigned to a new message in the mailbox. Unless the unique 426 identifier validity also changes (see below), the next unique 427 identifier value MUST have the following two characteristics. First, 428 the next unique identifier value MUST NOT change unless new messages 429 are added to the mailbox; and second, the next unique identifier 430 value MUST change whenever new messages are added to the mailbox, 431 even if those new messages are subsequently expunged. 433 Note: The next unique identifier value is intended to provide a 434 means for a client to determine whether any messages have been 435 delivered to the mailbox since the previous time it checked this 436 value. It is not intended to provide any guarantee that any 437 message will have this unique identifier. A client can only 438 assume, at the time that it obtains the next unique identifier 439 value, that messages arriving after that time will have a UID 440 greater than or equal to that value. 442 The unique identifier validity value is sent in a UIDVALIDITY 443 response code in an OK untagged response at mailbox selection time. 444 If unique identifiers from an earlier session fail to persist in this 445 session, the unique identifier validity value MUST be greater than 446 the one used in the earlier session. 448 Note: Ideally, unique identifiers SHOULD persist at all times. 449 Although this specification recognizes that failure to persist can 450 be unavoidable in certain server environments, it STRONGLY 451 ENCOURAGES message store implementation techniques that avoid this 452 problem. For example: 454 1. Unique identifiers MUST be strictly ascending in the mailbox 455 at all times. If the physical message store is re-ordered by 456 a non-IMAP agent, this requires that the unique identifiers in 457 the mailbox be regenerated, since the former unique 458 identifiers are no longer strictly ascending as a result of 459 the re-ordering. 461 2. If the message store has no mechanism to store unique 462 identifiers, it must regenerate unique identifiers at each 463 session, and each session must have a unique UIDVALIDITY 464 value. 466 3. If the mailbox is deleted and a new mailbox with the same name 467 is created at a later date, the server must either keep track 468 of unique identifiers from the previous instance of the 469 mailbox, or it must assign a new UIDVALIDITY value to the new 470 instance of the mailbox. A good UIDVALIDITY value to use in 471 this case is a 32-bit representation of the creation date/time 472 of the mailbox. It is alright to use a constant such as 1, 473 but only if it guaranteed that unique identifiers will never 474 be reused, even in the case of a mailbox being deleted (or 475 renamed) and a new mailbox by the same name created at some 476 future time. 478 4. The combination of mailbox name, UIDVALIDITY, and UID must 479 refer to a single immutable message on that server forever. 480 In particular, the internal date, [RFC-5322] size, envelope, 481 body structure, and message texts (all BODY[...] fetch data 482 items) must never change. This does not include message 483 numbers, nor does it include attributes that can be set by a 484 STORE command (e.g., FLAGS). 486 2.3.1.2. Message Sequence Number Message Attribute 488 A relative position from 1 to the number of messages in the mailbox. 489 This position MUST be ordered by ascending unique identifier. As 490 each new message is added, it is assigned a message sequence number 491 that is 1 higher than the number of messages in the mailbox before 492 that new message was added. 494 Message sequence numbers can be reassigned during the session. For 495 example, when a message is permanently removed (expunged) from the 496 mailbox, the message sequence number for all subsequent messages is 497 decremented. The number of messages in the mailbox is also 498 decremented. Similarly, a new message can be assigned a message 499 sequence number that was once held by some other message prior to an 500 expunge. 502 In addition to accessing messages by relative position in the 503 mailbox, message sequence numbers can be used in mathematical 504 calculations. For example, if an untagged "11 EXISTS" is received, 505 and previously an untagged "8 EXISTS" was received, three new 506 messages have arrived with message sequence numbers of 9, 10, and 11. 507 Another example, if message 287 in a 523 message mailbox has UID 508 12345, there are exactly 286 messages which have lesser UIDs and 236 509 messages which have greater UIDs. 511 2.3.2. Flags Message Attribute 513 A list of zero or more named tokens associated with the message. A 514 flag is set by its addition to this list, and is cleared by its 515 removal. There are two types of flags in IMAP4rev2. A flag of 516 either type can be permanent or session-only. 518 A system flag is a flag name that is pre-defined in this 519 specification and begin with "\". Certain system flags (\Deleted and 520 \Seen) have special semantics described elsewhere in this document. 521 The currently-defined system flags are: 523 \Seen Message has been read 525 \Answered Message has been answered 527 \Flagged Message is "flagged" for urgent/special attention 528 \Deleted Message is "deleted" for removal by later EXPUNGE 530 \Draft Message has not completed composition (marked as a draft). 532 \Recent This flag was in used in IMAP4rev1 and is now deprecated. 534 A keyword is defined by the server implementation. Keywords do not 535 begin with "\". Servers MAY permit the client to define new keywords 536 in the mailbox (see the description of the PERMANENTFLAGS response 537 code for more information). Some keywords that start with "$" are 538 also defined in this specification. 540 This document defines several keywords that were not originally 541 defined in RFC 3501, but which were found to be useful by client 542 implementations. These keywords SHOULD be supported (i.e. allowed in 543 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 544 server implementations: 546 $Forwarded Message has been forwarded to another email address, 547 embedded within or attached to a new message. An email client 548 sets this keyword when it successfully forwards the message to 549 another email address. Typical usage of this keyword is to show a 550 different (or additional) icon for a message that has been 551 forwarded. Once set, the flag SHOULD NOT be cleared. 553 $MDNSent Message Disposition Notification [RFC8098] was generated 554 and sent for this message. See [RFC3503] for more details on how 555 this keyword is used. 557 $Junk The user (or a delivery agent on behalf of the user) may 558 choose to mark a message as definitely containing junk ($Junk; see 559 also the related keyword $NotJunk). The $Junk keyword can be used 560 to mark (and potentially move/delete messages later), group or 561 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 562 information. 564 $NotJunk The user (or a delivery agent on behalf of the user) may 565 choose to mark a message as definitely not containing junk 566 ($NotJunk; see also the related keyword $Junk). The $NotJunk 567 keyword can be used to mark, group or show messages that the user 568 wants to see. See [IMAP-KEYWORDS-REG] for more information. 570 $Phishing The $Phishing keyword can be used by a delivery agent to 571 mark a message as highly likely to be a phishing email. An email 572 that's determined to be a phishing email by the delivery agent 573 should also be considered a junk email and have the appropriate 574 junk filtering applied, including setting the $Junk flag and 575 placing in the \Junk special-use mailbox if available. 577 If both the $Phishing flag and the $Junk flag are set, the user 578 agent should display an additional warning message to the user. 579 User agents should not use the term "phishing" in their warning 580 message as most users do not understand this term. Phrasing of 581 the form "this message may be trying to steal your personal 582 information" is recommended. Additionally the user agent may 583 display a warning when clicking on any hyperlinks within the 584 message. 585 The requirement for both $Phishing and $Junk to be set before a 586 user agent displays a warning is for better backwards 587 compatibility with existing clients that understand the $Junk flag 588 but not the $Phishing flag. This so that when an unextended 589 client removes the $Junk flag, an extended client will also show 590 the correct state. See [IMAP-KEYWORDS-REG] for more information. 592 $Junk and $NotJunk are mutually exclusive. If more than one of them 593 is set for a message, the client MUST treat this as if none of them 594 is set and SHOULD unset both of them on the IMAP server. 596 Other registered keywords can be found in the "IMAP and JMAP 597 Keywords" registry [IMAP-KEYWORDS-REG]. 599 A flag can be permanent or session-only on a per-flag basis. 600 Permanent flags are those which the client can add or remove from the 601 message flags permanently; that is, concurrent and subsequent 602 sessions will see any change in permanent flags. Changes to session 603 flags are valid only in that session. 605 2.3.3. Internal Date Message Attribute 607 The internal date and time of the message on the server. This is not 608 the date and time in the [RFC-5322] header, but rather a date and 609 time which reflects when the message was received. In the case of 610 messages delivered via [SMTP], this SHOULD be the date and time of 611 final delivery of the message as defined by [SMTP]. In the case of 612 messages delivered by the IMAP4rev2 COPY or MOVE command, this SHOULD 613 be the internal date and time of the source message. In the case of 614 messages delivered by the IMAP4rev2 APPEND command, this SHOULD be 615 the date and time as specified in the APPEND command description. 616 All other cases are implementation defined. 618 2.3.4. [RFC-5322] Size Message Attribute 620 The number of octets in the message, as expressed in [RFC-5322] 621 format. 623 2.3.5. Envelope Structure Message Attribute 625 A parsed representation of the [RFC-5322] header of the message. 626 Note that the IMAP Envelope structure is not the same as an [SMTP] 627 envelope. 629 2.3.6. Body Structure Message Attribute 631 A parsed representation of the [MIME-IMB] body structure information 632 of the message. 634 2.4. Message Texts 636 In addition to being able to fetch the full [RFC-5322] text of a 637 message, IMAP4rev2 permits the fetching of portions of the full 638 message text. Specifically, it is possible to fetch the [RFC-5322] 639 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 640 [MIME-IMB] header. 642 3. State and Flow Diagram 644 Once the connection between client and server is established, an 645 IMAP4rev2 connection is in one of four states. The initial state is 646 identified in the server greeting. Most commands are only valid in 647 certain states. It is a protocol error for the client to attempt a 648 command while the connection is in an inappropriate state, and the 649 server will respond with a BAD or NO (depending upon server 650 implementation) command completion result. 652 3.1. Not Authenticated State 654 In the not authenticated state, the client MUST supply authentication 655 credentials before most commands will be permitted. This state is 656 entered when a connection starts unless the connection has been pre- 657 authenticated. 659 3.2. Authenticated State 661 In the authenticated state, the client is authenticated and MUST 662 select a mailbox to access before commands that affect messages will 663 be permitted. This state is entered when a pre-authenticated 664 connection starts, when acceptable authentication credentials have 665 been provided, after an error in selecting a mailbox, or after a 666 successful CLOSE command. 668 3.3. Selected State 670 In a selected state, a mailbox has been selected to access. This 671 state is entered when a mailbox has been successfully selected. 673 3.4. Logout State 675 In the logout state, the connection is being terminated. This state 676 can be entered as a result of a client request (via the LOGOUT 677 command) or by unilateral action on the part of either the client or 678 server. 680 If the client requests the logout state, the server MUST send an 681 untagged BYE response and a tagged OK response to the LOGOUT command 682 before the server closes the connection; and the client MUST read the 683 tagged OK response to the LOGOUT command before the client closes the 684 connection. 686 A server SHOULD NOT unilaterally close the connection without sending 687 an untagged BYE response that contains the reason for having done so. 688 A client SHOULD NOT unilaterally close the connection, and instead 689 SHOULD issue a LOGOUT command. If the server detects that the client 690 has unilaterally closed the connection, the server MAY omit the 691 untagged BYE response and simply close its connection. 693 +----------------------+ 694 |connection established| 695 +----------------------+ 696 || 697 \/ 698 +--------------------------------------+ 699 | server greeting | 700 +--------------------------------------+ 701 || (1) || (2) || (3) 702 \/ || || 703 +-----------------+ || || 704 |Not Authenticated| || || 705 +-----------------+ || || 706 || (7) || (4) || || 707 || \/ \/ || 708 || +----------------+ || 709 || | Authenticated |<=++ || 710 || +----------------+ || || 711 || || (7) || (5) || (6) || 712 || || \/ || || 713 || || +--------+ || || 714 || || |Selected|==++ || 715 || || +--------+ || 716 || || || (7) || 717 \/ \/ \/ \/ 718 +--------------------------------------+ 719 | Logout | 720 +--------------------------------------+ 721 || 722 \/ 723 +-------------------------------+ 724 |both sides close the connection| 725 +-------------------------------+ 727 (1) connection without pre-authentication (OK greeting) 728 (2) pre-authenticated connection (PREAUTH greeting) 729 (3) rejected connection (BYE greeting) 730 (4) successful LOGIN or AUTHENTICATE command 731 (5) successful SELECT or EXAMINE command 732 (6) CLOSE command, unsolicited CLOSED response code or 733 failed SELECT or EXAMINE command 734 (7) LOGOUT command, server shutdown, or connection closed 736 4. Data Formats 738 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 739 be in one of several forms: atom, number, string, parenthesized list, 740 or NIL. Note that a particular data item may take more than one 741 form; for example, a data item defined as using "astring" syntax may 742 be either an atom or a string. 744 4.1. Atom 746 An atom consists of one or more non-special characters. 748 4.1.1. Sequence set and UID set 750 A set of messages can be referenced by a sequence set containing 751 either message sequence numbers or unique identifiers. See Section 9 752 for details. Sequence sets can contain ranges (e.g. "5:50"), an 753 enumeration of specific message/UID numbers, a special symbol "*", or 754 a combination of the above. 756 A "UID set" is similar to the sequence set of unique identifiers; 757 however, the "*" value for a sequence number is not permitted. 759 4.2. Number 761 A number consists of one or more digit characters, and represents a 762 numeric value. 764 4.3. String 766 A string is in one of three forms: synchonizing literal, non- 767 synchronizing literal or quoted string. The synchronizing literal 768 form is the general form of string. The non-synchronizing literal 769 form is also the general form, but has length limitation. The quoted 770 string form is an alternative that avoids the overhead of processing 771 a literal at the cost of limitations of characters which may be used. 773 When the distinction between synchronizing and non-synchronizing 774 literals is not important, this document just uses the term 775 "literal". 777 A synchronizing literal is a sequence of zero or more octets 778 (including CR and LF), prefix-quoted with an octet count in the form 779 of an open brace ("{"), the number of octets, close brace ("}"), and 780 CRLF. In the case of synchronizing literals transmitted from server 781 to client, the CRLF is immediately followed by the octet data. In 782 the case of synchronizing literals transmitted from client to server, 783 the client MUST wait to receive a command continuation request 784 (described later in this document) before sending the octet data (and 785 the remainder of the command). 787 The non-synchronizing literal is an alternate form of synchronizing 788 literal, and it may appear in communication from client to server 789 instead of the synchonizing form of literal. The non-synchronizing 790 literal form MUST NOT be sent from server to client. The non- 791 synchronizing literal is distinguished from the synchronizing literal 792 by having a plus ("+") between the octet count and the closing brace 793 ("}"). The server does not generate a command continuation request 794 in response to a non-synchronizing literal, and clients are not 795 required to wait before sending the octets of a non- synchronizing 796 literal. Non-synchronizing literals MUST NOT be larger than 4096 797 octets. Any literal larger than 4096 bytes MUST be sent as a 798 synchronizing literal. (Non-synchronizing literals defined in this 799 document are the same as non-synchronizing literals defined by the 800 LITERAL- extension from [RFC7888]. See that document for details on 801 how to handle invalid non-synchronizing literals longer than 4096 802 octets and for interaction with other IMAP extensions.) 804 A quoted string is a sequence of zero or more Unicode characters, 805 excluding CR and LF, encoded in UTF-8, with double quote (<">) 806 characters at each end. 808 The empty string is represented as "" (a quoted string with zero 809 characters between double quotes), as {0} followed by CRLF (a 810 synchronizing literal with an octet count of 0) or as {0+} followed 811 by CRLF (a non-synchronizing literal with an octet count of 0). 813 Note: Even if the octet count is 0, a client transmitting a 814 synchronizing literal MUST wait to receive a command continuation 815 request. 817 4.3.1. 8-bit and Binary Strings 819 8-bit textual and binary mail is supported through the use of a 820 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 821 transmit 8-bit or multi-octet characters in literals, but SHOULD do 822 so only when the [CHARSET] is identified. 824 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 825 identified charset for header-field values with 8-bit content is 826 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 827 transmit [UTF-8] text in quoted-strings as long as the string does 828 not contain NUL, CR, or LF. This differs from IMAP4rev1 829 implementations. 831 Although a BINARY content transfer encoding is defined, unencoded 832 binary strings are not permitted, unless returned in a in 833 response to BINARY.PEEK[]<> or 834 BINARY[]<> FETCH data item. A "binary 835 string" is any string with NUL characters. A string with an 836 excessive amount of CTL characters MAY also be considered to be 837 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 838 FETCH, client and server implementations MUST encode binary data into 839 a textual form, such as BASE64, before transmitting the data. 841 4.4. Parenthesized List 843 Data structures are represented as a "parenthesized list"; a sequence 844 of data items, delimited by space, and bounded at each end by 845 parentheses. A parenthesized list can contain other parenthesized 846 lists, using multiple levels of parentheses to indicate nesting. 848 The empty list is represented as () -- a parenthesized list with no 849 members. 851 4.5. NIL 853 The special form "NIL" represents the non-existence of a particular 854 data item that is represented as a string or parenthesized list, as 855 distinct from the empty string "" or the empty parenthesized list (). 857 Note: NIL is never used for any data item which takes the form of 858 an atom. For example, a mailbox name of "NIL" is a mailbox named 859 NIL as opposed to a non-existent mailbox name. This is because 860 mailbox uses "astring" syntax which is an atom or a string. 861 Conversely, an addr-name of NIL is a non-existent personal name, 862 because addr-name uses "nstring" syntax which is NIL or a string, 863 but never an atom. 865 Examples: 867 The following LIST response: 869 * LIST () "/" NIL 871 is equivalent to: 872 * LIST () "/" "NIL" 874 as LIST response ABNF is using astring for mailbox name. 876 However, the following response 878 * FETCH 1 (BODY[1] NIL) 880 is not equivalent to: 881 * FETCH 1 (BODY[1] "NIL") 882 The former means absence of the body part, while the latter 883 means that it contains literal sequence of characters "NIL". 885 5. Operational Considerations 887 The following rules are listed here to ensure that all IMAP4rev2 888 implementations interoperate properly. 890 5.1. Mailbox Naming 892 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 893 (this differs from IMAP4rev1). Client implementations MAY attempt to 894 create Net-Unicode mailbox names, and MUST interpret any 8-bit 895 mailbox names returned by LIST as [NET-UNICODE]. Server 896 implementations MUST prohibit the creation of 8-bit mailbox names 897 that do not comply with Net-Unicode. However, servers MAY accept a 898 de-normalized UTF-8 mailbox name and convert it to Unicode 899 normalization form "NFC" (as per Net-Unicode requirements) prior to 900 mailbox creation. Servers that choose to accept such de-normalized 901 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 902 mailbox name parameter. In particular SELECT must open the 903 same mailbox that was successfully created with CREATE , even 904 if is a de-normalized UTF-8 mailbox name. 906 The case-insensitive mailbox name INBOX is a special name reserved to 907 mean "the primary mailbox for this user on this server". (Note that 908 this special name may not exist on some servers for some users, for 909 example if the user has no access to personal namespace.) The 910 interpretation of all other names is implementation-dependent. 912 In particular, this specification takes no position on case 913 sensitivity in non-INBOX mailbox names. Some server implementations 914 are fully case-sensitive in ASCII range; others preserve case of a 915 newly-created name but otherwise are case-insensitive; and yet others 916 coerce names to a particular case. Client implementations must be 917 able to interact with any of these. 919 There are certain client considerations when creating a new mailbox 920 name: 922 1. Any character which is one of the atom-specials (see the Formal 923 Syntax) will require that the mailbox name be represented as a 924 quoted string or literal. 926 2. CTL and other non-graphic characters are difficult to represent 927 in a user interface and are best avoided. Servers MAY refuse to 928 create mailbox names containing Unicode CTL characters. 930 3. Although the list-wildcard characters ("%" and "*") are valid in 931 a mailbox name, it is difficult to use such mailbox names with 932 the LIST command due to the conflict with wildcard 933 interpretation. 935 4. Usually, a character (determined by the server implementation) is 936 reserved to delimit levels of hierarchy. 938 5. Two characters, "#" and "&", have meanings by convention, and 939 should be avoided except when used in that convention. 941 5.1.1. Mailbox Hierarchy Naming 943 If it is desired to export hierarchical mailbox names, mailbox names 944 MUST be left-to-right hierarchical using a single character to 945 separate levels of hierarchy. The same hierarchy separator character 946 is used for all levels of hierarchy within a single name. 948 5.1.2. Namespaces 950 Personal Namespace: A namespace that the server considers within the 951 personal scope of the authenticated user on a particular connection. 952 Typically, only the authenticated user has access to mailboxes in 953 their Personal Namespace. It is the part of the namespace that 954 belongs to the user that is allocated for mailboxes. If an INBOX 955 exists for a user, it MUST appear within the user's personal 956 namespace. In the typical case, there SHOULD be only one Personal 957 Namespace on a server. 959 Other Users' Namespace: A namespace that consists of mailboxes from 960 the Personal Namespaces of other users. To access mailboxes in the 961 Other Users' Namespace, the currently authenticated user MUST be 962 explicitly granted access rights. For example, it is common for a 963 manager to grant to their secretary access rights to their mailbox. 964 In the typical case, there SHOULD be only one Other Users' Namespace 965 on a server. 967 Shared Namespace: A namespace that consists of mailboxes that are 968 intended to be shared amongst users and do not exist within a user's 969 Personal Namespace. 971 The namespaces a server uses MAY differ on a per-user basis. 973 5.1.2.1. Historic Mailbox Namespace Naming Convention 975 By convention, the first hierarchical element of any mailbox name 976 which begins with "#" identifies the "namespace" of the remainder of 977 the name. This makes it possible to disambiguate between different 978 types of mailbox stores, each of which have their own namespaces. 980 For example, implementations which offer access to USENET 981 newsgroups MAY use the "#news" namespace to partition the USENET 982 newsgroup namespace from that of other mailboxes. Thus, the 983 comp.mail.misc newsgroup would have a mailbox name of 984 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 985 a different object (e.g., a user's private mailbox). 987 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 988 friendly requiring the "#" character to be represented as %23 when 989 within URLs. As such, server implementers MAY instead consider using 990 namespace prefixes that do not contain the "#" character. 992 5.1.2.2. Common namespace models 994 Previous version of this protocol does not define a default server 995 namespace. Two common namespace models have evolved: 997 The "Personal Mailbox" model, in which the default namespace that is 998 presented consists of only the user's personal mailboxes. To access 999 shared mailboxes, the user must use an escape mechanism to reach 1000 another namespace. 1002 The "Complete Hierarchy" model, in which the default namespace that 1003 is presented includes the user's personal mailboxes along with any 1004 other mailboxes they have access to. 1006 5.2. Mailbox Size and Message Status Updates 1008 At any time, a server can send data that the client did not request. 1009 Sometimes, such behavior is REQUIRED. For example, agents other than 1010 the server MAY add messages to the mailbox (e.g., new message 1011 delivery), change the flags of the messages in the mailbox (e.g., 1012 simultaneous access to the same mailbox by multiple agents), or even 1013 remove messages from the mailbox. A server MUST send mailbox size 1014 updates automatically if a mailbox size change is observed during the 1015 processing of a command. A server SHOULD send message flag updates 1016 automatically, without requiring the client to request such updates 1017 explicitly. 1019 Special rules exist for server notification of a client about the 1020 removal of messages to prevent synchronization errors; see the 1021 description of the EXPUNGE response for more detail. In particular, 1022 it is NOT permitted to send an EXISTS response that would reduce the 1023 number of messages in the mailbox; only the EXPUNGE response can do 1024 this. 1026 Regardless of what implementation decisions a client makes on 1027 remembering data from the server, a client implementation MUST record 1028 mailbox size updates. It MUST NOT assume that any command after the 1029 initial mailbox selection will return the size of the mailbox. 1031 5.3. Response when no Command in Progress 1033 Server implementations are permitted to send an untagged response 1034 (except for EXPUNGE) while there is no command in progress. Server 1035 implementations that send such responses MUST deal with flow control 1036 considerations. Specifically, they MUST either (1) verify that the 1037 size of the data does not exceed the underlying transport's available 1038 window size, or (2) use non-blocking writes. 1040 5.4. Autologout Timer 1042 If a server has an inactivity autologout timer that applies to 1043 sessions after authentication, the duration of that timer MUST be at 1044 least 30 minutes. The receipt of ANY command from the client during 1045 that interval SHOULD suffice to reset the autologout timer. 1047 5.5. Multiple Commands in Progress (Command Pipelining) 1049 The client MAY send another command without waiting for the 1050 completion result response of a command, subject to ambiguity rules 1051 (see below) and flow control constraints on the underlying data 1052 stream. Similarly, a server MAY begin processing another command 1053 before processing the current command to completion, subject to 1054 ambiguity rules. However, any command continuation request responses 1055 and command continuations MUST be negotiated before any subsequent 1056 command is initiated. 1058 The exception is if an ambiguity would result because of a command 1059 that would affect the results of other commands. If the server 1060 detects a possible ambiguity, it MUST execute commands to completion 1061 in the order given by the client. 1063 The most obvious example of ambiguity is when a command would affect 1064 the results of another command, e.g., a FETCH of a message's flags 1065 and a STORE of that same message's flags. 1067 A non-obvious ambiguity occurs with commands that permit an untagged 1068 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1069 since an untagged EXPUNGE response can invalidate sequence numbers in 1070 a subsequent command. This is not a problem for FETCH, STORE, or 1071 SEARCH commands because servers are prohibited from sending EXPUNGE 1072 responses while any of those commands are in progress. Therefore, if 1073 the client sends any command other than FETCH, STORE, or SEARCH, it 1074 MUST wait for the completion result response before sending a command 1075 with message sequence numbers. 1077 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1078 and UID SEARCH are in progress. If the client sends a UID 1079 command, it MUST wait for a completion result response before 1080 sending a command which uses message sequence numbers (this may 1081 include UID SEARCH). Any message sequence numbers in an argument 1082 to UID SEARCH are associated with messages prior to the effect of 1083 any untagged EXPUNGE returned by the UID SEARCH. 1085 For example, the following non-waiting command sequences are invalid: 1087 FETCH + NOOP + STORE 1089 STORE + COPY + FETCH 1091 COPY + COPY 1093 The following are examples of valid non-waiting command sequences: 1095 FETCH + STORE + SEARCH + NOOP 1097 STORE + COPY + EXPUNGE 1099 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1100 command sequence, depending upon whether or not the second UID 1101 SEARCH contains message sequence numbers. 1103 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1104 dependency between two commands. See Section 6.4.4.2 for more 1105 considerations about pipelining such dependent commands. 1107 6. Client Commands 1109 IMAP4rev2 commands are described in this section. Commands are 1110 organized by the state in which the command is permitted. Commands 1111 which are permitted in multiple states are listed in the minimum 1112 permitted state (for example, commands valid in authenticated and 1113 selected state are listed in the authenticated state commands). 1115 Command arguments, identified by "Arguments:" in the command 1116 descriptions below, are described by function, not by syntax. The 1117 precise syntax of command arguments is described in the Formal Syntax 1118 (Section 9). 1120 Some commands cause specific server responses to be returned; these 1121 are identified by "Responses:" in the command descriptions below. 1122 See the response descriptions in the Responses section for 1123 information on these responses, and the Formal Syntax section for the 1124 precise syntax of these responses. It is possible for server data to 1125 be transmitted as a result of any command. Thus, commands that do 1126 not specifically require server data specify "no specific responses 1127 for this command" instead of "none". 1129 The "Result:" in the command description refers to the possible 1130 tagged status responses to a command, and any special interpretation 1131 of these status responses. 1133 The state of a connection is only changed by successful commands 1134 which are documented as changing state. A rejected command (BAD 1135 response) never changes the state of the connection or of the 1136 selected mailbox. A failed command (NO response) generally does not 1137 change the state of the connection or of the selected mailbox; the 1138 exception being the SELECT and EXAMINE commands. 1140 6.1. Client Commands - Any State 1142 The following commands are valid in any state: CAPABILITY, NOOP, and 1143 LOGOUT. 1145 6.1.1. CAPABILITY Command 1147 Arguments: none 1149 Responses: REQUIRED untagged response: CAPABILITY 1150 Result: OK - capability completed 1151 BAD - command unknown or arguments invalid 1153 The CAPABILITY command requests a listing of capabilities that the 1154 server supports. The server MUST send a single untagged CAPABILITY 1155 response with "IMAP4rev2" as one of the listed capabilities before 1156 the (tagged) OK response. 1158 A capability name which begins with "AUTH=" indicates that the server 1159 supports that particular authentication mechanism. All such names 1160 are, by definition, part of this specification. For example, the 1161 authorization capability for an experimental "blurdybloop" 1162 authenticator would be "AUTH=XBLURDYBLOOP" and not 1163 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1165 Other capability names refer to extensions, revisions, or amendments 1166 to this specification. See the documentation of the CAPABILITY 1167 response for additional information. No capabilities, beyond the 1168 base IMAP4rev2 set defined in this specification, are enabled without 1169 explicit client action to invoke the capability. 1171 Client and server implementations MUST implement the STARTTLS, 1172 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1173 See the Security Considerations section for important information. 1175 See the section entitled "Client Commands - Experimental/Expansion" 1176 for information about the form of site or implementation-specific 1177 capabilities. 1179 Example: C: abcd CAPABILITY 1180 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1181 LOGINDISABLED 1182 S: abcd OK CAPABILITY completed 1183 C: efgh STARTTLS 1184 S: efgh OK STARTLS completed 1185 1186 C: ijkl CAPABILITY 1187 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1188 S: ijkl OK CAPABILITY completed 1190 6.1.2. NOOP Command 1192 Arguments: none 1194 Responses: no specific responses for this command (but see below) 1196 Result: OK - noop completed 1197 BAD - command unknown or arguments invalid 1199 The NOOP command always succeeds. It does nothing. 1201 Since any command can return a status update as untagged data, the 1202 NOOP command can be used as a periodic poll for new messages or 1203 message status updates during a period of inactivity (the IDLE 1204 command Section 6.3.13 should be used instead of NOOP if real-time 1205 updates to mailbox state are desirable). The NOOP command can also 1206 be used to reset any inactivity autologout timer on the server. 1208 Example: C: a002 NOOP 1209 S: a002 OK NOOP completed 1210 . . . 1211 C: a047 NOOP 1212 S: * 22 EXPUNGE 1213 S: * 23 EXISTS 1214 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1215 S: a047 OK NOOP completed 1217 6.1.3. LOGOUT Command 1219 Arguments: none 1221 Responses: REQUIRED untagged response: BYE 1223 Result: OK - logout completed 1224 BAD - command unknown or arguments invalid 1226 The LOGOUT command informs the server that the client is done with 1227 the connection. The server MUST send a BYE untagged response before 1228 the (tagged) OK response, and then close the network connection. 1230 Example: C: A023 LOGOUT 1231 S: * BYE IMAP4rev2 Server logging out 1232 S: A023 OK LOGOUT completed 1233 (Server and client then close the connection) 1235 6.2. Client Commands - Not Authenticated State 1237 In the not authenticated state, the AUTHENTICATE or LOGIN command 1238 establishes authentication and enters the authenticated state. The 1239 AUTHENTICATE command provides a general mechanism for a variety of 1240 authentication techniques, privacy protection, and integrity 1241 checking; whereas the LOGIN command uses a traditional user name and 1242 plaintext password pair and has no means of establishing privacy 1243 protection or integrity checking. 1245 The STARTTLS command is an alternate form of establishing session 1246 privacy protection and integrity checking, but does not by itself 1247 establish authentication or enter the authenticated state. 1249 Server implementations MAY allow access to certain mailboxes without 1250 establishing authentication. This can be done by means of the 1251 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1252 convention is a LOGIN command using the userid "anonymous"; in this 1253 case, a password is required although the server may choose to accept 1254 any password. The restrictions placed on anonymous users are 1255 implementation-dependent. 1257 Once authenticated (including as anonymous), it is not possible to 1258 re-enter not authenticated state. 1260 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1261 the following commands are valid in the not authenticated state: 1262 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1263 section for important information about these commands. 1265 6.2.1. STARTTLS Command 1267 Arguments: none 1269 Responses: no specific response for this command 1271 Result: OK - starttls completed, begin TLS negotiation 1272 BAD - command unknown or arguments invalid 1274 A [TLS] negotiation begins immediately after the CRLF at the end of 1275 the tagged OK response from the server. Once a client issues a 1276 STARTTLS command, it MUST NOT issue further commands until a server 1277 response is seen and the [TLS] negotiation is complete. 1279 The server remains in the non-authenticated state, even if client 1280 credentials are supplied during the [TLS] negotiation. This does not 1281 preclude an authentication mechanism such as EXTERNAL (defined in 1282 [SASL]) from using client identity determined by the [TLS] 1283 negotiation. 1285 Once [TLS] has been started, the client MUST discard cached 1286 information about server capabilities and SHOULD re-issue the 1287 CAPABILITY command. This is necessary to protect against man-in- 1288 the-middle attacks which alter the capabilities list prior to 1289 STARTTLS. The server MAY advertise different capabilities, and in 1290 particular SHOULD NOT advertise the STARTTLS capability, after a 1291 successful STARTTLS command. 1293 Example: C: a001 CAPABILITY 1294 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1295 S: a001 OK CAPABILITY completed 1296 C: a002 STARTTLS 1297 S: a002 OK Begin TLS negotiation now 1298 1299 C: a003 CAPABILITY 1300 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1301 S: a003 OK CAPABILITY completed 1302 C: a004 LOGIN joe password 1303 S: a004 OK LOGIN completed 1305 6.2.2. AUTHENTICATE Command 1307 Arguments: SASL authentication mechanism name 1308 OPTIONAL initial response 1310 Responses: continuation data can be requested 1312 Result: OK - authenticate completed, now in authenticated state 1313 NO - authenticate failure: unsupported authentication 1314 mechanism, credentials rejected 1315 BAD - command unknown or arguments invalid, 1316 authentication exchange cancelled 1318 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1319 to the server. If the server supports the requested authentication 1320 mechanism, it performs an authentication protocol exchange to 1321 authenticate and identify the client. It MAY also negotiate an 1322 OPTIONAL security layer for subsequent protocol interactions. If the 1323 requested authentication mechanism is not supported, the server 1324 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1325 response. 1327 The AUTHENTICATE command supports the optional "initial response" 1328 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1329 use it. If a SASL mechanism supports "initial response", but it is 1330 not specified by the client, the server handles this as specified in 1331 Section 3 of [SASL]. 1333 The service name specified by this protocol's profile of [SASL] is 1334 "imap". 1336 The authentication protocol exchange consists of a series of server 1337 challenges and client responses that are specific to the 1338 authentication mechanism. A server challenge consists of a command 1339 continuation request response with the "+" token followed by a BASE64 1340 encoded (see Section 4 of [RFC4648]) string. The client response 1341 consists of a single line consisting of a BASE64 encoded string. If 1342 the client wishes to cancel an authentication exchange, it issues a 1343 line consisting of a single "*". If the server receives such a 1344 response, or if it receives an invalid BASE64 string (e.g. 1345 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1346 reject the AUTHENTICATE command by sending a tagged BAD response. 1348 As with any other client response, this initial response MUST be 1349 encoded as BASE64. It also MUST be transmitted outside of a quoted 1350 string or literal. To send a zero-length initial response, the 1351 client MUST send a single pad character ("="). This indicates that 1352 the response is present, but is a zero-length string. 1354 When decoding the BASE64 data in the initial response, decoding 1355 errors MUST be treated as in any normal SASL client response, i.e. 1356 with a tagged BAD response. In particular, the server should check 1357 for any characters not explicitly allowed by the BASE64 alphabet, as 1358 well as any sequence of BASE64 characters that contains the pad 1359 character ('=') anywhere other than the end of the string (e.g., 1360 "=AAA" and "AAA=BBB" are not allowed). 1362 If the client uses an initial response with a SASL mechanism that 1363 does not support an initial response, the server MUST reject the 1364 command with a tagged BAD response. 1366 If a security layer is negotiated through the [SASL] authentication 1367 exchange, it takes effect immediately following the CRLF that 1368 concludes the authentication exchange for the client, and the CRLF of 1369 the tagged OK response for the server. 1371 While client and server implementations MUST implement the 1372 AUTHENTICATE command itself, it is not required to implement any 1373 authentication mechanisms other than the PLAIN mechanism described in 1374 [PLAIN]. Also, an authentication mechanism is not required to 1375 support any security layers. 1377 Note: a server implementation MUST implement a configuration in 1378 which it does NOT permit any plaintext password mechanisms, unless 1379 either the STARTTLS command has been negotiated or some other 1380 mechanism that protects the session from password snooping has 1381 been provided. Server sites SHOULD NOT use any configuration 1382 which permits a plaintext password mechanism without such a 1383 protection mechanism against password snooping. Client and server 1384 implementations SHOULD implement additional [SASL] mechanisms that 1385 do not use plaintext passwords, such the GSSAPI mechanism 1386 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1387 [SCRAM-SHA-256] mechanisms. 1389 Servers and clients can support multiple authentication mechanisms. 1390 The server SHOULD list its supported authentication mechanisms in the 1391 response to the CAPABILITY command so that the client knows which 1392 authentication mechanisms to use. 1394 A server MAY include a CAPABILITY response code in the tagged OK 1395 response of a successful AUTHENTICATE command in order to send 1396 capabilities automatically. It is unnecessary for a client to send a 1397 separate CAPABILITY command if it recognizes these automatic 1398 capabilities. This should only be done if a security layer was not 1399 negotiated by the AUTHENTICATE command, because the tagged OK 1400 response as part of an AUTHENTICATE command is not protected by 1401 encryption/integrity checking. [SASL] requires the client to re- 1402 issue a CAPABILITY command in this case. The server MAY advertise 1403 different capabilities after a successful AUTHENTICATE command. 1405 If an AUTHENTICATE command fails with a NO response, the client MAY 1406 try another authentication mechanism by issuing another AUTHENTICATE 1407 command. It MAY also attempt to authenticate by using the LOGIN 1408 command (see Section 6.2.3 for more detail). In other words, the 1409 client MAY request authentication types in decreasing order of 1410 preference, with the LOGIN command as a last resort. 1412 The authorization identity passed from the client to the server 1413 during the authentication exchange is interpreted by the server as 1414 the user name whose privileges the client is requesting. 1416 Example: S: * OK IMAP4rev2 Server 1417 C: A001 AUTHENTICATE GSSAPI 1418 S: + 1419 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1420 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1421 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1422 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1423 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1424 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1425 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1426 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1427 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1428 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1429 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1430 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1431 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1432 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1433 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1434 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1435 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1436 C: 1437 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1438 ceP2CWY0SR0fAQAgAAQEBAQ= 1439 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1440 wkhbfa2QteAQAgAG1yYwE= 1441 S: A001 OK GSSAPI authentication successful 1443 Note: The line breaks within server challenges and client responses 1444 are for editorial clarity and are not in real authenticators. 1446 6.2.3. LOGIN Command 1448 Arguments: user name 1449 password 1451 Responses: no specific responses for this command 1453 Result: OK - login completed, now in authenticated state 1454 NO - login failure: user name or password rejected 1455 BAD - command unknown or arguments invalid 1457 The LOGIN command identifies the client to the server and carries the 1458 plaintext password authenticating this user. 1460 A server MAY include a CAPABILITY response code in the tagged OK 1461 response to a successful LOGIN command in order to send capabilities 1462 automatically. It is unnecessary for a client to send a separate 1463 CAPABILITY command if it recognizes these automatic capabilities. 1465 Example: C: a001 LOGIN SMITH SESAME 1466 S: a001 OK LOGIN completed 1468 Note: Use of the LOGIN command over an insecure network (such as the 1469 Internet) is a security risk, because anyone monitoring network 1470 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1471 be used except as a last resort, and it is recommended that client 1472 implementations have a means to disable any automatic use of the 1473 LOGIN command. 1475 Unless either the client is accessing IMAP service on IMAPS port 1476 [RFC8314], the STARTTLS command has been negotiated or some other 1477 mechanism that protects the session from password snooping has been 1478 provided, a server implementation MUST implement a configuration in 1479 which it advertises the LOGINDISABLED capability and does NOT permit 1480 the LOGIN command. Server sites SHOULD NOT use any configuration 1481 which permits the LOGIN command without such a protection mechanism 1482 against password snooping. A client implementation MUST NOT send a 1483 LOGIN command if the LOGINDISABLED capability is advertised. 1485 6.3. Client Commands - Authenticated State 1487 In the authenticated state, commands that manipulate mailboxes as 1488 atomic entities are permitted. Of these commands, the SELECT and 1489 EXAMINE commands will select a mailbox for access and enter the 1490 selected state. 1492 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1493 the following commands are valid in the authenticated state: ENABLE, 1494 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1495 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1497 6.3.1. ENABLE Command 1499 Arguments: capability names 1501 Responses: no specific responses for this command 1503 Result: OK - Relevant capabilities enabled 1504 BAD - No arguments, or syntax error in an argument 1506 Several IMAP extensions allow the server to return unsolicited 1507 responses specific to these extensions in certain circumstances. 1508 However, servers cannot send those unsolicited responses (with the 1509 exception of response codes (see Section 7.1) included in tagged or 1510 untagged OK/NO/BAD responses, which can always be sent) until they 1511 know that the clients support such extensions and thus won't choke on 1512 the extension response data. 1514 The ENABLE command provides an explicit indication from the client 1515 that it supports particular extensions. It is designed such that the 1516 client can send a simple constant string with the extensions it 1517 supports, and the server will enable the shared subset that both 1518 support. 1520 The ENABLE command takes a list of capability names, and requests the 1521 server to enable the named extensions. Once enabled using ENABLE, 1522 each extension remains active until the IMAP connection is closed. 1523 For each argument, the server does the following: 1525 o If the argument is not an extension known to the server, the 1526 server MUST ignore the argument. 1528 o If the argument is an extension known to the server, and it is not 1529 specifically permitted to be enabled using ENABLE, the server MUST 1530 ignore the argument. (Note that knowing about an extension 1531 doesn't necessarily imply supporting that extension.) 1533 o If the argument is an extension that is supported by the server 1534 and that needs to be enabled, the server MUST enable the extension 1535 for the duration of the connection. Note that once an extension 1536 is enabled, there is no way to disable it. 1538 If the ENABLE command is successful, the server MUST send an untagged 1539 ENABLED response Section 7.2.1. 1541 Clients SHOULD only include extensions that need to be enabled by the 1542 server. For example, a client can enable IMAP4rev2 specific 1543 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1544 CAPABILITY response. Future RFCs may add to this list. 1546 The ENABLE command is only valid in the authenticated state, before 1547 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1548 SELECT/EXAMINE a mailbox; however, server implementations don't have 1549 to check that no mailbox is selected or was previously selected 1550 during the duration of a connection. 1552 The ENABLE command can be issued multiple times in a session. It is 1553 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1554 single command "ENABLE a b c". When multiple ENABLE commands are 1555 issued, each corresponding ENABLED response SHOULD only contain 1556 extensions enabled by the corresponding ENABLE command, i.e. for the 1557 above example, the ENABLED response to "ENABLE c" should not contain 1558 "a" or "b". 1560 There are no limitations on pipelining ENABLE. For example, it is 1561 possible to send ENABLE and then immediately SELECT, or a LOGIN 1562 immediately followed by ENABLE. 1564 The server MUST NOT change the CAPABILITY list as a result of 1565 executing ENABLE; i.e., a CAPABILITY command issued right after an 1566 ENABLE command MUST list the same capabilities as a CAPABILITY 1567 command issued before the ENABLE command. This is demonstrated in 1568 the following example: 1570 C: t1 CAPABILITY 1571 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1572 S: t1 OK foo 1573 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1574 S: * ENABLED X-GOOD-IDEA 1575 S: t2 OK foo 1576 C: t3 CAPABILITY 1577 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1578 S: t3 OK foo again 1580 In the following example, the client enables CONDSTORE: 1582 C: a1 ENABLE CONDSTORE 1583 S: * ENABLED CONDSTORE 1584 S: a1 OK Conditional Store enabled 1586 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1587 Command 1589 Designers of IMAP extensions are discouraged from creating extensions 1590 that require ENABLE unless there is no good alternative design. 1591 Specifically, extensions that cause potentially incompatible behavior 1592 changes to deployed server responses (and thus benefit from ENABLE) 1593 have a higher complexity cost than extensions that do not. 1595 6.3.2. SELECT Command 1597 Arguments: mailbox name 1599 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1600 REQUIRED OK untagged responses: PERMANENTFLAGS, 1601 UIDNEXT, UIDVALIDITY 1603 Result: OK - select completed, now in selected state 1604 NO - select failure, now in authenticated state: no 1605 such mailbox, can't access mailbox 1606 BAD - command unknown or arguments invalid 1608 The SELECT command selects a mailbox so that messages in the mailbox 1609 can be accessed. Before returning an OK to the client, the server 1610 MUST send the following untagged data to the client. Note that 1611 earlier versions of this protocol only required the FLAGS and EXISTS 1612 untagged data; consequently, client implementations SHOULD implement 1613 default behavior for missing data as discussed with the individual 1614 item. 1616 FLAGS Defined flags in the mailbox. See the description of the 1617 FLAGS response for more detail. 1619 EXISTS The number of messages in the mailbox. See the 1620 description of the EXISTS response for more detail. 1622 OK [PERMANENTFLAGS ()] A list of message flags that 1623 the client can change permanently. If this is missing, the client 1624 should assume that all flags can be changed permanently. 1626 OK [UIDNEXT ] The next unique identifier value. Refer to 1627 Section 2.3.1.1 for more information. If this is missing, the 1628 client can not make any assumptions about the next unique 1629 identifier value. 1631 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1632 Section 2.3.1.1 for more information. If this is missing, the 1633 server does not support unique identifiers. 1635 Only one mailbox can be selected at a time in a connection; 1636 simultaneous access to multiple mailboxes requires multiple 1637 connections. The SELECT command automatically deselects any 1638 currently selected mailbox before attempting the new selection. 1639 Consequently, if a mailbox is selected and a SELECT command that 1640 fails is attempted, no mailbox is selected. When deselecting a 1641 selected mailbox, the server MUST return an untagged OK response with 1642 the "[CLOSED]" response code when the currently selected mailbox is 1643 closed (see Paragraph 10). 1645 If the client is permitted to modify the mailbox, the server SHOULD 1646 prefix the text of the tagged OK response with the "[READ-WRITE]" 1647 response code. 1649 If the client is not permitted to modify the mailbox but is permitted 1650 read access, the mailbox is selected as read-only, and the server 1651 MUST prefix the text of the tagged OK response to SELECT with the 1652 "[READ-ONLY]" response code. Read-only access through SELECT differs 1653 from the EXAMINE command in that certain read-only mailboxes MAY 1654 permit the change of permanent state on a per-user (as opposed to 1655 global) basis. Netnews messages marked in a server-based .newsrc 1656 file are an example of such per-user permanent state that can be 1657 modified with read-only mailboxes. 1659 Example: C: A142 SELECT INBOX 1660 S: * 172 EXISTS 1661 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1662 S: * OK [UIDNEXT 4392] Predicted next UID 1663 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1664 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1665 S: A142 OK [READ-WRITE] SELECT completed 1667 Example: C: A142 SELECT INBOX 1668 S: * 172 EXISTS 1669 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1670 S: * OK [UIDNEXT 4392] Predicted next UID 1671 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1672 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1673 S: A142 OK [READ-WRITE] SELECT completed 1674 [...some time later...] 1675 C: A143 SELECT Drafts 1676 S: * OK [CLOSED] Previous mailbox is now closed 1677 S: * 5 EXISTS 1678 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1679 S: * OK [UIDNEXT 102] Predicted next UID 1680 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1681 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1682 \Flagged \Draft \*)] System flags and keywords allowed 1683 S: A143 OK [READ-WRITE] SELECT completed 1685 Note that IMAP4rev1 compliant servers can also send the untagged 1686 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1687 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1688 RECENT response. 1690 6.3.3. EXAMINE Command 1692 Arguments: mailbox name 1694 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1695 REQUIRED OK untagged responses: PERMANENTFLAGS, 1696 UIDNEXT, UIDVALIDITY 1698 Result: OK - examine completed, now in selected state 1699 NO - examine failure, now in authenticated state: no 1700 such mailbox, can't access mailbox BAD - command unknown 1701 or arguments invalid 1703 The EXAMINE command is identical to SELECT and returns the same 1704 output; however, the selected mailbox is identified as read-only. No 1705 changes to the permanent state of the mailbox, including per-user 1706 state, are permitted. 1708 The text of the tagged OK response to the EXAMINE command MUST begin 1709 with the "[READ-ONLY]" response code. 1711 Example: C: A932 EXAMINE blurdybloop 1712 S: * 17 EXISTS 1713 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1714 S: * OK [UIDNEXT 4392] Predicted next UID 1715 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1716 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1717 S: A932 OK [READ-ONLY] EXAMINE completed 1719 6.3.4. CREATE Command 1721 Arguments: mailbox name 1723 Responses: no specific responses for this command 1725 Result: OK - create completed 1726 NO - create failure: can't create mailbox with that name 1727 BAD - command unknown or arguments invalid 1729 The CREATE command creates a mailbox with the given name. An OK 1730 response is returned only if a new mailbox with that name has been 1731 created. It is an error to attempt to create INBOX or a mailbox with 1732 a name that refers to an extant mailbox. Any error in creation will 1733 return a tagged NO response. If a client attempts to create a UTF-8 1734 mailbox name that is not a valid Net-Unicode name, the server MUST 1735 reject the creation or convert the name to Net-Unicode prior to 1736 creating the mailbox. 1738 If the mailbox name is suffixed with the server's hierarchy separator 1739 character (as returned from the server by a LIST command), this is a 1740 declaration that the client intends to create mailbox names under 1741 this name in the hierarchy. Server implementations that do not 1742 require this declaration MUST ignore the declaration. In any case, 1743 the name created is without the trailing hierarchy delimiter. 1745 If the server's hierarchy separator character appears elsewhere in 1746 the name, the server SHOULD create any superior hierarchical names 1747 that are needed for the CREATE command to be successfully completed. 1748 In other words, an attempt to create "foo/bar/zap" on a server in 1749 which "/" is the hierarchy separator character SHOULD create foo/ and 1750 foo/bar/ if they do not already exist. 1752 If a new mailbox is created with the same name as a mailbox which was 1753 deleted, its unique identifiers MUST be greater than any unique 1754 identifiers used in the previous incarnation of the mailbox UNLESS 1755 the new incarnation has a different unique identifier validity value. 1756 See the description of the UID command for more detail. 1758 Example: C: A003 CREATE owatagusiam/ 1759 S: A003 OK CREATE completed 1760 C: A004 CREATE owatagusiam/blurdybloop 1761 S: A004 OK CREATE completed 1763 Note: The interpretation of this example depends on whether "/" 1764 was returned as the hierarchy separator from LIST. If "/" is the 1765 hierarchy separator, a new level of hierarchy named "owatagusiam" 1766 with a member called "blurdybloop" is created. Otherwise, two 1767 mailboxes at the same hierarchy level are created. 1769 6.3.5. DELETE Command 1771 Arguments: mailbox name 1773 Responses: no specific responses for this command 1775 Result: OK - delete completed 1776 NO - delete failure: can't delete mailbox with that name 1777 BAD - command unknown or arguments invalid 1779 The DELETE command permanently removes the mailbox with the given 1780 name. A tagged OK response is returned only if the mailbox has been 1781 deleted. It is an error to attempt to delete INBOX or a mailbox name 1782 that does not exist. 1784 The DELETE command MUST NOT remove inferior hierarchical names. For 1785 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1786 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1787 "foo.bar". It is an error to attempt to delete a name that has 1788 inferior hierarchical names and also has the \Noselect mailbox name 1789 attribute (see the description of the LIST response for more 1790 details). 1792 It is permitted to delete a name that has inferior hierarchical names 1793 and does not have the \Noselect mailbox name attribute. If the 1794 server implementation does not permit deleting the name while 1795 inferior hierarchical names exists then it SHOULD disallow the DELETE 1796 command by returning a tagged NO response. The NO response SHOULD 1797 include the HASCHILDREN response code. Alternatively the server MAY 1798 allow the DELETE command, but sets the \Noselect mailbox name 1799 attribute for that name. 1801 If the server returns OK response, all messages in that mailbox are 1802 removed by the DELETE command. 1804 The value of the highest-used unique identifier of the deleted 1805 mailbox MUST be preserved so that a new mailbox created with the same 1806 name will not reuse the identifiers of the former incarnation, UNLESS 1807 the new incarnation has a different unique identifier validity value. 1808 See the description of the UID command for more detail. 1810 Examples: C: A682 LIST "" * 1811 S: * LIST () "/" blurdybloop 1812 S: * LIST (\Noselect) "/" foo 1813 S: * LIST () "/" foo/bar 1814 S: A682 OK LIST completed 1815 C: A683 DELETE blurdybloop 1816 S: A683 OK DELETE completed 1817 C: A684 DELETE foo 1818 S: A684 NO Name "foo" has inferior hierarchical names 1819 C: A685 DELETE foo/bar 1820 S: A685 OK DELETE Completed 1821 C: A686 LIST "" * 1822 S: * LIST (\Noselect) "/" foo 1823 S: A686 OK LIST completed 1824 C: A687 DELETE foo 1825 S: A687 OK DELETE Completed 1826 C: A82 LIST "" * 1827 S: * LIST () "." blurdybloop 1828 S: * LIST () "." foo 1829 S: * LIST () "." foo.bar 1830 S: A82 OK LIST completed 1831 C: A83 DELETE blurdybloop 1832 S: A83 OK DELETE completed 1833 C: A84 DELETE foo 1834 S: A84 OK DELETE Completed 1835 C: A85 LIST "" * 1836 S: * LIST () "." foo.bar 1837 S: A85 OK LIST completed 1838 C: A86 LIST "" % 1839 S: * LIST (\Noselect) "." foo 1840 S: A86 OK LIST completed 1842 6.3.6. RENAME Command 1844 Arguments: existing mailbox name 1845 new mailbox name 1847 Responses: no specific responses for this command 1848 Result: OK - rename completed 1849 NO - rename failure: can't rename mailbox with that name, 1850 can't rename to mailbox with that name 1851 BAD - command unknown or arguments invalid 1853 The RENAME command changes the name of a mailbox. A tagged OK 1854 response is returned only if the mailbox has been renamed. It is an 1855 error to attempt to rename from a mailbox name that does not exist or 1856 to a mailbox name that already exists. Any error in renaming will 1857 return a tagged NO response. 1859 If the name has inferior hierarchical names, then the inferior 1860 hierarchical names MUST also be renamed. For example, a rename of 1861 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1862 delimiter character) to "zap/bar". 1864 If the server's hierarchy separator character appears in the name, 1865 the server SHOULD create any superior hierarchical names that are 1866 needed for the RENAME command to complete successfully. In other 1867 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1868 server in which "/" is the hierarchy separator character SHOULD 1869 create baz/ and baz/rag/ if they do not already exist. 1871 The value of the highest-used unique identifier of the old mailbox 1872 name MUST be preserved so that a new mailbox created with the same 1873 name will not reuse the identifiers of the former incarnation, UNLESS 1874 the new incarnation has a different unique identifier validity value. 1875 See the description of the UID command for more detail. 1877 Renaming INBOX is permitted, and has special behavior. (Note that 1878 some servers disallow renaming INBOX, so clients need to be able to 1879 handle such RENAME failing). It moves all messages in INBOX to a new 1880 mailbox with the given name, leaving INBOX empty. If the server 1881 implementation supports inferior hierarchical names of INBOX, these 1882 are unaffected by a rename of INBOX. 1884 Examples: C: A682 LIST "" * 1885 S: * LIST () "/" blurdybloop 1886 S: * LIST (\Noselect) "/" foo 1887 S: * LIST () "/" foo/bar 1888 S: A682 OK LIST completed 1889 C: A683 RENAME blurdybloop sarasoop 1890 S: A683 OK RENAME completed 1891 C: A684 RENAME foo zowie 1892 S: A684 OK RENAME Completed 1893 C: A685 LIST "" * 1894 S: * LIST () "/" sarasoop 1895 S: * LIST (\Noselect) "/" zowie 1896 S: * LIST () "/" zowie/bar 1897 S: A685 OK LIST completed 1899 C: Z432 LIST "" * 1900 S: * LIST () "." INBOX 1901 S: * LIST () "." INBOX.bar 1902 S: Z432 OK LIST completed 1903 C: Z433 RENAME INBOX old-mail 1904 S: Z433 OK RENAME completed 1905 C: Z434 LIST "" * 1906 S: * LIST () "." INBOX 1907 S: * LIST () "." INBOX.bar 1908 S: * LIST () "." old-mail 1909 S: Z434 OK LIST completed 1911 Note that renaming a mailbox doesn't update subscription information 1912 on the original name. To keep subscription information in sync, the 1913 following sequence of commands can be used: 1915 C: 1001 RENAME X Y 1916 C: 1002 SUBSCRIBE Y 1917 C: 1003 UNSUBSCRIBE X 1919 Note that the above sequence of commands doesn't account for updating 1920 subscription for any children mailboxes of mailbox X. 1922 6.3.7. SUBSCRIBE Command 1924 Arguments: mailbox 1926 Responses: no specific responses for this command 1928 Result: OK - subscribe completed 1929 NO - subscribe failure: can't subscribe to that name 1930 BAD - command unknown or arguments invalid 1932 The SUBSCRIBE command adds the specified mailbox name to the server's 1933 set of "active" or "subscribed" mailboxes as returned by the LIST 1934 (SUBSCRIBED) command. This command returns a tagged OK response if 1935 the subscription is successful or if the mailbox is already 1936 subscribed. 1938 A server MAY validate the mailbox argument to SUBSCRIBE to verify 1939 that it exists. However, it SHOULD NOT unilaterally remove an 1940 existing mailbox name from the subscription list even if a mailbox by 1941 that name no longer exists. 1943 Note: This requirement is because a server site can choose to 1944 routinely remove a mailbox with a well-known name (e.g., "system- 1945 alerts") after its contents expire, with the intention of 1946 recreating it when new contents are appropriate. 1948 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 1949 S: A002 OK SUBSCRIBE completed 1951 6.3.8. UNSUBSCRIBE Command 1953 Arguments: mailbox name 1955 Responses: no specific responses for this command 1957 Result: OK - unsubscribe completed 1958 NO - unsubscribe failure: can't unsubscribe that name 1959 BAD - command unknown or arguments invalid 1961 The UNSUBSCRIBE command removes the specified mailbox name from the 1962 server's set of "active" or "subscribed" mailboxes as returned by the 1963 LIST (SUBSCRIBED) command. This command returns a tagged OK response 1964 if the unsubscription is successful or if the mailbox is not 1965 subscribed. 1967 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 1968 S: A002 OK UNSUBSCRIBE completed 1970 6.3.9. LIST Command 1972 Arguments (basic): reference name 1973 mailbox name with possible wildcards 1975 Arguments (extended): selection options (OPTIONAL) 1976 reference name 1977 mailbox patterns 1978 return options (OPTIONAL) 1980 Responses: untagged responses: LIST 1982 Result: OK - list completed 1983 NO - list failure: can't list that reference or name 1984 BAD - command unknown or arguments invalid 1986 The LIST command returns a subset of names from the complete set of 1987 all names available to the client. Zero or more untagged LIST 1988 replies are returned, containing the name attributes, hierarchy 1989 delimiter, name, and possible extension information; see the 1990 description of the LIST reply for more detail. 1992 The LIST command SHOULD return its data quickly, without undue delay. 1993 For example, it SHOULD NOT go to excess trouble to calculate the 1994 \Marked or \Unmarked status or perform other processing; if each name 1995 requires 1 second of processing, then a list of 1200 names would take 1996 20 minutes! 1998 The extended LIST command, originally introduced in [RFC5258], 1999 provides capabilities beyond that of the original IMAP LIST command. 2000 The extended syntax is being used if one or more of the following 2001 conditions is true: 2003 1. if the first word after the command name begins with a 2004 parenthesis ("LIST selection options"); 2006 2. if the second word after the command name begins with a 2007 parenthesis; 2009 3. if the LIST command has more than 2 parameters ("LIST return 2010 options") 2012 An empty ("" string) reference name argument indicates that the 2013 mailbox name is interpreted as by SELECT. The returned mailbox names 2014 MUST match the supplied mailbox name pattern(s). A non-empty 2015 reference name argument is the name of a mailbox or a level of 2016 mailbox hierarchy, and indicates the context in which the mailbox 2017 name is interpreted. Clients SHOULD use the empty reference 2018 argument. 2020 In the basic syntax only, an empty ("" string) mailbox name argument 2021 is a special request to return the hierarchy delimiter and the root 2022 name of the name given in the reference. The value returned as the 2023 root MAY be the empty string if the reference is non-rooted or is an 2024 empty string. In all cases, a hierarchy delimiter (or NIL if there 2025 is no hierarchy) is returned. This permits a client to get the 2026 hierarchy delimiter (or find out that the mailbox names are flat) 2027 even when no mailboxes by that name currently exist. 2029 In the extended syntax, any mailbox name arguments that are empty 2030 strings are ignored. There is no special meaning for empty mailbox 2031 names when the extended syntax is used. 2033 The reference and mailbox name arguments are interpreted into a 2034 canonical form that represents an unambiguous left-to-right 2035 hierarchy. The returned mailbox names will be in the interpreted 2036 form, that we call "canonical LIST pattern" later in this document. 2037 To define the term "canonical LIST pattern" formally: it refers to 2038 the canonical pattern constructed internally by the server from the 2039 reference and mailbox name arguments. 2041 Note: The interpretation of the reference argument is 2042 implementation-defined. It depends upon whether the server 2043 implementation has a concept of the "current working directory" 2044 and leading "break out characters", which override the current 2045 working directory. 2047 For example, on a server which exports a UNIX or NT filesystem, 2048 the reference argument contains the current working directory, and 2049 the mailbox name argument would contain the name as interpreted in 2050 the current working directory. 2052 If a server implementation has no concept of break out characters, 2053 the canonical form is normally the reference name appended with 2054 the mailbox name. Note that if the server implements the 2055 namespace convention (Section 5.1.2.1), "#" is a break out 2056 character and must be treated as such. 2058 If the reference argument is not a level of mailbox hierarchy 2059 (that is, it is a \NoInferiors name), and/or the reference 2060 argument does not end with the hierarchy delimiter, it is 2061 implementation-dependent how this is interpreted. For example, a 2062 reference of "foo/bar" and mailbox name of "rag/baz" could be 2063 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2064 baz". A client SHOULD NOT use such a reference argument except at 2065 the explicit request of the user. A hierarchical browser MUST NOT 2066 make any assumptions about server interpretation of the reference 2067 unless the reference is a level of mailbox hierarchy AND ends with 2068 the hierarchy delimiter. 2070 Any part of the reference argument that is included in the 2071 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2072 be in the same form as the reference name argument. This rule 2073 permits the client to determine if the returned mailbox name is in 2074 the context of the reference argument, or if something about the 2075 mailbox argument overrode the reference argument. Without this rule, 2076 the client would have to have knowledge of the server's naming 2077 semantics including what characters are "breakouts" that override a 2078 naming context. 2080 For example, here are some examples of how references 2081 and mailbox names might be interpreted on a UNIX-based 2082 server: 2084 Reference Mailbox Name Interpretation 2085 ------------ ------------ -------------- 2086 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2087 archive/ % archive/% 2088 #news. comp.mail.* #news.comp.mail.* 2089 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2090 archive/ ~fred/Mail/* ~fred/Mail/* 2092 The first three examples demonstrate interpretations in 2093 the context of the reference argument. Note that 2094 "~smith/Mail" SHOULD NOT be transformed into something 2095 like "/u2/users/smith/Mail", or it would be impossible 2096 for the client to determine that the interpretation was 2097 in the context of the reference. 2099 The character "*" is a wildcard, and matches zero or more characters 2100 at this position. The character "%" is similar to "*", but it does 2101 not match a hierarchy delimiter. If the "%" wildcard is the last 2102 character of a mailbox name argument, matching levels of hierarchy 2103 are also returned. If these levels of hierarchy are not also 2104 selectable mailboxes, they are returned with the \Noselect mailbox 2105 name attribute (see the description of the LIST response for more 2106 details). 2108 Any syntactically valid pattern that is not accepted by a server for 2109 any reason MUST be silently ignored. I.e. it results in no LIST 2110 responses and the LIST command still returns tagged OK response. 2112 Selection options tell the server to limit the mailbox names that are 2113 selected by the LIST operation. If selection options are used, the 2114 mailboxes returned are those that match both the list of canonical 2115 LIST patterns and the selection options. Unless a particular 2116 selection option provides special rules, the selection options are 2117 cumulative: a mailbox that matches the mailbox patterns is selected 2118 only if it also matches all of the selection options. (An example of 2119 a selection option with special rules is the RECURSIVEMATCH option.) 2121 Return options control what information is returned for each matched 2122 mailbox. Return options MUST NOT cause the server to report 2123 information about additional mailbox names other than those that 2124 match the canonical LIST patterns and selection options. If no 2125 return options are specified, the client is only expecting 2126 information about mailbox attributes. The server MAY return other 2127 information about the matched mailboxes, and clients MUST be able to 2128 handle that situation. 2130 Initial selection options and return options are defined in the 2131 following subsections, and new ones will also be defined in 2132 extensions. Initial options defined in this document MUST be 2133 supported. Each non-initial option will be enabled by a capability 2134 string (one capability may enable multiple options), and a client 2135 MUST NOT send an option for which the server has not advertised 2136 support. A server MUST respond to options it does not recognize with 2137 a BAD response. The client SHOULD NOT specify any option more than 2138 once; however, if the client does this, the server MUST act as if it 2139 received the option only once. The order in which options are 2140 specified by the client is not significant. 2142 In general, each selection option except RECURSIVEMATCH will have a 2143 corresponding return option. The REMOTE selection option is an 2144 anomaly in this regard, and does not have a corresponding return 2145 option. That is because it expands, rather than restricts, the set 2146 of mailboxes that are returned. Future extensions to this 2147 specification should keep parallelism in mind and define a pair of 2148 corresponding options. 2150 Server implementations are permitted to "hide" otherwise accessible 2151 mailboxes from the wildcard characters, by preventing certain 2152 characters or names from matching a wildcard in certain situations. 2153 For example, a UNIX-based server might restrict the interpretation of 2154 "*" so that an initial "/" character does not match. 2156 The special name INBOX is included in the output from LIST, if INBOX 2157 is supported by this server for this user and if the uppercase string 2158 "INBOX" matches the interpreted reference and mailbox name arguments 2159 with wildcards as described above. The criteria for omitting INBOX 2160 is whether SELECT INBOX will return failure; it is not relevant 2161 whether the user's real INBOX resides on this or some other server. 2163 6.3.9.1. LIST Selection Options 2165 The selection options defined in this specification are as follows: 2167 SUBSCRIBED - causes the LIST command to list subscribed names, 2168 rather than the existing mailboxes. This will often be a subset 2169 of the actual mailboxes. It's also possible for this list to 2170 contain the names of mailboxes that don't exist. In any case, the 2171 list MUST include exactly those mailbox names that match the 2172 canonical list pattern and are subscribed to. 2174 This option defines a mailbox attribute, "\Subscribed", that 2175 indicates that a mailbox name is subscribed to. The "\Subscribed" 2176 attribute MUST be supported and MUST be accurately computed when 2177 the SUBSCRIBED selection option is specified. 2179 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2180 return option (see below). 2182 REMOTE - causes the LIST command to show remote mailboxes as well as 2183 local ones, as described in [RFC2193]. This option is intended to 2184 replace the RLIST command and, in conjunction with the SUBSCRIBED 2185 selection option, the RLSUB command. Servers that don't support 2186 remote mailboxes just ignore this option. 2188 This option defines a mailbox attribute, "\Remote", that indicates 2189 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2190 be accurately computed when the REMOTE option is specified. 2192 The REMOTE selection option has no interaction with other options. 2193 Its effect is to tell the server to apply the other options, if 2194 any, to remote mailboxes, in addition to local ones. In 2195 particular, it has no interaction with RECURSIVEMATCH (see below). 2196 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2197 request for (RECURSIVEMATCH) is also invalid. A request for 2198 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2199 mailboxes, both local and remote. 2201 RECURSIVEMATCH - this option forces the server to return information 2202 about parent mailboxes that don't match other selection options, 2203 but have some submailboxes that do. Information about children is 2204 returned in the CHILDINFO extended data item, as described in 2205 Section 6.3.9.6. 2207 Note 1: In order for a parent mailbox to be returned, it still has 2208 to match the canonical LIST pattern. 2210 Note 2: When returning the CHILDINFO extended data item, it 2211 doesn't matter whether or not the submailbox matches the canonical 2212 LIST pattern. See also example 9 in Section 6.3.9.7. 2214 The RECURSIVEMATCH option MUST NOT occur as the only selection 2215 option (or only with REMOTE), as it only makes sense when other 2216 selection options are also used. The server MUST return BAD 2217 tagged response in such case. 2219 Note that even if the RECURSIVEMATCH option is specified, the 2220 client MUST still be able to handle a case when a CHILDINFO 2221 extended data item is returned and there are no submailboxes that 2222 meet the selection criteria of the subsequent LIST command, as 2223 they can be deleted/renamed after the LIST response was sent, but 2224 before the client had a chance to access them. 2226 6.3.9.2. LIST Return Options 2228 The return options defined in this specification are as follows: 2230 SUBSCRIBED - causes the LIST command to return subscription state 2231 for all matching mailbox names. The "\Subscribed" attribute MUST 2232 be supported and MUST be accurately computed when the SUBSCRIBED 2233 return option is specified. Further, all mailbox flags MUST be 2234 accurately computed (this differs from the behavior of the 2235 obsolete LSUB command from IMAP4rev1). 2237 CHILDREN - requests mailbox child information as originally proposed 2238 in [RFC3348]. See Section 6.3.9.5, below, for details. This 2239 option MUST be supported by all servers. 2241 STATUS - requests STATUS response for each matching mailbox. 2243 This option takes STATUS data items as parameters. For each 2244 selectable mailbox matching the list pattern and selection 2245 options, the server MUST return an untagged LIST response 2246 followed by an untagged STATUS response containing the 2247 information requested in the STATUS return option. 2249 If an attempted STATUS for a listed mailbox fails because the 2250 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2251 is granted to the mailbox and the "r" right is not granted, or 2252 due to a race condition between LIST and STATUS changing the 2253 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2254 and the LIST response MUST include the \NoSelect attribute. 2255 This means the server may have to buffer the LIST reply until 2256 it has successfully looked up the necessary STATUS information. 2258 If the server runs into unexpected problems while trying to 2259 look up the STATUS information, it MAY drop the corresponding 2260 STATUS reply. In such a situation, the LIST command would 2261 still return a tagged OK reply. 2263 6.3.9.3. General Principles for Returning LIST Responses 2265 This section outlines several principles that can be used by server 2266 implementations of this document to decide whether a LIST response 2267 should be returned, as well as how many responses and what kind of 2268 information they may contain. 2270 1. At most one LIST response should be returned for each mailbox 2271 name that matches the canonical LIST pattern. Server 2272 implementors must not assume that clients will be able to 2273 assemble mailbox attributes and other information returned in 2274 multiple LIST responses. 2276 2. There are only two reasons for including a matching mailbox name 2277 in the responses to the LIST command (note that the server is 2278 allowed to return unsolicited responses at any time, and such 2279 responses are not governed by this rule): 2281 A. The mailbox name also satisfies the selection criteria. 2283 B. The mailbox name doesn't satisfy the selection criteria, but 2284 it has at least one descendant mailbox name that satisfies 2285 the selection criteria and that doesn't match the canonical 2286 LIST pattern. 2288 For more information on this case, see the CHILDINFO extended 2289 data item described in Section 6.3.9.6. Note that the 2290 CHILDINFO extended data item can only be returned when the 2291 RECURSIVEMATCH selection option is specified. 2293 3. Attributes returned in the same LIST response must be treated 2294 additively. For example, the following response 2296 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2298 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2299 subscribed. 2301 6.3.9.4. Additional LIST-related Requirements on Clients 2303 All clients MUST treat a LIST attribute with a stronger meaning as 2304 implying any attribute that can be inferred from it. (See 2305 Section 7.2.3 for the list of currently defined attributes). For 2306 example, the client must treat the presence of the \NoInferiors 2307 attribute as if the \HasNoChildren attribute was also sent by the 2308 server. 2310 The following table summarizes inference rules. 2312 +--------------------+-------------------+ 2313 | returned attribute | implied attribute | 2314 +--------------------+-------------------+ 2315 | \NoInferiors | \HasNoChildren | 2316 | \NonExistent | \NoSelect | 2317 +--------------------+-------------------+ 2319 6.3.9.5. The CHILDREN Return Option 2321 The CHILDREN return option implements the Child Mailbox Extension, 2322 originally proposed by Mike Gahrns and Raymond Cheng, of Microsoft 2323 Corporation. Most of the information in this section is taken 2324 directly from their original specification [RFC3348]. The CHILDREN 2325 return option is simply an indication that the client wants this 2326 information; a server MAY provide it even if the option is not 2327 specified. 2329 Many IMAP4 clients present to the user a hierarchical view of the 2330 mailboxes that a user has access to. Rather than initially 2331 presenting to the user the entire mailbox hierarchy, it is often 2332 preferable to show to the user a collapsed outline list of the 2333 mailbox hierarchy (particularly if there is a large number of 2334 mailboxes). The user can then expand the collapsed outline hierarchy 2335 as needed. It is common to include within the collapsed hierarchy a 2336 visual clue (such as a ''+'') to indicate that there are child 2337 mailboxes under a particular mailbox. When the visual clue is 2338 clicked, the hierarchy list is expanded to show the child mailboxes. 2339 The CHILDREN return option provides a mechanism for a client to 2340 efficiently determine whether a particular mailbox has children, 2341 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2342 The CHILDREN return option defines two new attributes that MUST be 2343 returned within a LIST response: \HasChildren and \HasNoChildren. 2344 Although these attributes MAY be returned in response to any LIST 2345 command, the CHILDREN return option is provided to indicate that the 2346 client particularly wants this information. If the CHILDREN return 2347 option is present, the server MUST return these attributes even if 2348 their computation is expensive. 2350 \HasChildren 2352 The presence of this attribute indicates that the mailbox has 2353 child mailboxes. A server SHOULD NOT set this attribute if 2354 there are child mailboxes and the user does not have permission 2355 to access any of them. In this case, \HasNoChildren SHOULD be 2356 used. In many cases, however, a server may not be able to 2357 efficiently compute whether a user has access to any child 2358 mailbox. Note that even though the \HasChildren attribute for a 2359 mailbox must be correct at the time of processing of the 2360 mailbox, a client must be prepared to deal with a situation when 2361 a mailbox is marked with the \HasChildren attribute, but no 2362 child mailbox appears in the response to the LIST command. This 2363 might happen, for example, due to children mailboxes being 2364 deleted or made inaccessible to the user (using access control) 2365 by another client before the server is able to list them. 2367 \HasNoChildren 2369 The presence of this attribute indicates that the mailbox has NO 2370 child mailboxes that are accessible to the currently 2371 authenticated user. 2373 It is an error for the server to return both a \HasChildren and a 2374 \HasNoChildren attribute in the same LIST response. 2376 Note: the \HasNoChildren attribute should not be confused with the 2377 the \NoInferiors attribute, which indicates that no child mailboxes 2378 exist now and none can be created in the future. 2380 6.3.9.6. CHILDINFO Extended Data Item 2382 The CHILDINFO extended data item MUST NOT be returned unless the 2383 client has specified the RECURSIVEMATCH selection option. 2385 The CHILDINFO extended data item in a LIST response describes the 2386 selection criteria that has caused it to be returned and indicates 2387 that the mailbox has at least one descendant mailbox that matches the 2388 selection criteria. 2390 Note: Some servers allow for mailboxes to exist without requiring 2391 their parent to exist. For example, a mailbox "Customers/ABC" can 2392 exist while the mailbox "Customers" does not. As CHILDINFO extended 2393 data item is not allowed if the RECURSIVEMATCH selection option is 2394 not specified, such servers SHOULD use the "\NonExistent 2395 \HasChildren" attribute pair to signal to the client that there is a 2396 descendant mailbox that matches the selection criteria. See example 2397 11 in Section 6.3.9.7. 2399 The returned selection criteria allow the client to distinguish a 2400 solicited response from an unsolicited one, as well as to distinguish 2401 among solicited responses caused by multiple pipelined LIST commands 2402 that specify different criteria. 2404 Servers SHOULD ONLY return a non-matching mailbox name along with 2405 CHILDINFO if at least one matching child is not also being returned. 2406 That is, servers SHOULD suppress redundant CHILDINFO responses. 2408 Examples 8 and 10 in Section 6.3.9.7 demonstrate the difference 2409 between present CHILDINFO extended data item and the "\HasChildren" 2410 attribute. 2412 The following table summarizes interaction between the "\NonExistent" 2413 attribute and CHILDINFO (the first column indicates whether the 2414 parent mailbox exists): 2416 +--------+--------------+--------------------+----------------------+ 2417 | exists | meets the | has a child that | returned LIST- | 2418 | | selection | meets the | EXTENDED attributes | 2419 | | criteria | selection criteria | and CHILDINFO | 2420 +--------+--------------+--------------------+----------------------+ 2421 | no | no | no | no LIST response | 2422 | | | | returned | 2423 | yes | no | no | no LIST response | 2424 | | | | returned | 2425 | no | yes | no | (\NonExistent | 2426 | | | | ) | 2427 | yes | yes | no | () | 2428 | no | no | yes | (\NonExistent) + | 2429 | | | | CHILDINFO | 2430 | yes | no | yes | () + CHILDINFO | 2431 | no | yes | yes | (\NonExistent | 2432 | | | | ) + CHILDINFO | 2433 | yes | yes | yes | () + CHILDINFO | 2434 +--------+--------------+--------------------+----------------------+ 2436 where is one or more attributes that correspond to the 2437 selection criteria; for example, for the SUBSCRIBED option the 2438 is \Subscribed. 2440 6.3.9.7. LIST Command Examples 2442 This example shows some uses of the basic LIST command: 2444 Example: C: A101 LIST "" "" 2445 S: * LIST (\Noselect) "/" "" 2446 S: A101 OK LIST Completed 2447 C: A102 LIST #news.comp.mail.misc "" 2448 S: * LIST (\Noselect) "." #news. 2449 S: A102 OK LIST Completed 2450 C: A103 LIST /usr/staff/jones "" 2451 S: * LIST (\Noselect) "/" / 2452 S: A103 OK LIST Completed 2453 C: A202 LIST ~/Mail/ % 2454 S: * LIST (\Noselect) "/" ~/Mail/foo 2455 S: * LIST () "/" ~/Mail/meetings 2456 S: A202 OK LIST completed 2458 Extended examples: 2460 1: The first example shows the complete local hierarchy that will 2461 be used for the other examples. 2463 C: A01 LIST "" "*" 2464 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2465 S: * LIST () "/" "Fruit" 2466 S: * LIST () "/" "Fruit/Apple" 2467 S: * LIST () "/" "Fruit/Banana" 2468 S: * LIST () "/" "Tofu" 2469 S: * LIST () "/" "Vegetable" 2470 S: * LIST () "/" "Vegetable/Broccoli" 2471 S: * LIST () "/" "Vegetable/Corn" 2472 S: A01 OK done 2474 2: In the next example, we will see the subscribed mailboxes. This 2475 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2477 that the mailbox called "Fruit/Peach" is subscribed to, but does 2478 not actually exist (perhaps it was deleted while still 2479 subscribed). The "Fruit" mailbox is not subscribed to, but it 2480 has two subscribed children. The "Vegetable" mailbox is 2481 subscribed and has two children; one of them is subscribed as 2482 well. 2484 C: A02 LIST (SUBSCRIBED) "" "*" 2485 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2486 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2487 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2488 S: * LIST (\Subscribed) "/" "Vegetable" 2489 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2490 S: A02 OK done 2492 3: The next example shows the use of the CHILDREN option. The 2493 client, without having to list the second level of hierarchy, 2494 now knows which of the top-level mailboxes have submailboxes 2495 (children) and which do not. Note that it's not necessary for 2496 the server to return the \HasNoChildren attribute for the inbox, 2497 because the \NoInferiors attribute already implies that, and has 2498 a stronger meaning. 2500 C: A03 LIST () "" "%" RETURN (CHILDREN) 2501 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2502 S: * LIST (\HasChildren) "/" "Fruit" 2503 S: * LIST (\HasNoChildren) "/" "Tofu" 2504 S: * LIST (\HasChildren) "/" "Vegetable" 2505 S: A03 OK done 2507 4: In this example, we see more mailboxes that reside on another 2508 server. This is similar to the command . 2510 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2511 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2512 S: * LIST (\HasChildren) "/" "Fruit" 2513 S: * LIST (\HasNoChildren) "/" "Tofu" 2514 S: * LIST (\HasChildren) "/" "Vegetable" 2515 S: * LIST (\Remote) "/" "Bread" 2516 S: * LIST (\HasChildren \Remote) "/" "Meat" 2517 S: A04 OK done 2519 5: The following example also requests the server to include 2520 mailboxes that reside on another server. The server returns 2521 information about all mailboxes that are subscribed. This is 2522 similar to the command (see [RFC2193] for more 2523 details on RLSUB). We also see the use of two selection 2524 options. 2526 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2527 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2528 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2529 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2530 S: * LIST (\Subscribed) "/" "Vegetable" 2531 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2532 S: * LIST (\Remote \Subscribed) "/" "Bread" 2533 S: A05 OK done 2535 6: The following example requests the server to include mailboxes 2536 that reside on another server. The server is asked to return 2537 subscription information for all returned mailboxes. This is 2538 different from the example above. 2540 Note that the output of this command is not a superset of the 2541 output in the previous example, as it doesn't include LIST 2542 response for the non-existent "Fruit/Peach". 2544 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2545 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2546 S: * LIST () "/" "Fruit" 2547 S: * LIST () "/" "Fruit/Apple" 2548 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2549 S: * LIST () "/" "Tofu" 2550 S: * LIST (\Subscribed) "/" "Vegetable" 2551 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2552 S: * LIST () "/" "Vegetable/Corn" 2553 S: * LIST (\Remote \Subscribed) "/" "Bread" 2554 S: * LIST (\Remote) "/" "Meat" 2555 S: A06 OK done 2557 7: The following example demonstrates the difference between the 2558 \HasChildren attribute and the CHILDINFO extended data item. 2560 Let's assume there is the following hierarchy: 2562 C: C01 LIST "" "*" 2563 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2564 S: * LIST () "/" "Foo" 2565 S: * LIST () "/" "Foo/Bar" 2566 S: * LIST () "/" "Foo/Baz" 2567 S: * LIST () "/" "Moo" 2568 S: C01 OK done 2570 If the client asks RETURN (CHILDREN), it will get this: 2572 C: CA3 LIST "" "%" RETURN (CHILDREN) 2573 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2574 S: * LIST (\HasChildren) "/" "Foo" 2575 S: * LIST (\HasNoChildren) "/" "Moo" 2576 S: CA3 OK done 2578 A) Let's also assume that the mailbox "Foo/Baz" is the only 2579 subscribed mailbox. Then we get this result: 2581 C: C02 LIST (SUBSCRIBED) "" "*" 2582 S: * LIST (\Subscribed) "/" "Foo/Baz" 2583 S: C02 OK done 2585 Now, if the client issues , the server 2586 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2587 "Inbox" are NOT subscribed). However, if the client issues 2588 this: 2590 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2591 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2592 S: C04 OK done 2594 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2595 that is.) 2597 A1) If the mailbox "Foo" had also been subscribed, the last 2598 command would return this: 2600 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2601 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2602 S: C04 OK done 2604 or even this: 2606 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2607 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2608 ("SUBSCRIBED")) 2609 S: C04 OK done 2611 A2) If we assume instead that the mailbox "Foo" is not part of 2612 the original hierarchy and is not subscribed, the last command 2613 will give this result: 2615 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2616 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2617 S: C04 OK done 2619 B) Now, let's assume that no mailbox is subscribed. In this 2620 case, the command will 2621 return no responses, as there are no subscribed children (even 2622 though "Foo" has children). 2624 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2625 are subscribed. In that case, we see this result: 2627 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2628 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2629 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2630 S: C04 OK done 2632 (which means that the mailbox "Foo" has children, but none of 2633 them is subscribed). 2635 8: The following example demonstrates that the CHILDINFO extended 2636 data item is returned whether or not children mailboxes match 2637 the canonical LIST pattern. 2639 Let's assume there is the following hierarchy: 2641 C: D01 LIST "" "*" 2642 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2643 S: * LIST () "/" "foo2" 2644 S: * LIST () "/" "foo2/bar1" 2645 S: * LIST () "/" "foo2/bar2" 2646 S: * LIST () "/" "baz2" 2647 S: * LIST () "/" "baz2/bar2" 2648 S: * LIST () "/" "baz2/bar22" 2649 S: * LIST () "/" "baz2/bar222" 2650 S: * LIST () "/" "eps2" 2651 S: * LIST () "/" "eps2/mamba" 2652 S: * LIST () "/" "qux2/bar2" 2653 S: D01 OK done 2655 And that the following mailboxes are subscribed: 2657 C: D02 LIST (SUBSCRIBED) "" "*" 2658 S: * LIST (\Subscribed) "/" "foo2/bar1" 2659 S: * LIST (\Subscribed) "/" "foo2/bar2" 2660 S: * LIST (\Subscribed) "/" "baz2/bar2" 2661 S: * LIST (\Subscribed) "/" "baz2/bar22" 2662 S: * LIST (\Subscribed) "/" "baz2/bar222" 2663 S: * LIST (\Subscribed) "/" "eps2" 2664 S: * LIST (\Subscribed) "/" "eps2/mamba" 2665 S: * LIST (\Subscribed) "/" "qux2/bar2" 2666 S: D02 OK done 2668 The client issues the following command first: 2670 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2671 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2672 S: * LIST (\Subscribed) "/" "foo2/bar2" 2673 S: * LIST (\Subscribed) "/" "baz2/bar2" 2674 S: * LIST (\Subscribed) "/" "baz2/bar22" 2675 S: * LIST (\Subscribed) "/" "baz2/bar222" 2676 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2677 S: * LIST (\Subscribed) "/" "qux2/bar2" 2678 S: D03 OK done 2680 and the server may also include (but this would violate a SHOULD 2681 NOT in Section 3.5, because CHILDINFO is redundant) 2683 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2684 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2685 The CHILDINFO extended data item is returned for mailboxes 2686 "foo2", "baz2", and "eps2", because all of them have subscribed 2687 children, even though for the mailbox "foo2" only one of the two 2688 subscribed children matches the pattern, for the mailbox "baz2" 2689 all the subscribed children match the pattern, and for the 2690 mailbox "eps2" none of the subscribed children matches the 2691 pattern. 2693 Note that if the client issues 2695 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2696 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2697 S: * LIST (\Subscribed) "/" "foo2/bar1" 2698 S: * LIST (\Subscribed) "/" "foo2/bar2" 2699 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2700 S: * LIST (\Subscribed) "/" "baz2/bar2" 2701 S: * LIST (\Subscribed) "/" "baz2/bar22" 2702 S: * LIST (\Subscribed) "/" "baz2/bar222" 2703 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2704 S: * LIST (\Subscribed) "/" "eps2/mamba" 2705 S: * LIST (\Subscribed) "/" "qux2/bar2" 2706 S: D03 OK done 2708 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2709 still have the CHILDINFO extended data item, even though this 2710 information is redundant and the client can determine it by 2711 itself. 2713 9: The following example shows usage of extended syntax for mailbox 2714 pattern. It also demonstrates that the presence of the 2715 CHILDINFO extended data item doesn't necessarily imply 2716 \HasChildren. 2718 C: a1 LIST "" ("foo") 2719 S: * LIST () "/" foo 2720 S: a1 OK done 2722 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2723 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2724 S: a2 OK done 2726 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2727 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2728 S: a3 OK done 2730 10: The following example shows how a server that supports missing 2731 mailbox hierarchy elements can signal to a client that didn't 2732 specify the RECURSIVEMATCH selection option that there is a 2733 child mailbox that matches the selection criteria. 2735 C: a1 LIST (REMOTE) "" * 2736 S: * LIST () "/" music/rock 2737 S: * LIST (\Remote) "/" also/jazz 2738 S: a1 OK done 2740 C: a2 LIST () "" % 2741 S: * LIST (\NonExistent \HasChildren) "/" music 2742 S: a2 OK done 2744 C: a3 LIST (REMOTE) "" % 2745 S: * LIST (\NonExistent \HasChildren) "/" music 2746 S: * LIST (\NonExistent \HasChildren) "/" also 2747 S: a3 OK done 2749 C: a3.1 LIST "" (% music/rock) 2750 S: * LIST () "/" music/rock 2751 S: a3.1 OK done 2753 Because "music/rock" is the only mailbox under "music", there's 2754 no need for the server to also return "music". However clients 2755 must handle both cases. 2757 11: The following examples show use of STATUS return option. 2759 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2760 S: * LIST () "." "INBOX" 2761 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2762 S: * LIST () "." "foo" 2763 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2764 S: * LIST (\NoSelect) "." "bar" 2765 S: A01 OK List completed. 2767 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2769 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2770 (MESSAGES)) 2771 S: * LIST (\Subscribed) "." "INBOX" 2772 S: * STATUS "INBOX" (MESSAGES 17) 2773 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2774 S: A02 OK List completed. 2776 The LIST reply for "foo" is returned because it has matching 2777 children, but no STATUS reply is returned because "foo" itself 2778 doesn't match the selection criteria. 2780 6.3.10. NAMESPACE Command 2782 Arguments: none 2784 Responses: REQUIRED untagged responses: NAMESPACE 2786 Result: OK - command completed 2787 NO - Can't complete the command 2788 BAD - arguments invalid 2790 The NAMESPACE command causes a single ungagged NAMESPACE response to 2791 be returned. The untagged NAMESPACE response contains the prefix and 2792 hierarchy delimiter to the server's Personal Namespace(s), Other 2793 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2794 to expose. The response will contain a NIL for any namespace class 2795 that is not available. Namespace-Response-Extensions ABNF non 2796 terminal is defined for extensibility and MAY be included in the 2797 response. 2799 Example 1: 2801 In this example a server supports a single personal namespace. No 2802 leading prefix is used on personal mailboxes and "/" is the hierarchy 2803 delimiter. 2805 C: A001 NAMESPACE 2806 S: * NAMESPACE (("" "/")) NIL NIL 2807 S: A001 OK NAMESPACE command completed 2809 Example 2: 2811 A user logged on anonymously to a server. No personal mailboxes are 2812 associated with the anonymous user and the user does not have access 2813 to the Other Users' Namespace. No prefix is required to access 2814 shared mailboxes and the hierarchy delimiter is "." 2816 C: A001 NAMESPACE 2817 S: * NAMESPACE NIL NIL (("" ".")) 2818 S: A001 OK NAMESPACE command completed 2820 Example 3: 2822 A server that contains a Personal Namespace and a single Shared 2823 Namespace. 2825 C: A001 NAMESPACE 2826 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2827 S: A001 OK NAMESPACE command completed 2829 Example 4: 2831 A server that contains a Personal Namespace, Other Users' Namespace 2832 and multiple Shared Namespaces. Note that the hierarchy delimiter 2833 used within each namespace can be different. 2835 C: A001 NAMESPACE 2836 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2837 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2838 S: A001 OK NAMESPACE command completed 2840 The prefix string allows a client to do things such as automatically 2841 creating personal mailboxes or LISTing all available mailboxes within 2842 a namespace. 2844 Example 5: 2846 A server that supports only the Personal Namespace, with a leading 2847 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2848 "." 2850 C: A001 NAMESPACE 2851 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2852 S: A001 OK NAMESPACE command completed 2854 < Automatically create a mailbox to store sent items.> 2856 C: A002 CREATE "INBOX.Sent Mail" 2857 S: A002 OK CREATE command completed 2859 Although typically a server will support only a single Personal 2860 Namespace, and a single Other User's Namespace, circumstances exist 2861 where there MAY be multiples of these, and a client MUST be prepared 2862 for them. If a client is configured such that it is required to 2863 create a certain mailbox, there can be circumstances where it is 2864 unclear which Personal Namespaces it should create the mailbox in. 2865 In these situations a client SHOULD let the user select which 2866 namespaces to create the mailbox in or just use the first personal 2867 namespace. 2869 Example 6: 2871 In this example, a server supports 2 Personal Namespaces. In 2872 addition to the regular Personal Namespace, the user has an 2873 additional personal namespace to allow access to mailboxes in an MH 2874 format mailstore. 2876 The client is configured to save a copy of all mail sent by the user 2877 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2878 deleted from a mailbox, the client is configured to move that message 2879 to a mailbox called 'Deleted Items'. 2881 Note that this example demonstrates how some extension flags can be 2882 passed to further describe the #mh namespace. 2884 C: A001 NAMESPACE 2885 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2886 ("FLAG1" "FLAG2"))) NIL NIL 2887 S: A001 OK NAMESPACE command completed 2889 < It is desired to keep only one copy of sent mail. 2890 It is unclear which Personal Namespace the client 2891 should use to create the 'Sent Mail' mailbox. 2892 The user is prompted to select a namespace and only 2893 one 'Sent Mail' mailbox is created. > 2895 C: A002 CREATE "Sent Mail" 2896 S: A002 OK CREATE command completed 2898 < The client is designed so that it keeps two 2899 'Deleted Items' mailboxes, one for each namespace. > 2901 C: A003 CREATE "Delete Items" 2902 S: A003 OK CREATE command completed 2904 C: A004 CREATE "#mh/Deleted Items" 2905 S: A004 OK CREATE command completed 2907 The next level of hierarchy following the Other Users' Namespace 2908 prefix SHOULD consist of , where is a user name 2909 as per the LOGIN or AUTHENTICATE command. 2911 A client can construct a LIST command by appending a "%" to the Other 2912 Users' Namespace prefix to discover the Personal Namespaces of other 2913 users that are available to the currently authenticated user. 2915 In response to such a LIST command, a server SHOULD NOT return user 2916 names that have not granted access to their personal mailboxes to the 2917 user in question. 2919 A server MAY return a LIST response containing only the names of 2920 users that have explicitly granted access to the user in question. 2922 Alternatively, a server MAY return NO to such a LIST command, 2923 requiring that a user name be included with the Other Users' 2924 Namespace prefix before listing any other user's mailboxes. 2926 Example 7: 2928 A server that supports providing a list of other user's mailboxes 2929 that are accessible to the currently logged on user. 2931 C: A001 NAMESPACE 2932 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 2933 S: A001 OK NAMESPACE command completed 2935 C: A002 LIST "" "Other Users/%" 2936 S: * LIST () "/" "Other Users/Mike" 2937 S: * LIST () "/" "Other Users/Karen" 2938 S: * LIST () "/" "Other Users/Matthew" 2939 S: * LIST () "/" "Other Users/Tesa" 2940 S: A002 OK LIST command completed 2942 Example 8: 2944 A server that does not support providing a list of other user's 2945 mailboxes that are accessible to the currently logged on user. The 2946 mailboxes are listable if the client includes the name of the other 2947 user with the Other Users' Namespace prefix. 2949 C: A001 NAMESPACE 2950 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 2951 S: A001 OK NAMESPACE command completed 2953 < In this example, the currently logged on user has access to 2954 the Personal Namespace of user Mike, but the server chose to 2955 suppress this information in the LIST response. However, 2956 by appending the user name Mike (received through user input) 2957 to the Other Users' Namespace prefix, the client is able 2958 to get a listing of the personal mailboxes of user Mike. > 2960 C: A002 LIST "" "#Users/%" 2961 S: A002 NO The requested item could not be found. 2963 C: A003 LIST "" "#Users/Mike/%" 2964 S: * LIST () "/" "#Users/Mike/INBOX" 2965 S: * LIST () "/" "#Users/Mike/Foo" 2966 S: A003 OK LIST command completed. 2968 A prefix string might not contain a hierarchy delimiter, because in 2969 some cases it is not needed as part of the prefix. 2971 Example 9: 2973 A server that allows access to the Other Users' Namespace by 2974 prefixing the others' mailboxes with a '~' followed by , 2975 where is a user name as per the LOGIN or AUTHENTICATE 2976 command. 2978 C: A001 NAMESPACE 2979 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 2980 S: A001 OK NAMESPACE command completed 2982 < List the mailboxes for user mark > 2984 C: A002 LIST "" "~mark/%" 2985 S: * LIST () "/" "~mark/INBOX" 2986 S: * LIST () "/" "~mark/foo" 2987 S: A002 OK LIST command completed 2989 6.3.11. STATUS Command 2991 Arguments: mailbox name 2992 status data item names 2994 Responses: REQUIRED untagged responses: STATUS 2996 Result: OK - status completed 2997 NO - status failure: no status for that name 2998 BAD - command unknown or arguments invalid 3000 The STATUS command requests the status of the indicated mailbox. It 3001 does not change the currently selected mailbox, nor does it affect 3002 the state of any messages in the queried mailbox. 3004 The STATUS command provides an alternative to opening a second 3005 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3006 query that mailbox's status without deselecting the current mailbox 3007 in the first IMAP4rev2 connection. 3009 Unlike the LIST command, the STATUS command is not guaranteed to be 3010 fast in its response. Under certain circumstances, it can be quite 3011 slow. In some implementations, the server is obliged to open the 3012 mailbox read-only internally to obtain certain status information. 3013 Also unlike the LIST command, the STATUS command does not accept 3014 wildcards. 3016 Note: The STATUS command is intended to access the status of 3017 mailboxes other than the currently selected mailbox. Because the 3018 STATUS command can cause the mailbox to be opened internally, and 3019 because this information is available by other means on the 3020 selected mailbox, the STATUS command SHOULD NOT be used on the 3021 currently selected mailbox. However, servers MUST be able to 3022 execute STATUS command on the selected mailbox. (This might also 3023 implicitly happen when STATUS return option is used in a LIST 3024 command). 3026 The STATUS command MUST NOT be used as a "check for new messages 3027 in the selected mailbox" operation (refer to sections Section 7, 3028 Section 7.3.1 for more information about the proper method for new 3029 message checking). 3031 STATUS SIZE (see below) can take a significant amount of time, 3032 depending upon server implementation. Clients should use STATUS 3033 SIZE cautiously. 3035 The currently defined status data items that can be requested are: 3037 MESSAGES The number of messages in the mailbox. 3039 UIDNEXT The next unique identifier value of the mailbox. Refer to 3040 Section 2.3.1.1 for more information. 3042 UIDVALIDITY The unique identifier validity value of the mailbox. 3043 Refer to Section 2.3.1.1 for more information. 3045 UNSEEN The number of messages which do not have the \Seen flag set. 3047 DELETED The number of messages which have the \Deleted flag set. 3049 SIZE The total size of the mailbox in octets. This is not strictly 3050 required to be an exact value, but it MUST be equal to or greater 3051 than the sum of the values of the RFC822.SIZE FETCH message data 3052 items (see Section 6.4.5) of all messages in the mailbox. 3054 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3055 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3056 S: A042 OK STATUS completed 3058 6.3.12. APPEND Command 3060 Arguments: mailbox name 3061 OPTIONAL flag parenthesized list 3062 OPTIONAL date/time string 3063 message literal 3065 Responses: no specific responses for this command 3066 Result: OK - append completed 3067 NO - append error: can't append to that mailbox, error 3068 in flags or date/time or message text 3069 BAD - command unknown or arguments invalid 3071 The APPEND command appends the literal argument as a new message to 3072 the end of the specified destination mailbox. This argument SHOULD 3073 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3074 characters are permitted in the message. A server implementation 3075 that is unable to preserve 8-bit data properly MUST be able to 3076 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3077 content transfer encoding. 3079 Note: There may be exceptions, e.g., draft messages, in which 3080 required [RFC-5322] header lines are omitted in the message 3081 literal argument to APPEND. The full implications of doing so 3082 must be understood and carefully weighed. 3084 If a flag parenthesized list is specified, the flags SHOULD be set in 3085 the resulting message; otherwise, the flag list of the resulting 3086 message is set to empty by default. 3088 If a date-time is specified, the internal date SHOULD be set in the 3089 resulting message; otherwise, the internal date of the resulting 3090 message is set to the current date and time by default. 3092 If the append is unsuccessful for any reason, the mailbox MUST be 3093 restored to its state before the APPEND attempt (other than possibly 3094 keeping the changed mailbox's UIDNEXT value); no partial appending is 3095 permitted. 3097 If the destination mailbox does not exist, a server MUST return an 3098 error, and MUST NOT automatically create the mailbox. Unless it is 3099 certain that the destination mailbox can not be created, the server 3100 MUST send the response code "[TRYCREATE]" as the prefix of the text 3101 of the tagged NO response. This gives a hint to the client that it 3102 can attempt a CREATE command and retry the APPEND if the CREATE is 3103 successful. 3105 On successful completion of an APPEND, the server SHOULD return an 3106 APPENDUID response code. 3108 In the case of a mailbox that has permissions set so that the client 3109 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3110 SHOULD NOT send an APPENDUID response code as it would disclose 3111 information about the mailbox. 3113 In the case of a mailbox that has UIDNOTSTICKY status (see 3114 UIDNOTSTICKY response code definition), the server MAY omit the 3115 APPENDUID response code as it is not meaningful. 3117 If the server does not return the APPENDUID response codes, the 3118 client can discover this information by selecting the destination 3119 mailbox. The location of messages placed in the destination mailbox 3120 by APPEND can be determined by using FETCH and/or SEARCH commands 3121 (e.g., for Message-ID or some unique marker placed in the message in 3122 an APPEND). 3124 If the mailbox is currently selected, the normal new message actions 3125 SHOULD occur. Specifically, the server SHOULD notify the client 3126 immediately via an untagged EXISTS response. If the server does not 3127 do so, the client MAY issue a NOOP command after one or more APPEND 3128 commands. 3130 Example: C: A003 APPEND saved-messages (\Seen) {310} 3131 S: + Ready for literal data 3132 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3133 C: From: Fred Foobar 3134 C: Subject: afternoon meeting 3135 C: To: mooch@owatagu.siam.edu 3136 C: Message-Id: 3137 C: MIME-Version: 1.0 3138 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3139 C: 3140 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3141 C: 3142 S: A003 OK APPEND completed 3144 Example: C: A003 APPEND saved-messages (\Seen) {297} 3145 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3146 C: From: Fred Foobar 3147 C: Subject: afternoon meeting 3148 C: To: mooch@example.com 3149 C: Message-Id: 3150 C: MIME-Version: 1.0 3151 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3152 C: 3153 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3154 C: 3155 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3156 C: A004 COPY 2:4 meeting 3157 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3158 C: A005 UID COPY 305:310 meeting 3159 S: A005 OK No matching messages, so nothing copied 3160 C: A006 COPY 2 funny 3161 S: A006 OK Done 3162 C: A007 SELECT funny 3163 S: * 1 EXISTS 3164 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3165 S: * OK [UIDNEXT 2] Predicted next UID 3166 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3167 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3168 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3169 S: A007 OK [READ-WRITE] SELECT completed 3171 In this example, A003 and A004 demonstrate successful appending and 3172 copying to a mailbox that returns the UIDs assigned to the messages. 3173 A005 is an example in which no messages were copied; this is because 3174 in A003, we see that message 2 had UID 304, and message 3 had UID 3175 319; therefore, UIDs 305 through 310 do not exist (refer to 3176 Section 2.3.1.1 for further explanation). A006 is an example of a 3177 message being copied that did not return a COPYUID; and, as expected, 3178 A007 shows that the mail store containing that mailbox does not 3179 support persistent UIDs. 3181 Note: The APPEND command is not used for message delivery, because 3182 it does not provide a mechanism to transfer [SMTP] envelope 3183 information. 3185 6.3.13. IDLE Command 3187 Arguments: none 3189 Responses: continuation data will be requested; the client sends the 3190 continuation data "DONE" to end the command 3192 Result: OK - IDLE completed after client sent "DONE" 3193 NO - failure: the server will not allow the IDLE command 3194 at this time 3195 BAD - command unknown or arguments invalid 3197 Without the IDLE command a client requires to poll the server for 3198 changes to the selected mailbox (new mail, deletions, flag changes). 3199 It's often more desirable to have the server transmit updates to the 3200 client in real time. This allows a user to see new mail immediately. 3201 The IDLE command allows a client to tell the server that it's ready 3202 to accept such real-time updates. 3204 The IDLE command is sent from the client to the server when the 3205 client is ready to accept unsolicited update messages. The server 3206 requests a response to the IDLE command using the continuation ("+") 3207 response. The IDLE command remains active until the client responds 3208 to the continuation, and as long as an IDLE command is active, the 3209 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3210 responses at any time. If the server choose to send unsolicited 3211 FETCH responses, they MUST include UID FETCH item. 3213 The IDLE command is terminated by the receipt of a "DONE" 3214 continuation from the client; such response satisfies the server's 3215 continuation request. At that point, the server MAY send any 3216 remaining queued untagged responses and then MUST immediately send 3217 the tagged response to the IDLE command and prepare to process other 3218 commands. As for other commands, the processing of any new command 3219 may cause the sending of unsolicited untagged responses, subject to 3220 the ambiguity limitations. The client MUST NOT send a command while 3221 the server is waiting for the DONE, since the server will not be able 3222 to distinguish a command from a continuation. 3224 The server MAY consider a client inactive if it has an IDLE command 3225 running, and if such a server has an inactivity timeout it MAY log 3226 the client off implicitly at the end of its timeout period. Because 3227 of that, clients using IDLE are advised to terminate the IDLE and re- 3228 issue it at least every 29 minutes to avoid being logged off. This 3229 still allows a client to receive immediate mailbox updates even 3230 though it need only "poll" at half hour intervals. 3232 Example: C: A001 SELECT INBOX 3233 S: * FLAGS (\Deleted \Seen \Flagged) 3234 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3235 S: * 3 EXISTS 3236 S: * OK [UIDVALIDITY 1] 3237 S: A001 OK [READ-WRITE] SELECT completed 3238 C: A002 IDLE 3239 S: + idling 3240 ...time passes; new mail arrives... 3241 S: * 4 EXISTS 3242 C: DONE 3243 S: A002 OK IDLE terminated 3244 ...another client expunges message 2 now... 3245 C: A003 FETCH 4 ALL 3246 S: * 4 FETCH (...) 3247 S: A003 OK FETCH completed 3248 C: A004 IDLE 3249 S: * 2 EXPUNGE 3250 S: * 3 EXISTS 3251 S: + idling 3252 ...time passes; another client expunges message 3... 3253 S: * 3 EXPUNGE 3254 S: * 2 EXISTS 3255 ...time passes; new mail arrives... 3256 S: * 3 EXISTS 3257 C: DONE 3258 S: A004 OK IDLE terminated 3259 C: A005 FETCH 3 ALL 3260 S: * 3 FETCH (...) 3261 S: A005 OK FETCH completed 3262 C: A006 IDLE 3264 6.4. Client Commands - Selected State 3266 In the selected state, commands that manipulate messages in a mailbox 3267 are permitted. 3269 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3270 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3271 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3272 APPEND), the following commands are valid in the selected state: 3273 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3275 6.4.1. CLOSE Command 3277 Arguments: none 3279 Responses: no specific responses for this command 3280 Result: OK - close completed, now in authenticated state 3281 BAD - command unknown or arguments invalid 3283 The CLOSE command permanently removes all messages that have the 3284 \Deleted flag set from the currently selected mailbox, and returns to 3285 the authenticated state from the selected state. No untagged EXPUNGE 3286 responses are sent. 3288 No messages are removed, and no error is given, if the mailbox is 3289 selected by an EXAMINE command or is otherwise selected read-only. 3291 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3292 MAY be issued without previously issuing a CLOSE command. The 3293 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3294 selected mailbox without doing an expunge. However, when many 3295 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3296 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3297 no untagged EXPUNGE responses (which the client would probably 3298 ignore) are sent. 3300 Example: C: A341 CLOSE 3301 S: A341 OK CLOSE completed 3303 6.4.2. UNSELECT Command 3305 Arguments: none 3307 Responses: no specific responses for this command 3309 Result: OK - unselect completed, now in authenticated state 3310 BAD - no mailbox selected, or argument supplied but none 3311 permitted 3313 The UNSELECT command frees server's resources associated with the 3314 selected mailbox and returns the server to the authenticated state. 3315 This command performs the same actions as CLOSE, except that no 3316 messages are permanently removed from the currently selected mailbox. 3318 Example: C: A342 UNSELECT 3319 S: A342 OK Unselect completed 3321 6.4.3. EXPUNGE Command 3323 Arguments: none 3325 Responses: untagged responses: EXPUNGE 3327 Result: OK - expunge completed 3328 NO - expunge failure: can't expunge (e.g., permission 3329 denied) 3330 BAD - command unknown or arguments invalid 3332 The EXPUNGE command permanently removes all messages that have the 3333 \Deleted flag set from the currently selected mailbox. Before 3334 returning an OK to the client, an untagged EXPUNGE response is sent 3335 for each message that is removed. 3337 Example: C: A202 EXPUNGE 3338 S: * 3 EXPUNGE 3339 S: * 3 EXPUNGE 3340 S: * 5 EXPUNGE 3341 S: * 8 EXPUNGE 3342 S: A202 OK EXPUNGE completed 3344 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3345 set. See the description of the EXPUNGE response for further 3346 explanation. 3348 6.4.4. SEARCH Command 3350 Arguments: OPTIONAL result specifier 3351 OPTIONAL [CHARSET] specification 3352 searching criteria (one or more) 3354 Responses: OPTIONAL untagged response: ESEARCH 3356 Result: OK - search completed 3357 NO - search error: can't search that [CHARSET] or 3358 criteria 3359 BAD - command unknown or arguments invalid 3361 The SEARCH command searches the mailbox for messages that match the 3362 given searching criteria. 3364 The SEARCH command may contain result options. Result options 3365 control what kind of information is returned about messages matching 3366 the search criteria in an untagged ESEARCH response. If no result 3367 option is specified or empty list of options is specified "()", ALL 3368 is assumed (see below). The order of individual options is 3369 arbitrary. Individual options may contain parameters enclosed in 3370 parentheses (*). If an option has parameters, they consist of atoms 3371 and/or strings and/or lists in a specific order. Any options not 3372 defined by extensions that the server supports must be rejected with 3373 a BAD response. 3375 (*) - if an option has a mandatory parameter, which can always be 3376 represented as a number or a sequence-set, the option parameter does 3377 not need the enclosing (). See ABNF for more details. 3379 This document specifies the following result options: 3381 MIN 3383 Return the lowest message number/UID that satisfies the SEARCH 3384 criteria. 3386 If the SEARCH results in no matches, the server MUST NOT 3387 include the MIN result option in the ESEARCH response; however, 3388 it still MUST send the ESEARCH response. 3390 MAX 3392 Return the highest message number/UID that satisfies the SEARCH 3393 criteria. 3395 If the SEARCH results in no matches, the server MUST NOT 3396 include the MAX result option in the ESEARCH response; however, 3397 it still MUST send the ESEARCH response. 3399 ALL 3401 Return all message numbers/UIDs that satisfy the SEARCH 3402 criteria using the sequence-set syntax. Note, the client MUST 3403 NOT assume that messages/UIDs will be listed in any particular 3404 order. 3406 If the SEARCH results in no matches, the server MUST NOT 3407 include the ALL result option in the ESEARCH response; however, 3408 it still MUST send the ESEARCH response. 3410 COUNT Return number of the messages that satisfy the SEARCH 3411 criteria. This result option MUST always be included in the 3412 ESEARCH response. 3414 SAVE 3416 This option tells the server to remember the result of the 3417 SEARCH or UID SEARCH command (as well as any command based on 3418 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3419 internal variable that we will reference as the "search result 3420 variable". The client can use the "$" marker to reference the 3421 content of this internal variable. The "$" marker can be used 3422 instead of message sequence or UID sequence in order to 3423 indicate that the server should substitute it with the list of 3424 messages from the search result variable. Thus, the client can 3425 use the result of the latest remembered SEARCH command as a 3426 parameter to another command. See Section 6.4.4.1 for details 3427 on how the value of the search result variable is determined, 3428 how it is affected by other commands executed, and how SAVE 3429 return option interacts with other return options. 3431 In absence of any other SEARCH result option, the SAVE result 3432 option also suppresses any ESEARCH response that would have 3433 been otherwise returned by the SEARCH command. 3435 Note: future extensions to this document can allow servers to return 3436 multiple ESEARCH responses for a single extended SEARCH command. 3437 However all options specified above MUST result in a single ESEARCH 3438 response. These extensions will have to describe how results from 3439 multiple ESEARCH responses are to be amalgamated. 3441 Searching criteria consist of one or more search keys. 3443 When multiple keys are specified, the result is the intersection (AND 3444 function) of all the messages that match those keys. For example, 3445 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3446 deleted messages from Smith with INTERNALDATE greater than February 3447 1, 1994. A search key can also be a parenthesized list of one or 3448 more search keys (e.g., for use with the OR and NOT keys). 3450 Server implementations MAY exclude [MIME-IMB] body parts with 3451 terminal content media types other than TEXT and MESSAGE from 3452 consideration in SEARCH matching. 3454 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3455 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3456 [CHARSET] of the strings that appear in the search criteria. 3457 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3458 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3459 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3460 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3461 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3462 CHARSET UTF-8 is redundant. It is permitted for improved 3463 compatibility with existing IMAP4rev1 clients. 3465 If the server does not support the specified [CHARSET], it MUST 3466 return a tagged NO response (not a BAD). This response SHOULD 3467 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3468 supported by the server. 3470 In all search keys that use strings, a message matches the key if the 3471 string is a substring of the associated text. The matching SHOULD be 3472 case-insensitive for characters within ASCII range. Consider using 3473 [IMAP-I18N] for language-sensitive case-insensitive searching. Note 3474 that the empty string is a substring; this is useful when doing a 3475 HEADER search in order to test for a header field presence in the 3476 message. 3478 The defined search keys are as follows. Refer to the Formal Syntax 3479 section for the precise syntactic definitions of the arguments. 3481 Messages with message sequence numbers corresponding 3482 to the specified message sequence number set. 3484 ALL All messages in the mailbox; the default initial key for ANDing. 3486 ANSWERED Messages with the \Answered flag set. 3488 BCC Messages that contain the specified string in the 3489 envelope structure's BCC field. 3491 BEFORE Messages whose internal date (disregarding time and 3492 timezone) is earlier than the specified date. 3494 BODY Messages that contain the specified string in the body 3495 of the message. Unlike TEXT (see below), this doesn't match any 3496 header fields. 3498 CC Messages that contain the specified string in the 3499 envelope structure's CC field. 3501 DELETED Messages with the \Deleted flag set. 3503 DRAFT Messages with the \Draft flag set. 3505 FLAGGED Messages with the \Flagged flag set. 3507 FROM Messages that contain the specified string in the 3508 envelope structure's FROM field. 3510 HEADER Messages that have a header with the 3511 specified field-name (as defined in [RFC-5322]) and that contains 3512 the specified string in the text of the header (what comes after 3513 the colon). If the string to search is zero-length, this matches 3514 all messages that have a header line with the specified field-name 3515 regardless of the contents. Servers should use substring search 3516 for this SEARCH item, as clients can use it for automatic 3517 processing not initiated by end users. For example this can be 3518 used for searching for Message-ID or Content-Type header field 3519 values that need to be exact, or for searches in header fields 3520 that the IMAP server might not know anything about. 3522 KEYWORD Messages with the specified keyword flag set. 3524 LARGER Messages with an [RFC-5322] size larger than the 3525 specified number of octets. 3527 NOT Messages that do not match the specified search 3528 key. 3530 ON Messages whose internal date (disregarding time and 3531 timezone) is within the specified date. 3533 OR Messages that match either search 3534 key. 3536 SEEN Messages that have the \Seen flag set. 3538 SENTBEFORE Messages whose [RFC-5322] Date: header 3539 (disregarding time and timezone) is earlier than the specified 3540 date. 3542 SENTON Messages whose [RFC-5322] Date: header (disregarding 3543 time and timezone) is within the specified date. 3545 SENTSINCE Messages whose [RFC-5322] Date: header 3546 (disregarding time and timezone) is within or later than the 3547 specified date. 3549 SINCE Messages whose internal date (disregarding time and 3550 timezone) is within or later than the specified date. 3552 SMALLER Messages with an [RFC-5322] size smaller than the 3553 specified number of octets. 3555 SUBJECT Messages that contain the specified string in the 3556 envelope structure's SUBJECT field. 3558 TEXT Messages that contain the specified string in the 3559 header (including MIME header fields) or body of the message. 3561 TO Messages that contain the specified string in the 3562 envelope structure's TO field. 3564 UID Messages with unique identifiers corresponding to 3565 the specified unique identifier set. Sequence set ranges are 3566 permitted. 3568 UNANSWERED Messages that do not have the \Answered flag set. 3570 UNDELETED Messages that do not have the \Deleted flag set. 3572 UNDRAFT Messages that do not have the \Draft flag set. 3574 UNFLAGGED Messages that do not have the \Flagged flag set. 3576 UNKEYWORD Messages that do not have the specified keyword 3577 flag set. 3579 UNSEEN Messages that do not have the \Seen flag set. 3581 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3582 SINCE 1-Feb-1994 NOT FROM "Smith" 3583 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3584 S: A282 OK SEARCH completed 3586 Example: C: A283 SEARCH RETURN () FLAGGED 3587 SINCE 1-Feb-1994 NOT FROM "Smith" 3588 S: * ESEARCH (TAG "A283") ALL 2,10:11 3589 S: A283 OK SEARCH completed 3591 Example: C: A284 SEARCH TEXT "string not in mailbox" 3592 S: * ESEARCH (TAG "A284") 3593 S: A284 OK SEARCH completed 3594 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3595 S: + Ready for literal text 3596 C: XXXXXX 3597 S: * ESEARCH (TAG "A285") ALL 43 3598 S: A285 OK SEARCH completed 3600 Note: Since this document is restricted to 7-bit ASCII text, it is 3601 not possible to show actual UTF-8 data. The "XXXXXX" is a 3602 placeholder for what would be 6 octets of 8-bit data in an actual 3603 transaction. 3605 The following example demonstrates finding the first unseen message 3606 in the mailbox: 3608 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3609 S: * ESEARCH (TAG "A284") MIN 4 3610 S: A284 OK SEARCH completed 3612 The following example demonstrates that if the ESEARCH UID indicator 3613 is present, all data in the ESEARCH response is referring to UIDs; 3614 for example, the MIN result specifier will be followed by a UID. 3616 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3617 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3618 S: A285 OK SEARCH completed 3620 The following example demonstrates returning the number of deleted 3621 messages: 3623 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3624 S: * ESEARCH (TAG "A286") COUNT 15 3625 S: A286 OK SEARCH completed 3627 6.4.4.1. SAVE result option and SEARCH result variable 3629 Upon successful completion of a SELECT or an EXAMINE command (after 3630 the tagged OK response), the current search result variable is reset 3631 to the empty sequence. 3633 A successful SEARCH command with the SAVE result option sets the 3634 value of the search result variable to the list of messages found in 3635 the SEARCH command. For example, if no messages were found, the 3636 search result variable will contain the empty sequence. 3638 Any of the following SEARCH commands MUST NOT change the search 3639 result variable: 3641 a SEARCH command that caused the server to return the BAD tagged 3642 response, 3644 a SEARCH command with no SAVE result option that caused the server 3645 to return NO tagged response, 3647 a successful SEARCH command with no SAVE result option. 3649 A SEARCH command with the SAVE result option that caused the server 3650 to return the NO tagged response sets the value of the search result 3651 variable to the empty sequence. 3653 When a message listed in the search result variable is EXPUNGEd, it 3654 is automatically removed from the list. Implementors are reminded 3655 that if the server stores the list as a list of message numbers, it 3656 MUST automatically adjust them when notifying the client about 3657 expunged messages, as described in Section 7.4.1. 3659 If the server decides to send a new UIDVALIDITY value while the 3660 mailbox is opened, this causes resetting of the search variable to 3661 the empty sequence. 3663 Note that even if the "$" marker contains the empty sequence of 3664 messages, it must be treated by all commands accepting message sets 3665 as parameters as a valid, but non-matching list of messages. For 3666 example, the "FETCH $" command would return a tagged OK response and 3667 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3669 The SAVE result option doesn't change whether the server would return 3670 items corresponding to MIN, MAX, ALL, or COUNT result options. 3672 When the SAVE result option is combined with the MIN or MAX result 3673 option, and both ALL and COUNT result options are absent, the 3674 corresponding MIN/MAX is returned (if the search result is not 3675 empty), but the "$" marker would contain a single message as returned 3676 in the MIN/MAX return item. 3678 If the SAVE result option is combined with both MIN and MAX result 3679 options, and both ALL and COUNT result options are absent, the "$" 3680 marker would contain zero, one or two messages as returned in the 3681 MIN/MAX return items. 3683 If the SAVE result option is combined with the ALL and/or COUNT 3684 result option(s), the "$" marker would always contain all messages 3685 found by the SEARCH or UID SEARCH command. 3687 The following table summarizes the additional requirement on ESEARCH 3688 server implementations described in this section. 3690 +------------------------------+--------------------+ 3691 | Combination of Result option | "$" marker value | 3692 +------------------------------+--------------------+ 3693 | SAVE MIN | MIN | 3694 | SAVE MAX | MAX | 3695 | SAVE MIN MAX | MIN & MAX | 3696 | SAVE * [m] | all found messages | 3697 +------------------------------+--------------------+ 3699 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3700 and/or "MAX" 3702 Implementation note: server implementors should note that "$" can 3703 reference IMAP message sequences or UID sequences, depending on the 3704 context where it is used. For example, the "$" marker can be set as 3705 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3706 FETCH command (which accepts a UID sequence, not a message sequence), 3707 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3708 command and used as a parameter to a FETCH command (which accepts a 3709 message sequence, not a UID sequence). Server implementations need 3710 to automatically map the "$" marker value to message numbers or UIDs, 3711 depending on context where the "$" marker is used. 3713 6.4.4.2. Multiple Commands in Progress 3715 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3716 "$" marker creates direct dependency between the two commands. As 3717 directed by Section 5.5, a server MUST execute the two commands in 3718 the order they were received. 3720 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3721 command using the "$" marker, as long as this doesn't create an 3722 ambiguity, as described in by Section 5.5. Examples 7-9 in 3723 Section 6.4.4.4 explain this in more details. 3725 6.4.4.3. Refusing to Save Search Results 3727 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3728 for example, if an internal limit on the number of saved results is 3729 reached. In this case, the server MUST return a tagged NO response 3730 containing the NOTSAVED response code and set the search result 3731 variable to the empty sequence, as described in Section 6.4.4.1. 3733 6.4.4.4. Examples showing use of SAVE result option 3735 Only in this section: explanatory comments in examples that start 3736 with // are not part of the protocol. 3738 1) The following example demonstrates how the client can use the 3739 result of a SEARCH command to FETCH headers of interesting messages: 3741 Example 1: 3742 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3743 NOT FROM "Smith" 3744 S: A282 OK SEARCH completed, result saved 3745 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3746 S: * 2 FETCH (UID 14 ... 3747 S: * 84 FETCH (UID 100 ... 3748 S: * 882 FETCH (UID 1115 ... 3749 S: A283 OK completed 3751 The client can also pipeline the two commands: 3753 Example 2: 3754 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3755 NOT FROM "Smith" 3756 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3757 S: A282 OK SEARCH completed 3758 S: * 2 FETCH (UID 14 ... 3759 S: * 84 FETCH (UID 100 ... 3760 S: * 882 FETCH (UID 1115 ... 3761 S: A283 OK completed 3763 2) The following example demonstrates that the result of one SEARCH 3764 command can be used as input to another SEARCH command: 3766 Example 3: 3767 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3768 NOT FROM "Smith" 3769 S: A300 OK SEARCH completed 3770 C: A301 UID SEARCH UID $ SMALLER 4096 3771 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3772 S: A301 OK completed 3774 Note that the second command in Example 3 can be replaced with: 3775 C: A301 UID SEARCH $ SMALLER 4096 3776 and the result of the command would be the same. 3778 3) The following example shows that the "$" marker can be combined 3779 with other message numbers using the OR SEARCH criterion. 3781 Example 4: 3782 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3783 NOT FROM "Smith" 3784 S: P282 OK SEARCH completed 3785 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3786 C: YYYYYYYY 3787 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3788 S: P283 OK completed 3790 Note: Since this document format is restricted to 7-bit ASCII text, 3791 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3792 placeholder for what would be 8 octets of 8-bit data in an actual 3793 transaction. 3795 4) The following example demonstrates that a failed SEARCH sets the 3796 search result variable to the empty list. The server doesn't 3797 implement the KOI8-R charset. 3799 Example 5: 3800 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3801 NOT FROM "Smith" 3802 S: B282 OK SEARCH completed 3803 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3804 (OR $ 1,3000:3021) TEXT {4} 3805 C: XXXX 3806 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3807 //After this command the saved result variable contains 3808 //no messages. A client that wants to reissue the B283 3809 //SEARCH command with another CHARSET would have to reissue 3810 //the B282 command as well. One possible workaround for 3811 //this is to include the desired CHARSET parameter 3812 //in the earliest SEARCH RETURN (SAVE) command in a 3813 //sequence of related SEARCH commands, to cause 3814 //the earliest SEARCH in the sequence to fail. 3815 //A better approach might be to always use CHARSET UTF-8 3816 //instead. 3818 Note: Since this document format is restricted to 7-bit ASCII text, 3819 it is not possible to show actual KOI8-R data. The "XXXX" is a 3820 placeholder for what would be 4 octets of 8-bit data in an actual 3821 transaction. 3823 5) The following example demonstrates that it is not an error to use 3824 the "$" marker when it contains no messages. 3826 Example 6: 3827 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3828 NOT FROM "Eric" 3829 C: E283 COPY $ "Other Messages" 3830 //The "$" contains no messages 3831 S: E282 OK SEARCH completed 3832 S: E283 OK COPY completed, nothing copied 3834 Example 7: 3835 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3836 C: F283 COPY $ "Junk" 3837 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3838 S: F282 OK SEARCH completed 3839 S: F283 OK COPY completed 3840 S: F284 OK STORE completed 3842 Example 8: 3843 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3844 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3845 FROM "Eric" 3846 // The server can execute the two SEARCH commands 3847 // in any order, as they don't have any dependency. 3848 // For example, it may return: 3849 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3850 S: G283 OK SEARCH completed 3851 S: G282 OK SEARCH completed 3853 The following example demonstrates that the result of the second 3854 SEARCH RETURN (SAVE) always overrides the result of the first. 3856 Example 9: 3857 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3858 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3859 FROM "Eric" 3860 S: H282 OK SEARCH completed 3861 S: H283 OK SEARCH completed 3862 // At this point "$" would contain results of H283 3864 The following example demonstrates behavioral difference for 3865 different combinations of ESEARCH result options. 3867 Example 10: 3868 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3869 NOT FROM "Smith" 3870 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3871 //$ value hasn't changed 3872 S: C282 OK SEARCH completed 3874 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3875 NOT FROM "Smith" 3876 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3877 //$ value is 2,10:15,21 3878 S: C283 OK SEARCH completed 3880 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 3881 NOT FROM "Smith" 3882 S: * ESEARCH (TAG "C284") MIN 2 3883 //$ value is 2 3884 S: C284 OK SEARCH completed 3886 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 3887 12-Feb-2006 NOT FROM "Smith" 3888 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 3889 //$ value is 2,21 3890 S: C285 OK SEARCH completed 3892 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 3893 SINCE 12-Feb-2006 NOT FROM "Smith" 3894 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 3895 //$ value is 2,10:15,21 3896 S: C286 OK SEARCH completed 3898 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 3899 12-Feb-2006 NOT FROM "Smith" 3900 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 3901 //$ value is 2,10:15,21 3902 S: C286 OK SEARCH completed 3904 6.4.5. FETCH Command 3906 Arguments: sequence set 3907 message data item names or macro 3909 Responses: untagged responses: FETCH 3911 Result: OK - fetch completed 3912 NO - fetch error: can't fetch that data 3913 BAD - command unknown or arguments invalid 3915 The FETCH command retrieves data associated with a message in the 3916 mailbox. The data items to be fetched can be either a single atom or 3917 a parenthesized list. 3919 Most data items, identified in the formal syntax under the msg-att- 3920 static rule, are static and MUST NOT change for any particular 3921 message. Other data items, identified in the formal syntax under the 3922 msg-att-dynamic rule, MAY change, either as a result of a STORE 3923 command or due to external events. 3925 For example, if a client receives an ENVELOPE for a message when 3926 it already knows the envelope, it can safely ignore the newly 3927 transmitted envelope. 3929 There are three macros which specify commonly-used sets of data 3930 items, and can be used instead of data items. A macro must be used 3931 by itself, and not in conjunction with other macros or data items. 3933 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 3935 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 3937 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 3938 BODY) 3940 The currently defined data items that can be fetched are: 3942 BINARY[]<> 3944 Requests that the specified section be transmitted after 3945 performing Content-Transfer-Encoding-related decoding. 3947 The argument, if present, requests that a subset of 3948 the data be returned. The semantics of a partial FETCH BINARY 3949 command are the same as for a partial FETCH BODY command, with 3950 the exception that the arguments refer to the DECODED 3951 section data. 3953 BINARY.PEEK[]<> An alternate form of 3954 BINARY[] that does not implicitly set the \Seen 3955 flag. 3957 BINARY.SIZE[] 3959 Requests the decoded size of the section (i.e., the size to 3960 expect in response to the corresponding FETCH BINARY request). 3962 Note: client authors are cautioned that this might be an 3963 expensive operation for some server implementations. 3964 Needlessly issuing this request could result in degraded 3965 performance due to servers having to calculate the value every 3966 time the request is issued. 3968 BODY Non-extensible form of BODYSTRUCTURE. 3970 BODY[
]<> 3972 The text of a particular body section. The section 3973 specification is a set of zero or more part specifiers 3974 delimited by periods. A part specifier is either a part number 3975 or one of the following: HEADER, HEADER.FIELDS, 3976 HEADER.FIELDS.NOT, MIME, and TEXT. An empty section 3977 specification refers to the entire message, including the 3978 header. 3980 Every message has at least one part number. Non-[MIME-IMB] 3981 messages, and non-multipart [MIME-IMB] messages with no 3982 encapsulated message, only have a part 1. 3984 Multipart messages are assigned consecutive part numbers, as 3985 they occur in the message. If a particular part is of type 3986 message or multipart, its parts MUST be indicated by a period 3987 followed by the part number within that nested multipart part. 3989 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested 3990 part numbers, referring to parts of the MESSAGE part's body. 3992 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 3993 specifiers can be the sole part specifier or can be prefixed by 3994 one or more numeric part specifiers, provided that the numeric 3995 part specifier refers to a part of type MESSAGE/RFC822 or 3996 MESSAGE/GLOBAL. The MIME part specifier MUST be prefixed by 3997 one or more numeric part specifiers. 3999 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part 4000 specifiers refer to the [RFC-5322] header of the message or of 4001 an encapsulated [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL 4002 message. HEADER.FIELDS and HEADER.FIELDS.NOT are followed by a 4003 list of field-name (as defined in [RFC-5322]) names, and return 4004 a subset of the header. The subset returned by HEADER.FIELDS 4005 contains only those header fields with a field-name that 4006 matches one of the names in the list; similarly, the subset 4007 returned by HEADER.FIELDS.NOT contains only the header fields 4008 with a non-matching field-name. The field-matching is ASCII 4009 range case-insensitive but otherwise exact. Subsetting does 4010 not exclude the [RFC-5322] delimiting blank line between the 4011 header and the body; the blank line is included in all header 4012 fetches, except in the case of a message which has no body and 4013 no blank line. 4015 The MIME part specifier refers to the [MIME-IMB] header for 4016 this part. 4018 The TEXT part specifier refers to the text body of the message, 4019 omitting the [RFC-5322] header. 4021 Here is an example of a complex message with some of its 4022 part specifiers: 4024 HEADER ([RFC-5322] header of the message) 4025 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4026 1 TEXT/PLAIN 4027 2 APPLICATION/OCTET-STREAM 4028 3 MESSAGE/RFC822 4029 3.HEADER ([RFC-5322] header of the message) 4030 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4031 3.1 TEXT/PLAIN 4032 3.2 APPLICATION/OCTET-STREAM 4033 4 MULTIPART/MIXED 4034 4.1 IMAGE/GIF 4035 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4036 4.2 MESSAGE/RFC822 4037 4.2.HEADER ([RFC-5322] header of the message) 4038 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4039 4.2.1 TEXT/PLAIN 4040 4.2.2 MULTIPART/ALTERNATIVE 4041 4.2.2.1 TEXT/PLAIN 4042 4.2.2.2 TEXT/RICHTEXT 4044 It is possible to fetch a substring of the designated text. 4045 This is done by appending an open angle bracket ("<"), the 4046 octet position of the first desired octet, a period, the 4047 maximum number of octets desired, and a close angle bracket 4048 (">") to the part specifier. If the starting octet is beyond 4049 the end of the text, an empty string is returned. 4051 Any partial fetch that attempts to read beyond the end of the 4052 text is truncated as appropriate. A partial fetch that starts 4053 at octet 0 is returned as a partial fetch, even if this 4054 truncation happened. 4056 Note: This means that BODY[]<0.2048> of a 1500-octet message 4057 will return BODY[]<0> with a literal of size 1500, not 4058 BODY[]. 4060 Note: A substring fetch of a HEADER.FIELDS or 4061 HEADER.FIELDS.NOT part specifier is calculated after 4062 subsetting the header. 4064 The \Seen flag is implicitly set; if this causes the flags to 4065 change, they SHOULD be included as part of the FETCH responses. 4067 BODY.PEEK[
]<> An alternate form of BODY[
] 4068 that does not implicitly set the \Seen flag. 4070 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4071 computed by the server by parsing the [MIME-IMB] header fields in 4072 the [RFC-5322] header and [MIME-IMB] headers. 4074 ENVELOPE The envelope structure of the message. This is computed by 4075 the server by parsing the [RFC-5322] header into the component 4076 parts, defaulting various fields as necessary. 4078 FLAGS The flags that are set for this message. 4080 INTERNALDATE The internal date of the message. 4082 RFC822.SIZE The [RFC-5322] size of the message. 4084 UID The unique identifier for the message. 4086 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4087 S: * 2 FETCH .... 4088 S: * 3 FETCH .... 4089 S: * 4 FETCH .... 4090 S: A654 OK FETCH completed 4092 6.4.6. STORE Command 4094 Arguments: sequence set 4095 message data item name 4096 value for message data item 4098 Responses: untagged responses: FETCH 4100 Result: OK - store completed 4101 NO - store error: can't store that data 4102 BAD - command unknown or arguments invalid 4104 The STORE command alters data associated with a message in the 4105 mailbox. Normally, STORE will return the updated value of the data 4106 with an untagged FETCH response. A suffix of ".SILENT" in the data 4107 item name prevents the untagged FETCH, and the server SHOULD assume 4108 that the client has determined the updated value itself or does not 4109 care about the updated value. 4111 Note: Regardless of whether or not the ".SILENT" suffix was used, 4112 the server SHOULD send an untagged FETCH response if a change to a 4113 message's flags from an external source is observed. The intent 4114 is that the status of the flags is determinate without a race 4115 condition. 4117 The currently defined data items that can be stored are: 4119 FLAGS Replace the flags for the message with the 4120 argument. The new value of the flags is returned as if a FETCH of 4121 those flags was done. 4123 FLAGS.SILENT Equivalent to FLAGS, but without returning 4124 a new value. 4126 +FLAGS Add the argument to the flags for the message. 4127 The new value of the flags is returned as if a FETCH of those 4128 flags was done. 4130 +FLAGS.SILENT Equivalent to +FLAGS, but without 4131 returning a new value. 4133 -FLAGS Remove the argument from the flags for the 4134 message. The new value of the flags is returned as if a FETCH of 4135 those flags was done. 4137 -FLAGS.SILENT Equivalent to -FLAGS, but without 4138 returning a new value. 4140 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4141 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4142 S: * 3 FETCH (FLAGS (\Deleted)) 4143 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4144 S: A003 OK STORE completed 4146 6.4.7. COPY Command 4148 Arguments: sequence set 4149 mailbox name 4151 Responses: no specific responses for this command 4152 Result: OK - copy completed 4153 NO - copy error: can't copy those messages or to that 4154 name 4155 BAD - command unknown or arguments invalid 4157 The COPY command copies the specified message(s) to the end of the 4158 specified destination mailbox. The flags and internal date of the 4159 message(s) SHOULD be preserved in the copy. 4161 If the destination mailbox does not exist, a server SHOULD return an 4162 error. It SHOULD NOT automatically create the mailbox. Unless it is 4163 certain that the destination mailbox can not be created, the server 4164 MUST send the response code "[TRYCREATE]" as the prefix of the text 4165 of the tagged NO response. This gives a hint to the client that it 4166 can attempt a CREATE command and retry the COPY if the CREATE is 4167 successful. 4169 If the COPY command is unsuccessful for any reason, server 4170 implementations MUST restore the destination mailbox to its state 4171 before the COPY attempt. 4173 On successful completion of a COPY, the server SHOULD return a 4174 COPYUID response code. 4176 In the case of a mailbox that has permissions set so that the client 4177 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4178 SHOULD NOT send an COPYUID response code as it would disclose 4179 information about the mailbox. 4181 In the case of a mailbox that has UIDNOTSTICKY status (see the 4182 UIDNOTSTICKY response code), the server MAY omit the COPYUID response 4183 code as it is not meaningful. 4185 If the server does not return the COPYUID response code, the client 4186 can discover this information by selecting the destination mailbox. 4187 The location of messages placed in the destination mailbox by COPY 4188 can be determined by using FETCH and/or SEARCH commands (e.g., for 4189 Message-ID). 4191 Example: C: A003 COPY 2:4 MEETING 4192 S: A003 OK COPY completed 4194 6.4.8. MOVE Command 4196 Arguments: sequence set 4197 mailbox name 4199 Responses: no specific responses for this command 4200 Result: OK - move completed 4201 NO - move error: can't move those messages or to that 4202 name 4203 BAD - command unknown or arguments invalid 4205 The MOVE command moves the specified message(s) to the end of the 4206 specified destination mailbox. The flags and internal date of the 4207 message(s) SHOULD be preserved. 4209 This means that a new message is created in the target mailbox with a 4210 new UID, the original message is removed from the source mailbox, and 4211 it appears to the client as a single action. This has the same 4212 effect for each message as this sequence: 4214 1. [UID] COPY 4216 2. [UID] STORE +FLAGS.SILENT \DELETED 4218 3. UID EXPUNGE 4220 Although the effect of the MOVE is the same as the preceding steps, 4221 the semantics are not identical: The intermediate states produced by 4222 those steps do not occur, and the response codes are different. In 4223 particular, though the COPY and EXPUNGE response codes will be 4224 returned, response codes for a STORE MUST NOT be generated and the 4225 \Deleted flag MUST NOT be set for any message. 4227 Because a MOVE applies to a set of messages, it might fail partway 4228 through the set. Regardless of whether the command is successful in 4229 moving the entire set, each individual message SHOULD either be moved 4230 or unaffected. The server MUST leave each message in a state where 4231 it is in at least one of the source or target mailboxes (no message 4232 can be lost or orphaned). The server SHOULD NOT leave any message in 4233 both mailboxes (it would be bad for a partial failure to result in a 4234 bunch of duplicate messages). This is true even if the server 4235 returns a tagged NO response to the command. 4237 Because of the similarity of MOVE to COPY, extensions that affect 4238 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4239 (see Section 7.1), as well as those defined by extensions, are sent 4240 as appropriate. 4242 Servers SHOULD send COPYUID in response to a UID MOVE (see 4243 Section 6.4.9) command. For additional information see Section 7.1. 4245 Servers are also advised to send the COPYUID response code in an 4246 untagged OK before sending EXPUNGE or moved responses. (Sending 4247 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4248 means that clients first receive an EXPUNGE for a message and 4249 afterwards COPYUID for the same message. It can be unnecessarily 4250 difficult to process that sequence usefully.) 4252 An example: 4253 C: a UID MOVE 42:69 foo 4254 S: * OK [COPYUID 432432 42:69 1202:1229] 4255 S: * 22 EXPUNGE 4256 S: (more expunges) 4257 S: a OK Done 4259 Note that the server may send unrelated EXPUNGE responses as well, if 4260 any happen to have been expunged at the same time; this is normal 4261 IMAP operation. 4263 Note that moving a message to the currently selected mailbox (that 4264 is, where the source and target mailboxes are the same) is allowed 4265 when copying the message to the currently selected mailbox is 4266 allowed. 4268 The server may send EXPUNGE responses before the tagged response, so 4269 the client cannot safely send more commands with message sequence 4270 number arguments while the server is processing MOVE. 4272 MOVE and UID MOVE can be pipelined with other commands, but care has 4273 to be taken. Both commands modify sequence numbers and also allow 4274 unrelated EXPUNGE responses. The renumbering of other messages in 4275 the source mailbox following any EXPUNGE response can be surprising 4276 and makes it unsafe to pipeline any command that relies on message 4277 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4278 pipelined with a command that might cause message renumbering. See 4279 Section 5.5, for more information about ambiguities as well as 4280 handling requirements for both clients and servers. 4282 6.4.9. UID Command 4284 Arguments: command name 4285 command arguments 4287 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4289 Result: OK - UID command completed 4290 NO - UID command error 4291 BAD - command unknown or arguments invalid 4293 The UID command has three forms. In the first form, it takes as its 4294 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4295 appropriate for the associated command. However, the numbers in the 4296 sequence set argument are unique identifiers instead of message 4297 sequence numbers. Sequence set ranges are permitted, but there is no 4298 guarantee that unique identifiers will be contiguous. 4300 A non-existent unique identifier is ignored without any error message 4301 generated. Thus, it is possible for a UID FETCH command to return an 4302 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4303 OK without performing any operations. 4305 In the second form, the UID command takes an EXPUNGE command with an 4306 extra parameter the specified a sequence set of UIDs to operate on. 4307 The UID EXPUNGE command permanently removes all messages that both 4308 have the \Deleted flag set and have a UID that is included in the 4309 specified sequence set from the currently selected mailbox. If a 4310 message either does not have the \Deleted flag set or has a UID that 4311 is not included in the specified sequence set, it is not affected. 4313 UID EXPUNGE is particularly useful for disconnected use clients. 4314 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4315 the server, the client can ensure that it does not inadvertantly 4316 remove any messages that have been marked as \Deleted by other 4317 clients between the time that the client was last connected and 4318 the time the client resynchronizes. 4320 Example: C: A003 UID EXPUNGE 3000:3002 4321 S: * 3 EXPUNGE 4322 S: * 3 EXPUNGE 4323 S: * 3 EXPUNGE 4324 S: A003 OK UID EXPUNGE completed 4326 In the third form, the UID command takes a SEARCH command with SEARCH 4327 command arguments. The interpretation of the arguments is the same 4328 as with SEARCH; however, the numbers returned in a ESEARCH response 4329 for a UID SEARCH command are unique identifiers instead of message 4330 sequence numbers. Also, the corresponding ESEARCH response MUST 4331 include the UID indicator. For example, the command UID SEARCH 1:100 4332 UID 443:557 returns the unique identifiers corresponding to the 4333 intersection of two sequence sets, the message sequence number range 4334 1:100 and the UID range 443:557. 4336 Note: in the above example, the UID range 443:557 appears. The 4337 same comment about a non-existent unique identifier being ignored 4338 without any error message also applies here. Hence, even if 4339 neither UID 443 or 557 exist, this range is valid and would 4340 include an existing UID 495. 4342 Also note that a UID range of 559:* always includes the UID of the 4343 last message in the mailbox, even if 559 is higher than any 4344 assigned UID value. This is because the contents of a range are 4345 independent of the order of the range endpoints. Thus, any UID 4346 range with * as one of the endpoints indicates at least one 4347 message (the message with the highest numbered UID), unless the 4348 mailbox is empty. 4350 The number after the "*" in an untagged FETCH or EXPUNGE response is 4351 always a message sequence number, not a unique identifier, even for a 4352 UID command response. However, server implementations MUST 4353 implicitly include the UID message data item as part of any FETCH 4354 response caused by a UID command, regardless of whether a UID was 4355 specified as a message data item to the FETCH. 4357 Note: The rule about including the UID message data item as part of a 4358 FETCH response primarily applies to the UID FETCH and UID STORE 4359 commands, including a UID FETCH command that does not include UID as 4360 a message data item. Although it is unlikely that the other UID 4361 commands will cause an untagged FETCH, this rule applies to these 4362 commands as well. 4364 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4365 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4366 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4367 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4368 S: A999 OK UID FETCH completed 4370 6.5. Client Commands - Experimental/Expansion 4372 6.5.1. X Command 4374 Arguments: implementation defined 4376 Responses: implementation defined 4378 Result: OK - command completed 4379 NO - failure 4380 BAD - command unknown or arguments invalid 4382 Any command prefixed with an X is an experimental command. Commands 4383 which are not part of this specification, a standard or standards- 4384 track revision of this specification, or an IESG-approved 4385 experimental protocol, MUST use the X prefix. 4387 Any added untagged responses issued by an experimental command MUST 4388 also be prefixed with an X. Server implementations MUST NOT send any 4389 such untagged responses, unless the client requested it by issuing 4390 the associated experimental command. 4392 Example: C: a441 CAPABILITY 4393 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4394 S: a441 OK CAPABILITY completed 4395 C: A442 XPIG-LATIN 4396 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4397 S: A442 OK XPIG-LATIN ompleted-cay 4399 7. Server Responses 4401 Server responses are in three forms: status responses, server data, 4402 and command continuation request. The information contained in a 4403 server response, identified by "Contents:" in the response 4404 descriptions below, is described by function, not by syntax. The 4405 precise syntax of server responses is described in the Formal Syntax 4406 section. 4408 The client MUST be prepared to accept any response at all times. 4410 Status responses can be tagged or untagged. Tagged status responses 4411 indicate the completion result (OK, NO, or BAD status) of a client 4412 command, and have a tag matching the command. 4414 Some status responses, and all server data, are untagged. An 4415 untagged response is indicated by the token "*" instead of a tag. 4416 Untagged status responses indicate server greeting, or server status 4417 that does not indicate the completion of a command (for example, an 4418 impending system shutdown alert). For historical reasons, untagged 4419 server data responses are also called "unsolicited data", although 4420 strictly speaking, only unilateral server data is truly 4421 "unsolicited". 4423 Certain server data MUST be recorded by the client when it is 4424 received; this is noted in the description of that data. Such data 4425 conveys critical information which affects the interpretation of all 4426 subsequent commands and responses (e.g., updates reflecting the 4427 creation or destruction of messages). 4429 Other server data SHOULD be recorded for later reference; if the 4430 client does not need to record the data, or if recording the data has 4431 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4432 in progress), the data SHOULD be ignored. 4434 An example of unilateral untagged server data occurs when the IMAP 4435 connection is in the selected state. In the selected state, the 4436 server checks the mailbox for new messages as part of command 4437 execution. Normally, this is part of the execution of every command; 4438 hence, a NOOP command suffices to check for new messages. If new 4439 messages are found, the server sends untagged EXISTS response 4440 reflecting the new size of the mailbox. Server implementations that 4441 offer multiple simultaneous access to the same mailbox SHOULD also 4442 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4443 another agent changes the state of any message flags or expunges any 4444 messages. 4446 Command continuation request responses use the token "+" instead of a 4447 tag. These responses are sent by the server to indicate acceptance 4448 of an incomplete client command and readiness for the remainder of 4449 the command. 4451 7.1. Server Responses - Status Responses 4453 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4454 can be tagged or untagged. PREAUTH and BYE are always untagged. 4456 Status responses MAY include an OPTIONAL "response code". A response 4457 code consists of data inside square brackets in the form of an atom, 4458 possibly followed by a space and arguments. The response code 4459 contains additional information or status codes for client software 4460 beyond the OK/NO/BAD condition, and are defined when there is a 4461 specific action that a client can take based upon the additional 4462 information. 4464 The currently defined response codes are: 4466 ALERT 4468 The human-readable text contains a special alert that MUST be 4469 presented to the user in a fashion that calls the user's 4470 attention to the message. 4472 ALREADYEXISTS 4474 The operation attempts to create something that already exists, 4475 such as when the CREATE or RENAME directories attempt to create 4476 a mailbox and there is already one of that name. 4478 C: o356 RENAME this that 4479 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4481 APPENDUID 4483 Followed by the UIDVALIDITY of the destination mailbox and the 4484 UID assigned to the appended message in the destination 4485 mailbox, indicates that the message has been appended to the 4486 destination mailbox with that UID. 4488 If the server also supports the [MULTIAPPEND] extension, and if 4489 multiple messages were appended in the APPEND command, then the 4490 second value is a UID set containing the UIDs assigned to the 4491 appended messages, in the order they were transmitted in the 4492 APPEND command. This UID set may not contain extraneous UIDs 4493 or the symbol "*". 4495 Note: the UID set form of the APPENDUID response code MUST 4496 NOT be used if only a single message was appended. In 4497 particular, a server MUST NOT send a range such as 123:123. 4498 This is because a client that does not support [MULTIAPPEND] 4499 expects only a single UID and not a UID set. 4501 UIDs are assigned in strictly ascending order in the mailbox 4502 (refer to Section 2.3.1.1); note that a range of 12:10 is 4503 exactly equivalent to 10:12 and refers to the sequence 4504 10,11,12. 4506 This response code is returned in a tagged OK response to the 4507 APPEND command. 4509 AUTHENTICATIONFAILED 4511 Authentication failed for some reason on which the server is 4512 unwilling to elaborate. Typically, this includes "unknown 4513 user" and "bad password". 4515 This is the same as not sending any response code, except that 4516 when a client sees AUTHENTICATIONFAILED, it knows that the 4517 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4518 trying the same login/password again later. 4520 C: b LOGIN "fred" "foo" 4521 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4523 AUTHORIZATIONFAILED 4525 Authentication succeeded in using the authentication identity, 4526 but the server cannot or will not allow the authentication 4527 identity to act as the requested authorization identity. This 4528 is only applicable when the authentication and authorization 4529 identities are different. 4531 C: c1 AUTHENTICATE PLAIN 4532 [...] 4533 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4534 C: c2 AUTHENTICATE PLAIN 4535 [...] 4536 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4538 BADCHARSET 4540 Optionally followed by a parenthesized list of charsets. A 4541 SEARCH failed because the given charset is not supported by 4542 this implementation. If the optional list of charsets is 4543 given, this lists the charsets that are supported by this 4544 implementation. 4546 CANNOT 4548 The operation violates some invariant of the server and can 4549 never succeed. 4551 C: l create "///////" 4552 S: l NO [CANNOT] Adjacent slashes are not supported 4554 CAPABILITY 4556 Followed by a list of capabilities. This can appear in the 4557 initial OK or PREAUTH response to transmit an initial 4558 capabilities list. It can also appear in tagged responses to 4559 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4560 a client to send a separate CAPABILITY command if it recognizes 4561 this response. 4563 CLIENTBUG 4565 The server has detected a client bug. This can accompany all 4566 of OK, NO, and BAD, depending on what the client bug is. 4568 C: k1 select "/archive/projects/experiment-iv" 4569 [...] 4570 S: k1 OK [READ-ONLY] Done 4571 C: k2 status "/archive/projects/experiment-iv" (messages) 4572 [...] 4573 S: k2 OK [CLIENTBUG] Done 4575 CLOSED 4577 The CLOSED response code has no parameters. A server return 4578 the CLOSED response code when the currently selected mailbox is 4579 closed implicitly using the SELECT/EXAMINE command on another 4580 mailbox. The CLOSED response code serves as a boundary between 4581 responses for the previously opened mailbox (which was closed) 4582 and the newly selected mailbox; all responses before the CLOSED 4583 response code relate to the mailbox that was closed, and all 4584 subsequent responses relate to the newly opened mailbox. 4586 There is no need to return the CLOSED response code on 4587 completion of the CLOSE or the UNSELECT command (or similar), 4588 whose purpose is to close the currently selected mailbox 4589 without opening a new one. 4591 The server MAY also return an unsolicited CLOSED response code 4592 when it wants to force the client to return to authenticated 4593 state. For example, the server can do that when the mailbox 4594 requires repairs or is deleted in another session. 4596 CONTACTADMIN 4598 The user should contact the system administrator or support 4599 desk. 4601 C: e login "fred" "foo" 4602 S: e OK [CONTACTADMIN] 4604 COPYUID 4606 Followed by the UIDVALIDITY of the destination mailbox, a UID 4607 set containing the UIDs of the message(s) in the source mailbox 4608 that were copied to the destination mailbox and containing the 4609 UIDs assigned to the copied message(s) in the destination 4610 mailbox, indicates that the message(s) have been copied to the 4611 destination mailbox with the stated UID(s). 4613 The source UID set is in the order the message(s) were copied; 4614 the destination UID set corresponds to the source UID set and 4615 is in the same order. Neither of the UID sets may contain 4616 extraneous UIDs or the symbol "*". 4618 UIDs are assigned in strictly ascending order in the mailbox 4619 (refer to Section 2.3.1.1); note that a range of 12:10 is 4620 exactly equivalent to 10:12 and refers to the sequence 4621 10,11,12. 4623 This response code is returned in a tagged OK response to the 4624 COPY command. 4626 CORRUPTION 4628 The server discovered that some relevant data (e.g., the 4629 mailbox) are corrupt. This response code does not include any 4630 information about what's corrupt, but the server can write that 4631 to its logfiles. 4633 C: i select "/archive/projects/experiment-iv" 4634 S: i NO [CORRUPTION] Cannot open mailbox 4636 EXPIRED 4638 Either authentication succeeded or the server no longer had the 4639 necessary data; either way, access is no longer permitted using 4640 that passphrase. The client or user should get a new 4641 passphrase. 4643 C: d login "fred" "foo" 4644 S: d NO [EXPIRED] That password isn't valid any more 4646 EXPUNGEISSUED 4648 Someone else has issued an EXPUNGE for the same mailbox. The 4649 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4650 discusses this subject in depth. 4652 C: h search from fred@example.com 4653 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4654 S: h OK [EXPUNGEISSUED] Search completed 4656 HASCHILDREN 4658 The mailbox delete operation failed because the mailbox has one 4659 or more children and the server doesn't allow deletion of 4660 mailboxes with children. 4662 C: m356 DELETE Notes 4663 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4664 to be deleted first 4666 INUSE 4668 An operation has not been carried out because it involves 4669 sawing off a branch someone else is sitting on. Someone else 4670 may be holding an exclusive lock needed for this operation, or 4671 the operation may involve deleting a resource someone else is 4672 using, typically a mailbox. 4674 The operation may succeed if the client tries again later. 4676 C: g delete "/archive/projects/experiment-iv" 4677 S: g NO [INUSE] Mailbox in use 4679 LIMIT 4681 The operation ran up against an implementation limit of some 4682 kind, such as the number of flags on a single message or the 4683 number of flags used in a mailbox. 4685 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4686 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4688 NONEXISTENT 4690 The operation attempts to delete something that does not exist. 4691 Similar to ALREADYEXISTS. 4693 C: p RENAME this that 4694 S: p NO [NONEXISTENT] No such mailbox 4696 NOPERM 4698 The access control system (e.g., Access Control List (ACL), see 4699 [RFC4314] does not permit this user to carry out an operation, 4700 such as selecting or creating a mailbox. 4702 C: f select "/archive/projects/experiment-iv" 4703 S: f NO [NOPERM] Access denied 4705 OVERQUOTA 4707 The user would be over quota after the operation. (The user 4708 may or may not be over quota already.) 4710 Note that if the server sends OVERQUOTA but doesn't support the 4711 IMAP QUOTA extension defined by [RFC2087], then there is a 4712 quota, but the client cannot find out what the quota is. 4714 C: n1 uid copy 1:* oldmail 4715 S: n1 NO [OVERQUOTA] Sorry 4717 C: n2 uid copy 1:* oldmail 4718 S: n2 OK [OVERQUOTA] You are now over your soft quota 4720 PARSE 4722 The human-readable text represents an error in parsing the 4723 [RFC-5322] header or [MIME-IMB] headers of a message in the 4724 mailbox. 4726 PERMANENTFLAGS 4728 Followed by a parenthesized list of flags, indicates which of 4729 the known flags the client can change permanently. Any flags 4730 that are in the FLAGS untagged response, but not the 4731 PERMANENTFLAGS list, can not be set permanently. The 4732 PERMANENTFLAGS list can also include the special flag \*, which 4733 indicates that it is possible to create new keywords by 4734 attempting to store those keywords in the mailbox. If the 4735 client attempts to STORE a flag that is not in the 4736 PERMANENTFLAGS list, the server will either ignore the change 4737 or store the state change for the remainder of the current 4738 session only. 4740 There is no need for a server that included the special flag \* 4741 to return a new PERMANENTFLAGS response code when a new keyword 4742 was successfully set on a message upon client request. However 4743 if the server has a limit on the number of different keywords 4744 that can be stored in a mailbox and that limit is reached, the 4745 server MUST send a new PERMANENTFLAGS response code without the 4746 special flag \*. 4748 PRIVACYREQUIRED 4750 The operation is not permitted due to a lack of privacy. If 4751 Transport Layer Security (TLS) is not in use, the client could 4752 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4754 C: d login "fred" "foo" 4755 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4757 C: d select inbox 4758 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4760 READ-ONLY 4762 The mailbox is selected read-only, or its access while selected 4763 has changed from read-write to read-only. 4765 READ-WRITE 4767 The mailbox is selected read-write, or its access while 4768 selected has changed from read-only to read-write. 4770 SERVERBUG 4771 The server encountered a bug in itself or violated one of its 4772 own invariants. 4774 C: j select "/archive/projects/experiment-iv" 4775 S: j NO [SERVERBUG] This should not happen 4777 TRYCREATE 4779 An APPEND or COPY attempt is failing because the target mailbox 4780 does not exist (as opposed to some other reason). This is a 4781 hint to the client that the operation can succeed if the 4782 mailbox is first created by the CREATE command. 4784 UIDNEXT 4786 Followed by a decimal number, indicates the next unique 4787 identifier value. Refer to Section 2.3.1.1 for more 4788 information. 4790 UIDNOTSTICKY 4792 The selected mailbox is supported by a mail store that does not 4793 support persistent UIDs; that is, UIDVALIDITY will be different 4794 each time the mailbox is selected. Consequently, APPEND or 4795 COPY to this mailbox will not return an APPENDUID or COPYUID 4796 response code. 4798 This response code is returned in an untagged NO response to 4799 the SELECT command. 4801 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4802 This facility exists to support legacy mail stores in which 4803 it is technically infeasible to support persistent UIDs. 4804 This should be avoided when designing new mail stores. 4806 UIDVALIDITY 4808 Followed by a decimal number, indicates the unique identifier 4809 validity value. Refer to Section 2.3.1.1 for more information. 4811 UNAVAILABLE 4813 Temporary failure because a subsystem is down. For example, an 4814 IMAP server that uses a Lightweight Directory Access Protocol 4815 (LDAP) or Radius server for authentication might use this 4816 response code when the LDAP/Radius server is down. 4818 C: a LOGIN "fred" "foo" 4819 S: a NO [UNAVAILABLE] User's backend down for maintenance 4821 UNKNOWN-CTE 4823 The server does not know how to decode the section's Content- 4824 Transfer-Encoding. 4826 Client implementations MUST ignore response codes that they do not 4827 recognize. 4829 7.1.1. OK Response 4831 Contents: OPTIONAL response code 4832 human-readable text 4834 The OK response indicates an information message from the server. 4835 When tagged, it indicates successful completion of the associated 4836 command. The human-readable text MAY be presented to the user as an 4837 information message. The untagged form indicates an information-only 4838 message; the nature of the information MAY be indicated by a response 4839 code. 4841 The untagged form is also used as one of three possible greetings at 4842 connection startup. It indicates that the connection is not yet 4843 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4845 Example: S: * OK IMAP4rev2 server ready 4846 C: A001 LOGIN fred blurdybloop 4847 S: * OK [ALERT] System shutdown in 10 minutes 4848 S: A001 OK LOGIN Completed 4850 7.1.2. NO Response 4852 Contents: OPTIONAL response code 4853 human-readable text 4855 The NO response indicates an operational error message from the 4856 server. When tagged, it indicates unsuccessful completion of the 4857 associated command. The untagged form indicates a warning; the 4858 command can still complete successfully. The human-readable text 4859 describes the condition. 4861 Example: C: A222 COPY 1:2 owatagusiam 4862 S: * NO Disk is 98% full, please delete unnecessary data 4863 S: A222 OK COPY completed 4864 C: A223 COPY 3:200 blurdybloop 4865 S: * NO Disk is 98% full, please delete unnecessary data 4866 S: * NO Disk is 99% full, please delete unnecessary data 4867 S: A223 NO COPY failed: disk is full 4869 7.1.3. BAD Response 4871 Contents: OPTIONAL response code 4872 human-readable text 4874 The BAD response indicates an error message from the server. When 4875 tagged, it reports a protocol-level error in the client's command; 4876 the tag indicates the command that caused the error. The untagged 4877 form indicates a protocol-level error for which the associated 4878 command can not be determined; it can also indicate an internal 4879 server failure. The human-readable text describes the condition. 4881 Example: C: ...very long command line... 4882 S: * BAD Command line too long 4883 C: ...empty line... 4884 S: * BAD Empty command line 4885 C: A443 EXPUNGE 4886 S: * BAD Disk crash, attempting salvage to a new disk! 4887 S: * OK Salvage successful, no data lost 4888 S: A443 OK Expunge completed 4890 7.1.4. PREAUTH Response 4892 Contents: OPTIONAL response code 4893 human-readable text 4895 The PREAUTH response is always untagged, and is one of three possible 4896 greetings at connection startup. It indicates that the connection 4897 has already been authenticated by external means; thus no LOGIN/ 4898 AUTHENTICATE command is needed. 4900 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 4902 7.1.5. BYE Response 4904 Contents: OPTIONAL response code 4905 human-readable text 4907 The BYE response is always untagged, and indicates that the server is 4908 about to close the connection. The human-readable text MAY be 4909 displayed to the user in a status report by the client. The BYE 4910 response is sent under one of four conditions: 4912 1. as part of a normal logout sequence. The server will close the 4913 connection after sending the tagged OK response to the LOGOUT 4914 command. 4916 2. as a panic shutdown announcement. The server closes the 4917 connection immediately. 4919 3. as an announcement of an inactivity autologout. The server 4920 closes the connection immediately. 4922 4. as one of three possible greetings at connection startup, 4923 indicating that the server is not willing to accept a connection 4924 from this client. The server closes the connection immediately. 4926 The difference between a BYE that occurs as part of a normal LOGOUT 4927 sequence (the first case) and a BYE that occurs because of a failure 4928 (the other three cases) is that the connection closes immediately in 4929 the failure case. In all cases the client SHOULD continue to read 4930 response data from the server until the connection is closed; this 4931 will ensure that any pending untagged or completion responses are 4932 read and processed. 4934 Example: S: * BYE Autologout; idle for too long 4936 7.2. Server Responses - Server and Mailbox Status 4938 These responses are always untagged. This is how server and mailbox 4939 status data are transmitted from the server to the client. Many of 4940 these responses typically result from a command with the same name. 4942 7.2.1. The ENABLED Response 4944 Contents: capability listing 4946 The ENABLED response occurs as a result of an ENABLE command. The 4947 capability listing contains a space-separated listing of capability 4948 names that the server supports and that were successfully enabled. 4949 The ENABLED response may contain no capabilities, which means that no 4950 extensions listed by the client were successfully enabled. 4952 7.2.2. CAPABILITY Response 4954 Contents: capability listing 4955 The CAPABILITY response occurs as a result of a CAPABILITY command. 4956 The capability listing contains a space-separated listing of 4957 capability names that the server supports. The capability listing 4958 MUST include the atom "IMAP4rev2". 4960 In addition, client and server implementations MUST implement the 4961 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 4962 capabilities. See the Security Considerations section for important 4963 information. 4965 A capability name which begins with "AUTH=" indicates that the server 4966 supports that particular authentication mechanism. 4968 The LOGINDISABLED capability indicates that the LOGIN command is 4969 disabled, and that the server will respond with a tagged NO response 4970 to any attempt to use the LOGIN command even if the user name and 4971 password are valid. An IMAP client MUST NOT issue the LOGIN command 4972 if the server advertises the LOGINDISABLED capability. 4974 Other capability names indicate that the server supports an 4975 extension, revision, or amendment to the IMAP4rev2 protocol. Server 4976 responses MUST conform to this document until the client issues a 4977 command that uses the associated capability. 4979 Capability names MUST either begin with "X" or be informational, 4980 experimental or standards-track IMAP4rev2 extensions, revisions, or 4981 amendments registered with IANA. A server SHOULD NOT offer 4982 unregistered or non-standard capability names, unless such names are 4983 prefixed with an "X". 4985 Client implementations SHOULD NOT require any capability name other 4986 than "IMAP4rev2", and MUST ignore any unknown capability names. 4988 A server MAY send capabilities automatically, by using the CAPABILITY 4989 response code in the initial PREAUTH or OK responses, and by sending 4990 an updated CAPABILITY response code in the tagged OK response as part 4991 of a successful authentication. It is unnecessary for a client to 4992 send a separate CAPABILITY command if it recognizes these automatic 4993 capabilities. 4995 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 4997 7.2.3. LIST Response 4999 Contents: name attributes 5000 hierarchy delimiter 5001 name 5002 OPTIONAL extension data 5004 The LIST response occurs as a result of a LIST command. It returns a 5005 single name that matches the LIST specification. There can be 5006 multiple LIST responses for a single LIST command. 5008 The following base mailbox name attributes are defined: 5010 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5011 name does not refer to an existing mailbox. Note that this 5012 attribute is not meaningful by itself, as mailbox names that match 5013 the canonical LIST pattern but don't exist must not be returned 5014 unless one of the two conditions listed below is also satisfied: 5016 1. The mailbox name also satisfies the selection criteria (for 5017 example, it is subscribed and the "SUBSCRIBED" selection 5018 option has been specified). 5020 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5021 at least one descendant mailbox name that does not match the 5022 LIST pattern and does match the selection criteria. 5024 In practice, this means that the "\NonExistent" attribute is 5025 usually returned with one or more of "\Subscribed", "\Remote", 5026 "\HasChildren", or the CHILDINFO extended data item. 5028 The "\NonExistent" attribute implies "\NoSelect". 5030 \Noinferiors It is not possible for any child levels of hierarchy to 5031 exist under this name; no child levels exist now and none can be 5032 created in the future. 5034 \Noselect It is not possible to use this name as a selectable 5035 mailbox. 5037 \HasChildren The presence of this attribute indicates that the 5038 mailbox has child mailboxes. A server SHOULD NOT set this 5039 attribute if there are child mailboxes and the user does not have 5040 permission to access any of them. In this case, \HasNoChildren 5041 SHOULD be used. In many cases, however, a server may not be able 5042 to efficiently compute whether a user has access to any child 5043 mailbox. Note that even though the \HasChildren attribute for a 5044 mailbox must be correct at the time of processing of the mailbox, 5045 a client must be prepared to deal with a situation when a mailbox 5046 is marked with the \HasChildren attribute, but no child mailbox 5047 appears in the response to the LIST command. This might happen, 5048 for example, due to children mailboxes being deleted or made 5049 inaccessible to the user (using access control) by another client 5050 before the server is able to list them. 5052 \HasNoChildren The presence of this attribute indicates that the 5053 mailbox has NO child mailboxes that are accessible to the 5054 currently authenticated user. 5056 \Marked The mailbox has been marked "interesting" by the server; the 5057 mailbox probably contains messages that have been added since the 5058 last time the mailbox was selected. 5060 \Unmarked The mailbox does not contain any additional messages since 5061 the last time the mailbox was selected. 5063 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5064 command. 5066 \Remote The mailbox is a remote mailbox. 5068 It is an error for the server to return both a \HasChildren and a 5069 \HasNoChildren attribute in the same LIST response. 5071 Note: the \HasNoChildren attribute should not be confused with the 5072 \NoInferiors attribute, which indicates that no child mailboxes 5073 exist now and none can be created in the future. 5075 If it is not feasible for the server to determine whether or not the 5076 mailbox is "interesting", the server SHOULD NOT send either \Marked 5077 or \Unmarked. The server MUST NOT send more than one of \Marked, 5078 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5079 these. 5081 In addition to the base mailbox name attributes defined above, an 5082 IMAP server MAY also include any or all of the following attributes 5083 that denote "role" (or "special-use") of a mailbox. These attributes 5084 are included along with base attributes defined above. A given 5085 mailbox may have none, one, or more than one of these attributes. In 5086 some cases, a special use is advice to a client about what to put in 5087 that mailbox. In other cases, it's advice to a client about what to 5088 expect to find there. 5090 \All This mailbox presents all messages in the user's message store. 5091 Implementations MAY omit some messages, such as, perhaps, those in 5092 \Trash and \Junk. When this special use is supported, it is 5093 almost certain to represent a virtual mailbox. 5095 \Archive This mailbox is used to archive messages. The meaning of 5096 an "archival" mailbox is server-dependent; typically, it will be 5097 used to get messages out of the inbox, or otherwise keep them out 5098 of the user's way, while still making them accessible. 5100 \Drafts This mailbox is used to hold draft messages -- typically, 5101 messages that are being composed but have not yet been sent. In 5102 some server implementations, this might be a virtual mailbox, 5103 containing messages from other mailboxes that are marked with the 5104 "\Draft" message flag. Alternatively, this might just be advice 5105 that a client put drafts here. 5107 \Flagged This mailbox presents all messages marked in some way as 5108 "important". When this special use is supported, it is likely to 5109 represent a virtual mailbox collecting messages (from other 5110 mailboxes) that are marked with the "\Flagged" message flag. 5112 \Junk This mailbox is where messages deemed to be junk mail are 5113 held. Some server implementations might put messages here 5114 automatically. Alternatively, this might just be advice to a 5115 client-side spam filter. 5117 \Sent This mailbox is used to hold copies of messages that have been 5118 sent. Some server implementations might put messages here 5119 automatically. Alternatively, this might just be advice that a 5120 client save sent messages here. 5122 \Trash This mailbox is used to hold messages that have been deleted 5123 or marked for deletion. In some server implementations, this 5124 might be a virtual mailbox, containing messages from other 5125 mailboxes that are marked with the "\Deleted" message flag. 5126 Alternatively, this might just be advice that a client that 5127 chooses not to use the IMAP "\Deleted" model should use this as 5128 its trash location. In server implementations that strictly 5129 expect the IMAP "\Deleted" model, this special use is likely not 5130 to be supported. 5132 All of special-use attributes are OPTIONAL, and any given server or 5133 message store may support any combination of the attributes, or none 5134 at all. In most cases, there will likely be at most one mailbox with 5135 a given attribute for a given user, but in some server or message 5136 store implementations it might be possible for multiple mailboxes to 5137 have the same special-use attribute. 5139 Special-use attributes are likely to be user-specific. User Adam 5140 might share his \Sent mailbox with user Barb, but that mailbox is 5141 unlikely to also serve as Barb's \Sent mailbox. 5143 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5144 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5146 The hierarchy delimiter is a character used to delimit levels of 5147 hierarchy in a mailbox name. A client can use it to create child 5148 mailboxes, and to search higher or lower levels of naming hierarchy. 5149 All children of a top-level hierarchy node MUST use the same 5150 separator character. A NIL hierarchy delimiter means that no 5151 hierarchy exists; the name is a "flat" name. 5153 The name represents an unambiguous left-to-right hierarchy, and MUST 5154 be valid for use as a reference in LIST command. Unless \Noselect or 5155 \NonExistent is indicated, the name MUST also be valid as an argument 5156 for commands, such as SELECT, that accept mailbox names. 5158 The name might be followed by an OPTIONAL series of extended fields, 5159 a parenthesized list of tagged data (also referred to as "extended 5160 data item"). The first element of an extended field is a tag, which 5161 identifies the type of data. [RFC5258] specified requirements on tag 5162 registration, in particular it said that "Tags MUST be registered 5163 with IANA". This document doesn't change that. See Section 9.5 of 5164 [RFC5258] for the registration template. The server MAY return data 5165 in the extended fields that was not directly solicited by the client 5166 in the corresponding LIST command. For example, the client can 5167 enable extra extended fields by using another IMAP extension that 5168 make use of the extended LIST responses. The client MUST ignore all 5169 extended fields it doesn't recognize. 5171 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5173 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5174 ("color" "red")) Sample "text") 5175 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5176 Sample ("text" "more text")) 5178 7.2.4. NAMESPACE Response 5180 Contents: the prefix and hierarchy delimiter to the server's 5181 Personal Namespace(s), Other Users' Namespace(s), and 5182 Shared Namespace(s) 5184 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5185 contains the prefix and hierarchy delimiter to the server's Personal 5186 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5187 the server wishes to expose. The response will contain a NIL for any 5188 namespace class that is not available. Namespace-Response-Extensions 5189 ABNF non terminal is defined for extensibility and MAY be included in 5190 the response. 5192 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5194 7.2.5. STATUS Response 5196 Contents: name 5197 status parenthesized list 5199 The STATUS response occurs as a result of an STATUS command. It 5200 returns the mailbox name that matches the STATUS specification and 5201 the requested mailbox status information. 5203 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5205 7.2.6. ESEARCH Response 5207 Contents: one or more search-return-data pairs 5209 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5210 command. 5212 The ESEARCH response starts with an optional search correlator. If 5213 it is missing, then the response was not caused by a particular IMAP 5214 command, whereas if it is present, it contains the tag of the command 5215 that caused the response to be returned. 5217 The search correlator is followed by an optional UID indicator. If 5218 this indicator is present, all data in the ESEARCH response refers to 5219 UIDs, otherwise all returned data refers to message numbers. 5221 The rest of the ESEARCH response contains one or more search data 5222 pairs. Each pair starts with unique return item name, followed by a 5223 space and the corresponding data. Search data pairs may be returned 5224 in any order. Unless specified otherwise by an extension, any return 5225 item name SHOULD appear only once in an ESEARCH response. 5227 [[TBD: describe the most common search data pairs returned.]] 5229 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5231 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5233 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5235 7.2.7. FLAGS Response 5237 Contents: flag parenthesized list 5239 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5240 The flag parenthesized list identifies the flags (at a minimum, the 5241 system-defined flags) that are applicable for this mailbox. Flags 5242 other than the system flags can also exist, depending on server 5243 implementation. 5245 The update from the FLAGS response MUST be recorded by the client. 5247 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5249 7.3. Server Responses - Mailbox Size 5251 These responses are always untagged. This is how changes in the size 5252 of the mailbox are transmitted from the server to the client. 5253 Immediately following the "*" token is a number that represents a 5254 message count. 5256 7.3.1. EXISTS Response 5258 Contents: none 5260 The EXISTS response reports the number of messages in the mailbox. 5261 This response occurs as a result of a SELECT or EXAMINE command, and 5262 if the size of the mailbox changes (e.g., new messages). 5264 The update from the EXISTS response MUST be recorded by the client. 5266 Example: S: * 23 EXISTS 5268 7.4. Server Responses - Message Status 5270 These responses are always untagged. This is how message data are 5271 transmitted from the server to the client, often as a result of a 5272 command with the same name. Immediately following the "*" token is a 5273 number that represents a message sequence number. 5275 7.4.1. EXPUNGE Response 5277 Contents: none 5279 The EXPUNGE response reports that the specified message sequence 5280 number has been permanently removed from the mailbox. The message 5281 sequence number for each successive message in the mailbox is 5282 immediately decremented by 1, and this decrement is reflected in 5283 message sequence numbers in subsequent responses (including other 5284 untagged EXPUNGE responses). 5286 The EXPUNGE response also decrements the number of messages in the 5287 mailbox; it is not necessary to send an EXISTS response with the new 5288 value. 5290 As a result of the immediate decrement rule, message sequence numbers 5291 that appear in a set of successive EXPUNGE responses depend upon 5292 whether the messages are removed starting from lower numbers to 5293 higher numbers, or from higher numbers to lower numbers. For 5294 example, if the last 5 messages in a 9-message mailbox are expunged, 5295 a "lower to higher" server will send five untagged EXPUNGE responses 5296 for message sequence number 5, whereas a "higher to lower server" 5297 will send successive untagged EXPUNGE responses for message sequence 5298 numbers 9, 8, 7, 6, and 5. 5300 An EXPUNGE response MUST NOT be sent when no command is in progress, 5301 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5302 is necessary to prevent a loss of synchronization of message sequence 5303 numbers between client and server. A command is not "in progress" 5304 until the complete command has been received; in particular, a 5305 command is not "in progress" during the negotiation of command 5306 continuation. 5308 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5309 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5310 during a UID command. 5312 The update from the EXPUNGE response MUST be recorded by the client. 5314 Example: S: * 44 EXPUNGE 5316 7.4.2. FETCH Response 5318 Contents: message data 5320 The FETCH response returns data about a message to the client. The 5321 data are pairs of data item names and their values in parentheses. 5322 This response occurs as the result of a FETCH or STORE command, as 5323 well as by unilateral server decision (e.g., flag updates). 5325 The current data items are: 5327 BINARY[]<> 5329 An or expressing the content of the 5330 specified section after removing any Content-Transfer-Encoding- 5331 related encoding. If is present it refers to the 5332 offset within the DECODED section data. 5334 If the domain of the decoded data is "8bit" and the data does 5335 not contain the NUL octet, the server SHOULD return the data in 5336 a instead of a ; this allows the client to 5337 determine if the "8bit" data contains the NUL octet without 5338 having to explicitly scan the data stream for for NULs. 5340 Messaging clients and servers have been notoriously lax in 5341 their adherence to the Internet CRLF convention for terminating 5342 lines of textual data (text/* media types) in Internet 5343 protocols. When sending data in BINARY[...] FETCH data item, 5344 servers MUST ensure that textual line-oriented sections are 5345 always transmitted using the IMAP4 CRLF line termination 5346 syntax, regardless of the underlying storage representation of 5347 the data on the server. 5349 If the server does not know how to decode the section's 5350 Content-Transfer-Encoding, it MUST fail the request and issue a 5351 "NO" response that contains the "UNKNOWN-CTE" response code. 5353 BINARY.SIZE[] 5355 The size of the section after removing any Content-Transfer- 5356 Encoding-related encoding. The value returned MUST match the 5357 size of the or that will be returned by 5358 the corresponding FETCH BINARY request. 5360 If the server does not know how to decode the section's 5361 Content-Transfer-Encoding, it MUST fail the request and issue a 5362 "NO" response that contains the "UNKNOWN-CTE" response code. 5364 BODY A form of BODYSTRUCTURE without extension data. 5366 BODY[
]<> 5368 A string expressing the body contents of the specified section. 5369 The string SHOULD be interpreted by the client according to the 5370 content transfer encoding, body type, and subtype. 5372 If the origin octet is specified, this string is a substring of 5373 the entire body contents, starting at that origin octet. This 5374 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5375 truncated. 5377 Note: The origin octet facility MUST NOT be used by a server 5378 in a FETCH response unless the client specifically requested 5379 it by means of a FETCH of a BODY[
]<> data 5380 item. 5382 8-bit textual data is permitted if a [CHARSET] identifier is 5383 part of the body parameter parenthesized list for this section. 5384 Note that headers (part specifiers HEADER or MIME, or the 5385 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5386 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5387 line between the header and the body is not affected by header 5388 line subsetting; the blank line is always included as part of 5389 header data, except in the case of a message which has no body 5390 and no blank line. 5392 Non-textual data such as binary data MUST be transfer encoded 5393 into a textual form, such as BASE64, prior to being sent to the 5394 client. To derive the original binary data, the client MUST 5395 decode the transfer encoded string. 5397 BODYSTRUCTURE 5399 A parenthesized list that describes the [MIME-IMB] body 5400 structure of a message. This is computed by the server by 5401 parsing the [MIME-IMB] header fields, defaulting various fields 5402 as necessary. 5404 For example, a simple text message of 48 lines and 2279 octets 5405 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5406 ASCII") NIL NIL "7BIT" 2279 48) 5408 Multiple parts are indicated by parenthesis nesting. Instead 5409 of a body type as the first element of the parenthesized list, 5410 there is a sequence of one or more nested body structures. The 5411 second element of the parenthesized list is the multipart 5412 subtype (mixed, digest, parallel, alternative, etc.). 5414 For example, a two part message consisting of a text and a 5415 BASE64-encoded text attachment can have a body structure of: 5416 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5417 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5418 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5419 "BASE64" 4554 73) "MIXED") 5421 Extension data follows the multipart subtype. Extension data 5422 is never returned with the BODY fetch, but can be returned with 5423 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5424 the defined order. The extension data of a multipart body part 5425 are in the following order: 5427 body parameter parenthesized list A parenthesized list of 5428 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5429 "bar" is the value of "foo", and "rag" is the value of 5430 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5431 parameter value continuations as described in [RFC2231], for 5432 example, if the message contains parameters "foo*0*" and 5433 "foo*1*", the server should RFC2231-decode them, concatenate 5434 and return the resulting value as "foo*". 5436 body disposition A parenthesized list, consisting of a 5437 disposition type string, followed by a parenthesized list of 5438 disposition attribute/value pairs as defined in 5439 [DISPOSITION]. Servers SHOULD decode parameter value 5440 continuations as described in [RFC2231]. 5442 body language A string or parenthesized list giving the body 5443 language value as defined in [LANGUAGE-TAGS]. 5445 body location A string giving the body content URI as defined 5446 in [LOCATION]. 5448 Any following extension data are not yet defined in this 5449 version of the protocol. Such extension data can consist of 5450 zero or more NILs, strings, numbers, or potentially nested 5451 parenthesized lists of such data. Client implementations that 5452 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5453 extension data. Server implementations MUST NOT send such 5454 extension data until it has been defined by a revision of this 5455 protocol. 5457 The basic fields of a non-multipart body part are in the 5458 following order: 5460 body type A string giving the content media type name as 5461 defined in [MIME-IMB]. 5463 body subtype A string giving the content subtype name as 5464 defined in [MIME-IMB]. 5466 body parameter parenthesized list A parenthesized list of 5467 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5468 "bar" is the value of "foo" and "rag" is the value of "baz"] 5469 as defined in [MIME-IMB]. 5471 body id A string giving the Content-ID header field value as 5472 defined in Section 7 of [MIME-IMB]. 5474 body description A string giving the Content-Description 5475 header field value as defined in Section 8 of [MIME-IMB]. 5477 body encoding A string giving the content transfer encoding as 5478 defined in Section 6 of [MIME-IMB]. 5480 body size A number giving the size of the body in octets. 5481 Note that this size is the size in its transfer encoding and 5482 not the resulting size after any decoding. 5484 A body type of type MESSAGE and subtype RFC822 contains, 5485 immediately after the basic fields, the envelope structure, 5486 body structure, and size in text lines of the encapsulated 5487 message. 5489 A body type of type TEXT contains, immediately after the basic 5490 fields, the size of the body in text lines. Note that this 5491 size is the size in its content transfer encoding and not the 5492 resulting size after any decoding. 5494 Extension data follows the basic fields and the type-specific 5495 fields listed above. Extension data is never returned with the 5496 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5497 Extension data, if present, MUST be in the defined order. 5499 The extension data of a non-multipart body part are in the 5500 following order: 5502 body MD5 A string giving the body MD5 value as defined in 5503 [MD5]. 5505 body disposition A parenthesized list with the same content 5506 and function as the body disposition for a multipart body 5507 part. 5509 body language A string or parenthesized list giving the body 5510 language value as defined in [LANGUAGE-TAGS]. 5512 body location A string giving the body content URI as defined 5513 in [LOCATION]. 5515 Any following extension data are not yet defined in this 5516 version of the protocol, and would be as described above under 5517 multipart extension data. 5519 ENVELOPE 5521 A parenthesized list that describes the envelope structure of a 5522 message. This is computed by the server by parsing the 5523 [RFC-5322] header into the component parts, defaulting various 5524 fields as necessary. 5526 The fields of the envelope structure are in the following 5527 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5528 reply-to, and message-id. The date, subject, in-reply-to, and 5529 message-id fields are strings. The from, sender, reply-to, to, 5530 cc, and bcc fields are parenthesized lists of address 5531 structures. 5533 An address structure is a parenthesized list that describes an 5534 electronic mail address. The fields of an address structure 5535 are in the following order: personal name, [SMTP] at-domain- 5536 list (source route, obs-route), mailbox name, and host name. 5538 [RFC-5322] group syntax is indicated by a special form of 5539 address structure in which the host name field is NIL. If the 5540 mailbox name field is also NIL, this is an end of group marker 5541 (semi-colon in RFC 822 syntax). If the mailbox name field is 5542 non-NIL, this is a start of group marker, and the mailbox name 5543 field holds the group name phrase. 5545 If the Date, Subject, In-Reply-To, and Message-ID header lines 5546 are absent in the [RFC-5322] header, the corresponding member 5547 of the envelope is NIL; if these header lines are present but 5548 empty the corresponding member of the envelope is the empty 5549 string. 5551 Note: some servers may return a NIL envelope member in the 5552 "present but empty" case. Clients SHOULD treat NIL and 5553 empty string as identical. 5555 Note: [RFC-5322] requires that all messages have a valid 5556 Date header. Therefore, the date member in the envelope can 5557 not be NIL or the empty string. 5559 Note: [RFC-5322] requires that the In-Reply-To and Message- 5560 ID headers, if present, have non-empty content. Therefore, 5561 the in-reply-to and message-id members in the envelope can 5562 not be the empty string. 5564 If the From, To, Cc, and Bcc header lines are absent in the 5565 [RFC-5322] header, or are present but empty, the corresponding 5566 member of the envelope is NIL. 5568 If the Sender or Reply-To lines are absent in the [RFC-5322] 5569 header, or are present but empty, the server sets the 5570 corresponding member of the envelope to be the same value as 5571 the from member (the client is not expected to know to do 5572 this). 5574 Note: [RFC-5322] requires that all messages have a valid 5575 From header. Therefore, the from, sender, and reply-to 5576 members in the envelope can not be NIL. 5578 FLAGS A parenthesized list of flags that are set for this message. 5580 INTERNALDATE A string representing the internal date of the message. 5582 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5584 UID A number expressing the unique identifier of the message. 5586 If the server chooses to send unsolicited FETCH responses, they MUST 5587 include UID FETCH item. Note that this is a new requirement when 5588 compared to RFC 3501. 5590 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5592 7.5. Server Responses - Command Continuation Request 5594 The command continuation request response is indicated by a "+" token 5595 instead of a tag. This form of response indicates that the server is 5596 ready to accept the continuation of a command from the client. The 5597 remainder of this response is a line of text. 5599 This response is used in the AUTHENTICATE command to transmit server 5600 data to the client, and request additional client data. This 5601 response is also used if an argument to any command is a 5602 synchronizing literal. 5604 The client is not permitted to send the octets of the synchronizing 5605 literal unless the server indicates that it is expected. This 5606 permits the server to process commands and reject errors on a line- 5607 by-line basis. The remainder of the command, including the CRLF that 5608 terminates a command, follows the octets of the literal. If there 5609 are any additional command arguments, the literal octets are followed 5610 by a space and those arguments. 5612 Example: C: A001 LOGIN {11} 5613 S: + Ready for additional command text 5614 C: FRED FOOBAR {7} 5615 S: + Ready for additional command text 5616 C: fat man 5617 S: A001 OK LOGIN completed 5618 C: A044 BLURDYBLOOP {102856} 5619 S: A044 BAD No such command as "BLURDYBLOOP" 5621 8. Sample IMAP4rev2 connection 5623 The following is a transcript of an IMAP4rev2 connection. A long 5624 line in this sample is broken for editorial clarity. 5626 S: * OK IMAP4rev2 Service Ready 5627 C: a001 login mrc secret 5628 S: a001 OK LOGIN completed 5629 C: a002 select inbox 5630 S: * 18 EXISTS 5631 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5632 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5633 S: a002 OK [READ-WRITE] SELECT completed 5634 C: a003 fetch 12 full 5635 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5636 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5637 "IMAP4rev2 WG mtg summary and minutes" 5638 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5639 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5640 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5641 ((NIL NIL "imap" "cac.washington.edu")) 5642 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5643 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5644 "") 5645 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5646 92)) 5647 S: a003 OK FETCH completed 5648 C: a004 fetch 12 body[header] 5649 S: * 12 FETCH (BODY[HEADER] {342} 5650 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5651 S: From: Terry Gray 5652 S: Subject: IMAP4rev2 WG mtg summary and minutes 5653 S: To: imap@cac.washington.edu 5654 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5655 S: Message-Id: 5656 S: MIME-Version: 1.0 5657 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5658 S: 5659 S: ) 5660 S: a004 OK FETCH completed 5661 C: a005 store 12 +flags \deleted 5662 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5663 S: a005 OK +FLAGS completed 5664 C: a006 logout 5665 S: * BYE IMAP4rev2 server terminating connection 5666 S: a006 OK LOGOUT completed 5667 9. Formal Syntax 5669 The following syntax specification uses the Augmented Backus-Naur 5670 Form (ABNF) notation as specified in [ABNF]. 5672 In the case of alternative or optional rules in which a later rule 5673 overlaps an earlier rule, the rule which is listed earlier MUST take 5674 priority. For example, "\Seen" when parsed as a flag is the \Seen 5675 flag name and not a flag-extension, even though "\Seen" can be parsed 5676 as a flag-extension. Some, but not all, instances of this rule are 5677 noted below. 5679 Note: [ABNF] rules MUST be followed strictly; in particular: 5681 (1) Except as noted otherwise, all alphabetic characters are case- 5682 insensitive. The use of upper or lower case characters to define 5683 token strings is for editorial clarity only. Implementations MUST 5684 accept these strings in a case-insensitive fashion. 5686 (2) In all cases, SP refers to exactly one space. It is NOT 5687 permitted to substitute TAB, insert additional spaces, or 5688 otherwise treat SP as being equivalent to LWSP. 5690 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5692 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5693 addr-host ")" 5695 addr-adl = nstring 5696 ; Holds route from [RFC-5322] obs-route if 5697 ; non-NIL 5699 addr-host = nstring 5700 ; NIL indicates [RFC-5322] group syntax. 5701 ; Otherwise, holds [RFC-5322] domain name 5703 addr-mailbox = nstring 5704 ; NIL indicates end of [RFC-5322] group; if 5705 ; non-NIL and addr-host is NIL, holds 5706 ; [RFC-5322] group name. 5707 ; Otherwise, holds [RFC-5322] local-part 5708 ; after removing [RFC-5322] quoting 5710 addr-name = nstring 5711 ; If non-NIL, holds phrase from [RFC-5322] 5712 ; mailbox after removing [RFC-5322] quoting 5714 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5715 literal 5717 append-uid = uniqueid 5719 astring = 1*ASTRING-CHAR / string 5721 ASTRING-CHAR = ATOM-CHAR / resp-specials 5723 atom = 1*ATOM-CHAR 5725 ATOM-CHAR = 5727 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5728 quoted-specials / resp-specials 5730 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5731 *(CRLF base64) 5733 auth-type = atom 5734 ; Defined by [SASL] 5736 base64 = *(4base64-char) [base64-terminal] 5738 base64-char = ALPHA / DIGIT / "+" / "/" 5739 ; Case-sensitive 5741 base64-terminal = (2base64-char "==") / (3base64-char "=") 5743 body = "(" (body-type-1part / body-type-mpart) ")" 5745 body-extension = nstring / number / 5746 "(" body-extension *(SP body-extension) ")" 5747 ; Future expansion. Client implementations 5748 ; MUST accept body-extension fields. Server 5749 ; implementations MUST NOT generate 5750 ; body-extension fields except as defined by 5751 ; future standard or standards-track 5752 ; revisions of this specification. 5754 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5755 [SP body-fld-loc *(SP body-extension)]]] 5756 ; MUST NOT be returned on non-extensible 5757 ; "BODY" fetch 5759 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5760 [SP body-fld-loc *(SP body-extension)]]] 5761 ; MUST NOT be returned on non-extensible 5762 ; "BODY" fetch 5764 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5765 body-fld-enc SP body-fld-octets 5767 body-fld-desc = nstring 5769 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5771 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5772 "QUOTED-PRINTABLE") DQUOTE) / string 5774 body-fld-id = nstring 5776 body-fld-lang = nstring / "(" string *(SP string) ")" 5778 body-fld-loc = nstring 5780 body-fld-lines = number 5782 body-fld-md5 = nstring 5784 body-fld-octets = number 5786 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5788 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5789 [SP body-ext-1part] 5791 body-type-basic = media-basic SP body-fields 5792 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5794 body-type-mpart = 1*body SP media-subtype 5795 [SP body-ext-mpart] 5796 ; MULTIPART body part 5798 body-type-msg = media-message SP body-fields SP envelope 5799 SP body SP body-fld-lines 5801 body-type-text = media-text SP body-fields SP body-fld-lines 5803 capability = ("AUTH=" auth-type) / atom 5804 ; New capabilities MUST begin with "X" or be 5805 ; registered with IANA in 5806 ; a standards-track, an experimental 5807 ; or an informational RFC. 5809 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5810 *(SP capability) 5811 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5812 ; and LOGINDISABLED capabilities. 5813 ; Servers which offer RFC 1730 compatibility MUST 5814 ; list "IMAP4" as the first capability. 5815 ; Servers which offer RFC 3501 compatibility MUST 5816 ; list "IMAP4rev1" as one of capabilities. 5818 CHAR8 = %x01-ff 5819 ; any OCTET except NUL, %x00 5821 charset = atom / quoted 5823 childinfo-extended-item = "CHILDINFO" SP "(" 5824 list-select-base-opt-quoted 5825 *(SP list-select-base-opt-quoted) ")" 5826 ; Extended data item (mbox-list-extended-item) 5827 ; returned when the RECURSIVEMATCH 5828 ; selection option is specified. 5829 ; Note 1: the CHILDINFO tag can be returned 5830 ; with and without surrounding quotes, as per 5831 ; mbox-list-extended-item-tag production. 5832 ; Note 2: The selection options are always returned 5833 ; quoted, unlike their specification in 5834 ; the extended LIST command. 5836 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5837 ; attributes for CHILDREN return option, at most one 5838 ; possible per LIST response 5840 command = tag SP (command-any / command-auth / command-nonauth / 5841 command-select) CRLF 5842 ; Modal based on state 5844 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / enable / x-command 5845 ; Valid in all states 5847 command-auth = append / create / delete / examine / list / 5848 Namespace-Command / 5849 rename / select / status / subscribe / unsubscribe / 5850 idle 5851 ; Valid only in Authenticated or Selected state 5853 command-nonauth = login / authenticate / "STARTTLS" 5854 ; Valid only when in Not Authenticated state 5856 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 5857 move / fetch / store / search / uid 5858 ; Valid only when in Selected state 5860 continue-req = "+" SP (resp-text / base64) CRLF 5862 copy = "COPY" SP sequence-set SP mailbox 5864 create = "CREATE" SP mailbox 5865 ; Use of INBOX gives a NO error 5867 date = date-text / DQUOTE date-text DQUOTE 5869 date-day = 1*2DIGIT 5870 ; Day of month 5872 date-day-fixed = (SP DIGIT) / 2DIGIT 5873 ; Fixed-format version of date-day 5875 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 5876 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 5878 date-text = date-day "-" date-month "-" date-year 5880 date-year = 4DIGIT 5882 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 5883 SP time SP zone DQUOTE 5885 delete = "DELETE" SP mailbox 5886 ; Use of INBOX gives a NO error 5888 digit-nz = %x31-39 5889 ; 1-9 5891 eitem-standard-tag = atom 5892 ; a tag for extended list data defined in a Standard 5893 ; Track or Experimental RFC. 5895 eitem-vendor-tag = vendor-token "-" atom 5896 ; a vendor-specific tag for extended list data 5898 enable = "ENABLE" 1*(SP capability) 5900 enable-data = "ENABLED" *(SP capability) 5902 envelope = "(" env-date SP env-subject SP env-from SP 5903 env-sender SP env-reply-to SP env-to SP env-cc SP 5904 env-bcc SP env-in-reply-to SP env-message-id ")" 5906 env-bcc = "(" 1*address ")" / nil 5907 env-cc = "(" 1*address ")" / nil 5909 env-date = nstring 5911 env-from = "(" 1*address ")" / nil 5913 env-in-reply-to = nstring 5915 env-message-id = nstring 5917 env-reply-to = "(" 1*address ")" / nil 5919 env-sender = "(" 1*address ")" / nil 5921 env-subject = nstring 5923 env-to = "(" 1*address ")" / nil 5925 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 5926 *(SP search-return-data) 5927 ; ESEARCH response replaces SEARCH response 5928 ; from IMAP4rev1. 5930 examine = "EXAMINE" SP mailbox 5932 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 5933 fetch-att / "(" fetch-att *(SP fetch-att) ")") 5935 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 5936 "RFC822.SIZE" / 5937 "BODY" ["STRUCTURE"] / "UID" / 5938 "BODY" section [partial] / 5939 "BODY.PEEK" section [partial] / 5940 "BINARY" [".PEEK"] section-binary [partial] / 5941 "BINARY.SIZE" section-binary 5943 flag = "\Answered" / "\Flagged" / "\Deleted" / 5944 "\Seen" / "\Draft" / flag-keyword / flag-extension 5945 ; Does not include "\Recent" 5947 flag-extension = "\" atom 5948 ; Future expansion. Client implementations 5949 ; MUST accept flag-extension flags. Server 5950 ; implementations MUST NOT generate 5951 ; flag-extension flags except as defined by 5952 ; future standard or standards-track 5953 ; revisions of this specification. 5954 ; "\Recent" was defined in RFC 3501 5955 ; and is now deprecated. 5957 flag-fetch = flag 5959 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 5960 "$NotJunk" / "$Phishing" / atom 5962 flag-list = "(" [flag *(SP flag)] ")" 5964 flag-perm = flag / "\*" 5966 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 5968 header-fld-name = astring 5970 header-list = "(" header-fld-name *(SP header-fld-name) ")" 5972 idle = "IDLE" CRLF "DONE" 5974 initial-resp = (base64 / "=") 5975 ; "initial response" defined in 5976 ; Section 5.1 of [RFC4422] 5978 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 5979 [SP list-return-opts] 5981 list-mailbox = 1*list-char / string 5983 list-char = ATOM-CHAR / list-wildcards / resp-specials 5985 list-return-opts = "RETURN" SP 5986 "(" [return-option *(SP return-option)] ")" 5987 ; list return options, e.g., CHILDREN 5989 list-select-base-opt = "SUBSCRIBED" / option-extension 5990 ; options that can be used by themselves 5992 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 5994 list-select-independent-opt = "REMOTE" / option-extension 5995 ; options that do not syntactically interact with 5996 ; other options 5998 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 5999 ; options that require a list-select-base-opt 6000 ; to also be present 6002 list-select-opt = list-select-base-opt / list-select-independent-opt 6003 / list-select-mod-opt 6004 ; An option registration template is described in 6005 ; Section 9.3 of this document. 6007 list-select-opts = "(" [ 6008 (*(list-select-opt SP) list-select-base-opt 6009 *(SP list-select-opt)) 6010 / (list-select-independent-opt 6011 *(SP list-select-independent-opt)) 6012 ] ")" 6013 ; Any number of options may be in any order. 6014 ; If a list-select-mod-opt appears, then a 6015 ; list-select-base-opt must also appear. 6016 ; This allows these: 6017 ; () 6018 ; (REMOTE) 6019 ; (SUBSCRIBED) 6020 ; (SUBSCRIBED REMOTE) 6021 ; (SUBSCRIBED RECURSIVEMATCH) 6022 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6023 ; But does NOT allow these: 6024 ; (RECURSIVEMATCH) 6025 ; (REMOTE RECURSIVEMATCH) 6027 list-wildcards = "%" / "*" 6029 literal = "{" number ["+"] "}" CRLF *CHAR8 6030 ; represents the number of CHAR8s. 6031 ; A non-synchronizing literal is distinguished from 6032 ; a synchronizing literal by presence of the "+" 6033 ; before the closing "}". 6034 ; Non synchronizing literals are not allowed when 6035 ; sent from server to the client. 6037 literal8 = "~{" number "}" CRLF *OCTET 6038 ; represents the number of OCTETs 6039 ; in the response string. 6041 login = "LOGIN" SP userid SP password 6043 mailbox = "INBOX" / astring 6044 ; INBOX is case-insensitive. All case variants of 6045 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6046 ; not as an astring. An astring which consists of 6047 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6048 ; is considered to be INBOX and not an astring. 6049 ; Refer to section 5.1 for further 6050 ; semantic details of mailbox names. 6052 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6053 esearch-response / 6054 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6055 number SP "EXISTS" / Namespace-Response 6057 mailbox-list = "(" [mbx-list-flags] ")" SP 6058 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6059 [SP mbox-list-extended] 6060 ; This is the list information pointed to by the ABNF 6061 ; item "mailbox-data", which is defined in [IMAP4] 6063 mbox-list-extended = "(" [mbox-list-extended-item 6064 *(SP mbox-list-extended-item)] ")" 6066 mbox-list-extended-item = mbox-list-extended-item-tag SP 6067 tagged-ext-val 6069 mbox-list-extended-item-tag = astring 6070 ; The content MUST conform to either "eitem-vendor-tag" 6071 ; or "eitem-standard-tag" ABNF productions. 6073 mbox-or-pat = list-mailbox / patterns 6075 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6076 *(SP mbx-list-oflag) / 6077 mbx-list-oflag *(SP mbx-list-oflag) 6079 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6080 "\Subscribed" / "\Remote" / flag-extension 6081 ; Other flags; multiple possible per LIST response 6083 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6084 ; Selectability flags; only one per LIST response 6086 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6087 "MESSAGE" / "VIDEO" / "FONT") DQUOTE) / string) SP 6088 media-subtype 6089 ; Defined in [MIME-IMT]. 6090 ; FONT defined in RFC YYYY. 6092 media-message = DQUOTE "MESSAGE" DQUOTE SP 6093 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6094 ; Defined in [MIME-IMT] 6096 media-subtype = string 6097 ; Defined in [MIME-IMT] 6099 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6100 ; Defined in [MIME-IMT] 6102 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6104 move = "MOVE" SP sequence-set SP mailbox 6106 msg-att = "(" (msg-att-dynamic / msg-att-static) 6107 *(SP (msg-att-dynamic / msg-att-static)) ")" 6109 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6110 ; MAY change for a message 6112 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6113 "RFC822.SIZE" SP number / 6114 "BODY" ["STRUCTURE"] SP body / 6115 "BODY" section ["<" number ">"] SP nstring / 6116 "BINARY" section-binary SP (nstring / literal8) / 6117 "BINARY.SIZE" section-binary SP number / 6118 "UID" SP uniqueid 6119 ; MUST NOT change for a message 6121 Namespace = nil / "(" 1*Namespace-Descr ")" 6123 Namespace-Command = "NAMESPACE" 6125 Namespace-Descr = "(" string SP 6126 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6127 [Namespace-Response-Extensions] ")" 6129 Namespace-Response-Extensions = *(Namespace-Response-Extension) 6131 Namespace-Response-Extension = SP string SP 6132 "(" string *(SP string) ")" 6134 Namespace-Response = "NAMESPACE" SP Namespace 6135 SP Namespace SP Namespace 6136 ; The first Namespace is the Personal Namespace(s). 6137 ; The second Namespace is the Other Users' 6138 ; Namespace(s). 6139 ; The third Namespace is the Shared Namespace(s). 6141 nil = "NIL" 6143 nstring = string / nil 6145 number = 1*DIGIT 6146 ; Unsigned 32-bit integer 6147 ; (0 <= n < 4,294,967,296) 6149 number64 = 1*DIGIT 6150 ; Unsigned 63-bit integer 6151 ; (0 <= n <= 9,223,372,036,854,775,807) 6153 nz-number = digit-nz *DIGIT 6154 ; Non-zero unsigned 32-bit integer 6155 ; (0 < n < 4,294,967,296) 6157 option-extension = (option-standard-tag / option-vendor-tag) 6158 [SP option-value] 6160 option-standard-tag = atom 6161 ; an option defined in a Standards Track or 6162 ; Experimental RFC 6164 option-val-comp = astring / 6165 option-val-comp *(SP option-val-comp) / 6166 "(" option-val-comp ")" 6168 option-value = "(" option-val-comp ")" 6170 option-vendor-tag = vendor-token "-" atom 6171 ; a vendor-specific option, non-standard 6173 partial-range = number ["." nz-number] 6174 ; Copied from RFC 5092 (IMAP URL) 6176 partial = "<" number "." nz-number ">" 6177 ; Partial FETCH request. 0-based offset of 6178 ; the first octet, followed by the number of octets 6179 ; in the fragment. 6181 password = astring 6183 patterns = "(" list-mailbox ")" 6184 ; [RFC5258] supports multiple patterns, 6185 ; but this document only requires one 6186 ; to be supported. 6187 ; If the server is also implementing 6188 ; [RFC5258], "patterns" syntax from that 6189 ; document must be followed. 6191 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6193 QUOTED-CHAR = / 6194 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6196 quoted-specials = DQUOTE / "\" 6198 rename = "RENAME" SP mailbox SP mailbox 6199 ; Use of INBOX as a destination gives a NO error 6201 response = *(continue-req / response-data) response-done 6203 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6204 mailbox-data / message-data / capability-data / 6205 enable-data) CRLF 6207 response-done = response-tagged / response-fatal 6209 response-fatal = "*" SP resp-cond-bye CRLF 6210 ; Server closes connection immediately 6212 response-tagged = tag SP resp-cond-state CRLF 6214 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6216 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6218 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6219 ; Authentication condition 6221 resp-cond-bye = "BYE" SP resp-text 6223 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6224 ; Status condition 6226 resp-specials = "]" 6228 resp-text = ["[" resp-text-code "]" SP] [text] 6230 resp-text-code = "ALERT" / 6231 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6232 capability-data / "PARSE" / 6233 "PERMANENTFLAGS" SP "(" 6234 [flag-perm *(SP flag-perm)] ")" / 6235 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6236 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6237 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6238 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6239 "AUTHORIZATIONFAILED" / "EXPIRED" / 6240 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6241 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6242 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6243 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6244 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6245 "CLOSED" / 6246 "UNKNOWN-CTE" / 6247 atom [SP 1*] 6249 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6250 option-extension 6252 search = "SEARCH" [search-return-opts] 6253 SP search-program 6255 search-correlator = SP "(" "TAG" SP tag-string ")" 6257 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6258 "BEFORE" SP date / "BODY" SP astring / 6259 "CC" SP astring / "DELETED" / "FLAGGED" / 6260 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6261 "ON" SP date / "SEEN" / 6262 "SINCE" SP date / "SUBJECT" SP astring / 6263 "TEXT" SP astring / "TO" SP astring / 6264 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6265 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6266 ; Above this line were in [IMAP2] 6267 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6268 "LARGER" SP number / "NOT" SP search-key / 6269 "OR" SP search-key SP search-key / 6270 "SENTBEFORE" SP date / "SENTON" SP date / 6271 "SENTSINCE" SP date / "SMALLER" SP number / 6272 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6273 "(" search-key *(SP search-key) ")" 6275 search-modifier-name = tagged-ext-label 6277 search-mod-params = tagged-ext-val 6278 ; This non-terminal shows recommended syntax 6279 ; for future extensions. 6281 search-program = ["CHARSET" SP charset SP] 6282 search-key *(SP search-key) 6283 ; CHARSET argument to SEARCH MUST be 6284 ; registered with IANA. 6286 search-ret-data-ext = search-modifier-name SP search-return-value 6287 ; Note that not every SEARCH return option 6288 ; is required to have the corresponding 6289 ; ESEARCH return data. 6291 search-return-data = "MIN" SP nz-number / 6292 "MAX" SP nz-number / 6293 "ALL" SP sequence-set / 6294 "COUNT" SP number / 6295 search-ret-data-ext 6296 ; All return data items conform to 6297 ; search-ret-data-ext syntax. 6298 ; Note that "$" marker is not allowed 6299 ; after the ALL return data item. 6301 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6302 *(SP search-return-opt)] ")" 6304 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6305 "SAVE" / 6306 search-ret-opt-ext 6307 ; conforms to generic search-ret-opt-ext 6308 ; syntax 6310 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6312 search-return-value = tagged-ext-val 6313 ; Data for the returned search option. 6314 ; A single "nz-number"/"number"/"number64" value 6315 ; can be returned as an atom (i.e., without 6316 ; quoting). A sequence-set can be returned 6317 ; as an atom as well. 6319 section = "[" [section-spec] "]" 6321 section-binary = "[" [section-part] "]" 6323 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6324 "TEXT" 6325 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6327 section-part = nz-number *("." nz-number) 6328 ; body part reference. 6329 ; Allows for accessing nested body parts. 6331 section-spec = section-msgtext / (section-part ["." section-text]) 6333 section-text = section-msgtext / "MIME" 6334 ; text other than actual body part (headers, etc.) 6336 select = "SELECT" SP mailbox 6338 seq-number = nz-number / "*" 6339 ; message sequence number (COPY, FETCH, STORE 6340 ; commands) or unique identifier (UID COPY, 6341 ; UID FETCH, UID STORE commands). 6342 ; * represents the largest number in use. In 6343 ; the case of message sequence numbers, it is 6344 ; the number of messages in a non-empty mailbox. 6345 ; In the case of unique identifiers, it is the 6346 ; unique identifier of the last message in the 6347 ; mailbox or, if the mailbox is empty, the 6348 ; mailbox's current UIDNEXT value. 6349 ; The server should respond with a tagged BAD 6350 ; response to a command that uses a message 6351 ; sequence number greater than the number of 6352 ; messages in the selected mailbox. This 6353 ; includes "*" if the selected mailbox is empty. 6355 seq-range = seq-number ":" seq-number 6356 ; two seq-number values and all values between 6357 ; these two regardless of order. 6358 ; Example: 2:4 and 4:2 are equivalent and indicate 6359 ; values 2, 3, and 4. 6360 ; Example: a unique identifier sequence range of 6361 ; 3291:* includes the UID of the last message in 6362 ; the mailbox, even if that value is less than 3291. 6364 sequence-set = (seq-number / seq-range) ["," sequence-set] 6365 ; set of seq-number values, regardless of order. 6366 ; Servers MAY coalesce overlaps and/or execute the 6367 ; sequence in any order. 6368 ; Example: a message sequence number set of 6369 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6370 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6371 ; Example: a message sequence number set of *:4,5:7 6372 ; for a mailbox with 10 messages is equivalent to 6373 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6374 ; overlap coalesced to be 4,5,6,7,8,9,10. 6376 sequence-set =/ seq-last-command 6377 ; Allow for "result of the last command" indicator. 6379 seq-last-command = "$" 6381 status = "STATUS" SP mailbox SP 6382 "(" status-att *(SP status-att) ")" 6384 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6385 "UNSEEN" / "DELETED" / "SIZE" 6387 status-att-val = ("MESSAGES" SP number) / 6388 ("UIDNEXT" SP nz-number) / 6389 ("UIDVALIDITY" SP nz-number) / 6390 ("UNSEEN" SP number) / 6391 ("DELETED" SP number) / 6392 ("SIZE" SP number64) 6393 ; Extensions to the STATUS responses 6394 ; should extend this production. 6395 ; Extensions should use the generic 6396 ; syntax defined by tagged-ext. 6398 status-att-list = status-att-val *(SP status-att-val) 6400 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6401 ; This ABNF production complies with 6402 ; syntax. 6404 store = "STORE" SP sequence-set SP store-att-flags 6406 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6407 (flag-list / (flag *(SP flag))) 6409 string = quoted / literal 6411 subscribe = "SUBSCRIBE" SP mailbox 6413 tag = 1* 6415 tagged-ext-label = tagged-label-fchar *tagged-label-char 6416 ;; Is a valid RFC 3501 "atom". 6418 tagged-label-fchar = ALPHA / "-" / "_" / "." 6420 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6422 tagged-ext-comp = astring / 6423 tagged-ext-comp *(SP tagged-ext-comp) / 6424 "(" tagged-ext-comp ")" 6425 ;; Extensions that follow this general 6426 ;; syntax should use nstring instead of 6427 ;; astring when appropriate in the context 6428 ;; of the extension. 6429 ;; Note that a message set or a "number" 6430 ;; can always be represented as an "atom". 6431 ;; An URL should be represented as 6432 ;; a "quoted" string. 6434 tagged-ext-simple = sequence-set / number / number64 6435 tagged-ext-val = tagged-ext-simple / 6436 "(" [tagged-ext-comp] ")" 6438 text = 1*TEXT-CHAR 6440 TEXT-CHAR = 6442 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6443 ; Hours minutes seconds 6445 uid = "UID" SP 6446 (copy / move / fetch / search / store / uid-expunge) 6447 ; Unique identifiers used instead of message 6448 ; sequence numbers 6450 uid-expunge = "EXPUNGE" SP sequence-set 6451 ; Unique identifiers used instead of message 6452 ; sequence numbers 6454 uid-set = (uniqueid / uid-range) *("," uid-set) 6456 uid-range = (uniqueid ":" uniqueid) 6457 ; two uniqueid values and all values 6458 ; between these two regards of order. 6459 ; Example: 2:4 and 4:2 are equivalent. 6461 uniqueid = nz-number 6462 ; Strictly ascending 6464 unsubscribe = "UNSUBSCRIBE" SP mailbox 6466 userid = astring 6468 UTF8-2 = 6470 UTF8-3 = 6472 UTF8-4 = 6474 x-command = "X" atom 6476 zone = ("+" / "-") 4DIGIT 6477 ; Signed four-digit value of hhmm representing 6478 ; hours and minutes east of Greenwich (that is, 6479 ; the amount that the given time differs from 6480 ; Universal Time). Subtracting the timezone 6481 ; from the given time will give the UT form. 6482 ; The Universal Time zone is "+0000". 6484 10. Author's Note 6486 This document is a revision or rewrite of earlier documents, and 6487 supercedes the protocol specification in those documents: RFC 2060, 6488 RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and RFC 1064. 6490 11. Security Considerations 6492 IMAP4rev2 protocol transactions, including electronic mail data, are 6493 sent in the clear over the network unless protection from snooping is 6494 negotiated. This can be accomplished either by the use of IMAPS 6495 service, STARTTLS command, negotiated privacy protection in the 6496 AUTHENTICATE command, or some other protection mechanism. 6498 11.1. STARTTLS Security Considerations 6500 IMAP client and server implementations MUST comply with relevant TLS 6501 recommendations from [RFC8314]. Additionally, when using TLS 1.2, 6502 IMAP implementations MUST implement 6503 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6504 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS] cipher suite. This 6505 is important as it assures that any two compliant implementations can 6506 be configured to interoperate. Other TLS cipher suites recommended 6507 in RFC 7525 are RECOMMENDED: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6508 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6509 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6510 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6512 During the [TLS] negotiation, the client MUST check its understanding 6513 of the server hostname against the server's identity as presented in 6514 the server Certificate message, in order to prevent man-in-the-middle 6515 attacks. This procedure is described in [RFC7817]. 6517 Both the client and server MUST check the result of the STARTTLS 6518 command and subsequent [TLS] negotiation to see whether acceptable 6519 authentication and/or privacy was achieved. 6521 11.2. COPYUID and APPENDUID response codes 6523 The COPYUID and APPENDUID response codes return information about the 6524 mailbox, which may be considered sensitive if the mailbox has 6525 permissions set that permit the client to COPY or APPEND to the 6526 mailbox, but not SELECT or EXAMINE it. 6528 Consequently, these response codes SHOULD NOT be issued if the client 6529 does not have access to SELECT or EXAMINE the mailbox. 6531 11.3. LIST command and Other Users' namespace 6533 In response to a LIST command containing an argument of the Other 6534 Users' Namespace prefix, a server SHOULD NOT list users that have not 6535 granted list access to their personal mailboxes to the currently 6536 authenticated user. Providing such a list, could compromise security 6537 by potentially disclosing confidential information of who is located 6538 on the server, or providing a starting point of a list of user 6539 accounts to attack. 6541 11.4. Other Security Considerations 6543 A server error message for an AUTHENTICATE command which fails due to 6544 invalid credentials SHOULD NOT detail why the credentials are 6545 invalid. 6547 Use of the LOGIN command sends passwords in the clear. This can be 6548 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6549 that does not use plaintext passwords, by first negotiating 6550 encryption via STARTTLS or some other protection mechanism. 6552 A server implementation MUST implement a configuration that, at the 6553 time of authentication, requires: 6554 (1) The STARTTLS command has been negotiated. 6555 OR 6556 (2) Some other mechanism that protects the session from password 6557 snooping has been provided. 6558 OR 6559 (3) The following measures are in place: 6560 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6561 (such as PLAIN) using plaintext passwords are NOT advertised in the 6562 CAPABILITY list. 6563 AND 6564 (b) The LOGIN command returns an error even if the password is 6565 correct. 6566 AND 6567 (c) The AUTHENTICATE command returns an error with all [SASL] 6568 mechanisms that use plaintext passwords, even if the password is 6569 correct. 6571 A server error message for a failing LOGIN command SHOULD NOT specify 6572 that the user name, as opposed to the password, is invalid. 6574 A server SHOULD have mechanisms in place to limit or delay failed 6575 AUTHENTICATE/LOGIN attempts. 6577 Additional security considerations are discussed in the section 6578 discussing the AUTHENTICATE and LOGIN commands. 6580 12. IANA Considerations 6582 IANA is requested to update "Service Names and Transport Protocol 6583 Port Numbers" registry as follows: 6585 1. Registration for TCP "imap" port 143 should be updated to point 6586 to this document and RFC 3501. 6588 2. Registration for TCP "imaps" port 993 should be updated to point 6589 to this document, RFC 8314 and RFC 3501. 6591 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6592 in the registry. 6594 Additional IANA actions are specified in subsection of this section. 6596 12.1. Updates to IMAP4 Capabilities registry 6598 IMAP4 capabilities are registered by publishing a standards track or 6599 IESG approved informational or experimental RFC. The registry is 6600 currently located at: https://www.iana.org/assignments/ 6601 imap4-capabilities 6603 As this specification revises the AUTH= prefix, STARTTLS and 6604 LOGINDISABLED extensions previously defined in [IMAP-TLS], IANA is 6605 requested to update registry entries for these 3 extensions to point 6606 to this document. 6608 12.2. GSSAPI/SASL service name 6610 GSSAPI/Kerberos/SASL service names are registered by publishing a 6611 standards track or IESG approved experimental RFC. The registry is 6612 currently located at: https://www.iana.org/assignments/gssapi- 6613 service-names 6615 IANA is requested to update the "imap" service name previously 6616 registered in RFC 3501, to point to this document. 6618 13. References 6620 13.1. Normative References 6622 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6623 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6624 . 6626 [ANONYMOUS] 6627 Zeilenga, K., "Anonymous Simple Authentication and 6628 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6629 . 6631 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6632 Procedures", BCP 19, RFC 2978, October 2000, 6633 . 6635 [SCRAM-SHA-256] 6636 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6637 Authentication and Security Layer (SASL) Mechanisms", 6638 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6639 . 6641 [DISPOSITION] 6642 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6643 Presentation Information in Internet Messages: The 6644 Content-Disposition Header Field", RFC 2183, August 1997, 6645 . 6647 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6648 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6649 . 6651 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6652 Requirement Levels", BCP 14, RFC 2119, 6653 DOI 10.17487/RFC2119, March 1997, 6654 . 6656 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6657 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6658 May 2017, . 6660 [LANGUAGE-TAGS] 6661 Alvestrand, H., "Content Language Headers", RFC 3282, May 6662 2002, . 6664 [LOCATION] 6665 Palme, J., Hopmann, A., and N. Shelness, "MIME 6666 Encapsulation of Aggregate Documents, such as HTML 6667 (MHTML)", RFC 2557, March 1999, 6668 . 6670 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6671 RFC 1864, October 1995, 6672 . 6674 [MIME-HDRS] 6675 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6676 Part Three: Message Header Extensions for Non-ASCII Text", 6677 RFC 2047, November 1996, 6678 . 6680 [MIME-IMB] 6681 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6682 Extensions (MIME) Part One: Format of Internet Message 6683 Bodies", RFC 2045, November 1996, 6684 . 6686 [MIME-IMT] 6687 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6688 Extensions (MIME) Part Two: Media Types", RFC 2046, 6689 November 1996, . 6691 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6692 Word Extensions: Character Sets, Languages, and 6693 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6694 1997, . 6696 [RFC-5322] 6697 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6698 October 2008, . 6700 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6701 Authentication and Security Layer (SASL)", RFC 4422, June 6702 2006, . 6704 [TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security 6705 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6706 . 6708 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6709 Transformation Format of Unicode", RFC 2152, May 1997, 6710 . 6712 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6713 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6714 2003, . 6716 [MULTIAPPEND] 6717 Crispin, M., "Internet Message Access Protocol (IMAP) - 6718 MULTIAPPEND Extension", RFC 3502, March 2003, 6719 . 6721 [NET-UNICODE] 6722 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6723 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6724 . 6726 [I18N-HDRS] 6727 Yang, A., Steele, S., and N. Freed, "Internationalized 6728 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6729 2012, . 6731 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6732 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6733 . 6735 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6736 Server Identity Check Procedure for Email-Related 6737 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6738 . 6740 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6741 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6742 February 2017, . 6744 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6745 Use of Transport Layer Security (TLS) for Email Submission 6746 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6747 . 6749 [IMAP-IMPLEMENTATION] 6750 Leiba, B., "IMAP4 Implementation Recommendations", 6751 RFC 2683, September 1999, 6752 . 6754 [IMAP-MULTIACCESS] 6755 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6756 RFC 2180, July 1997, 6757 . 6759 13.2. Informative References (related protocols) 6761 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 6762 profile for Internet Message Access Protocol (IMAP)", 6763 RFC 3503, DOI 10.17487/RFC3503, March 2003, 6764 . 6766 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6767 Protocol - SORT and THREAD Extensions", RFC 5256, 6768 DOI 10.17487/RFC5256, June 2008, 6769 . 6771 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6772 Protocol version 4 - LIST Command Extensions", RFC 5258, 6773 DOI 10.17487/RFC5258, June 2008, 6774 . 6776 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6777 DOI 10.17487/RFC2193, September 1997, 6778 . 6780 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 6781 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 6782 DOI 10.17487/RFC3348, July 2002, 6783 . 6785 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 6786 RFC 7888, DOI 10.17487/RFC7888, May 2016, 6787 . 6789 [IMAP-DISC] 6790 Melnikov, A., Ed., "Synchronization Operations for 6791 Disconnected IMAP4 Clients", RFC 4549, June 2006, 6792 . 6794 [IMAP-I18N] 6795 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 6796 Message Access Protocol Internationalization", RFC 5255, 6797 DOI 10.17487/RFC5255, June 2008, 6798 . 6800 [IMAP-MODEL] 6801 Crispin, M., "Distributed Electronic Mail Models in 6802 IMAP4", RFC 1733, December 1994, 6803 . 6805 [IMAP-UTF-8] 6806 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 6807 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 6808 2013, . 6810 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 6811 October 2008, . 6813 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 6814 DOI 10.17487/RFC3516, April 2003, 6815 . 6817 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 6818 RFC 4314, December 2005, 6819 . 6821 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 6822 1997, . 6824 [IMAP-URL] 6825 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 6826 RFC 5092, DOI 10.17487/RFC5092, November 2007, 6827 . 6829 [IMAP-KEYWORDS-REG] 6830 IANA, "IMAP and JMAP Keywords", December 2009, 6831 . 6834 [IMAP-MAILBOX-NAME-ATTRS-REG] 6835 IANA, "IMAP Mailbox Name Attributes", June 2018, 6836 . 6839 [CHARSET-REG] 6840 IANA, "Character Set Registrations", May 2015, 6841 . 6844 13.3. Informative References (historical aspects of IMAP and related 6845 protocols) 6847 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 6848 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 6849 . 6851 [IMAP-COMPAT] 6852 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 6853 RFC 2061, December 1996, 6854 . 6856 [IMAP-HISTORICAL] 6857 Crispin, M., "IMAP4 Compatibility with IMAP2 and 6858 IMAP2bis", RFC 1732, December 1994, 6859 . 6861 [IMAP-OBSOLETE] 6862 Crispin, M., "Internet Message Access Protocol - Obsolete 6863 Syntax", RFC 2062, December 1996, 6864 . 6866 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 6867 2", RFC 1176, August 1990, 6868 . 6870 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 6871 TEXT MESSAGES", STD 11, RFC 822, August 1982, 6872 . 6874 [IMAP-TLS] 6875 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 6876 RFC 2595, June 1999, 6877 . 6879 Appendix A. Backward compatibility with IMAP4rev1 6881 An implementation that wants to remain compatible with IMAP4rev1 can 6882 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 6883 response code. While some IMAP4rev1 responses were removed in 6884 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 6886 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 6887 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 6889 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 6890 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 6891 Consider implementation of mechanisms described or referenced in 6892 [IMAP-UTF-8] to achieve this goal. 6894 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 6895 intending to be compatible with IMAP4rev1 servers MUST be compatible 6896 with the international mailbox naming convention described in the 6897 following subsection. 6899 A.1. Mailbox International Naming Convention for compatibility with 6900 IMAP4rev1 6902 Support for the Mailbox International Naming Convention described in 6903 this section is not required for IMAP4rev2-only clients and servers. 6905 By convention, international mailbox names in IMAP4rev1 are specified 6906 using a modified version of the UTF-7 encoding described in [UTF-7]. 6907 Modified UTF-7 may also be usable in servers that implement an 6908 earlier version of this protocol. 6910 In modified UTF-7, printable US-ASCII characters, except for "&", 6911 represent themselves; that is, characters with octet values 0x20-0x25 6912 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 6913 octet sequence "&-". 6915 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 6916 represented in modified BASE64, with a further modification from 6917 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 6918 used to represent any printing US-ASCII character which can represent 6919 itself. Only characters inside the modified BASE64 alphabet are 6920 permitted in modified BASE64 text. 6922 "&" is used to shift to modified BASE64 and "-" to shift back to US- 6923 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 6924 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 6925 "&") are not permitted. However, all names start in US-ASCII, and 6926 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 6927 ISO-10646 character MUST end with a "-"). 6929 The purpose of these modifications is to correct the following 6930 problems with UTF-7: 6932 1. UTF-7 uses the "+" character for shifting; this conflicts with 6933 the common use of "+" in mailbox names, in particular USENET 6934 newsgroup names. 6936 2. UTF-7's encoding is BASE64 which uses the "/" character; this 6937 conflicts with the use of "/" as a popular hierarchy delimiter. 6939 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 6940 the use of "\" as a popular hierarchy delimiter. 6942 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 6943 the use of "~" in some servers as a home directory indicator. 6945 5. UTF-7 permits multiple alternate forms to represent the same 6946 string; in particular, printable US-ASCII characters can be 6947 represented in encoded form. 6949 Although modified UTF-7 is a convention, it establishes certain 6950 requirements on server handling of any mailbox name with an embedded 6951 "&" character. In particular, server implementations MUST preserve 6952 the exact form of the modified BASE64 portion of a modified UTF-7 6953 name and treat that text as case-sensitive, even if names are 6954 otherwise case-insensitive or case-folded. 6956 Server implementations SHOULD verify that any mailbox name with an 6957 embedded "&" character, used as an argument to CREATE, is: in the 6958 correctly modified UTF-7 syntax, has no superfluous shifts, and has 6959 no encoding in modified BASE64 of any printing US-ASCII character 6960 which can represent itself. However, client implementations MUST NOT 6961 depend upon the server doing this, and SHOULD NOT attempt to create a 6962 mailbox name with an embedded "&" character unless it complies with 6963 the modified UTF-7 syntax. 6965 Server implementations which export a mail store that does not follow 6966 the modified UTF-7 convention MUST convert to modified UTF-7 any 6967 mailbox name that contains either non-ASCII characters or the "&" 6968 character. 6970 For example, here is a mailbox name which mixes English, Chinese, 6971 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 6973 For example, the string "&Jjo!" is not a valid mailbox name 6974 because it does not contain a shift to US-ASCII before the "!". 6975 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 6976 not permitted because it contains a superfluous shift. The 6977 correct form is "&U,BTF2XlZyyKng-". 6979 Appendix B. Backward compatibility with BINARY extension 6981 IMAP4rev2 is incorporates subset of functionality provided by the 6982 BINARY extension [RFC3516], in particular it includes additional 6983 FETCH items (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions 6984 to the APPEND command. IMAP4rev2 implementations that supports full 6985 RFC 3516 functionality need to also advertise the BINARY token in the 6986 CAPABILITY response. 6988 Appendix C. Backward compatibility with LIST-EXTENDED extension 6990 IMAP4rev2 is incorporates most of functionality provided by the LIST- 6991 EXTENDED extension [RFC5258]. In particular, multiple mailbox 6992 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 6993 capability is also advertised in CAPABILITY response/response code. 6995 Appendix D. Changes from RFC 3501 / IMAP4rev1 6997 The following is the plan for remaining changes. The plan might 6998 change over time. 7000 1. Revise IANA registration of IMAP extensions and give advice on 7001 use of "X-" convention. 7003 2. Allow word-based searching (as per Chris Newman)? Need to 7004 discuss header field search, where exact/substring match is still 7005 required for interoperability. 7007 3. Add a section on other recommended extensions? 7009 The following changes were already done: 7011 1. Fold in the following extensions/RFC: RFC 5530 (IMAP Response 7012 Codes), UIDPLUS, ENABLE, ESEARCH, SPECIAL-USE (list of new 7013 mailbox attributes), LITERAL-, NAMESPACE, SASL-IR, LIST-STATUS, 7014 SEARCHRES, IDLE, MOVE. 7016 2. Add CLOSED response code (from CONDSTORE). 7018 3. Add support for $Phishing, $Junk, $NonJunk, $MDNSent and 7019 $Forwarded IMAP keywords. Add more examples showing their use? 7021 4. Require all unsolicited FETCH updates to include UID. 7023 5. Update recommendations on TLS ciphers to match UTA WG work (as 7024 per RFC 8314, RFC 7525 and RFC 7817). 7026 6. Fold in the following extensions/RFC: Base LIST-EXTENDED syntax 7027 plus deprecate LSUB (replace it with LIST \Subscribed) minus the 7028 requirement to support multiple list patterns, BINARY (only the 7029 FETCH changes on leaf body part and make APPEND related ones 7030 optional. See the mailing list discussion). 7032 7. Add STATUS SIZE (total mailbox size). Add STATUS DELETED (number 7033 of messages with \Deleted flag set). 7035 8. Drop UTF-7, all mailboxes are always in UTF-8. 7037 The following changes since RFC 3501 were done so far: 7039 1. Folded in IMAP UNSELECT (RFC 3691), UIDPLUS (RFC 4315), ESEARCH 7040 (RFC 4731), SEARCHRES (RFC 5182), ENABLE (RFC 5161), IDLE (RFC 7041 2177), SASL-IR (RFC 4959), LIST-STATUS (RFC 5819) and MOVE (RFC 7042 6851) extensions. Also folded RFC 5530 and FETCH side of the 7043 BINARY extension (RFC 3516). 7045 2. Clarified that server should decode parameter value 7046 continuations as described in [RFC2231]. This requirement was 7047 hidden in RFC 2231 itself. 7049 3. SEARCH command now requires to return ESEARCH response (SEARCH 7050 response is now deprecated). 7052 4. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7053 mailbox is already selected now require for the CLOSED response 7054 code to be returned. 7056 5. Updated to use modern TLS-related recommendations as per RFC 7057 8314, RFC 7817, RFC 7525. 7059 6. For future extensibility extended ABNF for tagged-ext-simple to 7060 allow for bare number64. 7062 7. Added SHOULD level requirement on IMAP servers to support 7063 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7065 8. Added STATUS SIZE and STATUS DELETED. 7067 9. Mailbox names and message headers now allow for UTF-8. Support 7068 for Modified UTF-7 in mailbox names is not required, unless 7069 compatibility with IMAP4rev1 is desired. 7071 10. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7073 11. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7074 SEARCH NEW items are now deprecated. 7076 12. Clarified that the server doesn't need to send a new 7077 PERMANENTFLAGS response code when a new keyword was successfully 7078 added and the server advertised \* earlier for the same mailbox. 7080 13. Removed the CHECK command. Clients should use NOOP instead. 7082 14. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7083 deprecated. Clients should use the corresponding BODY[] 7084 variants instead. 7086 15. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7087 MD5 was deprecated. 7089 16. LSUB command was deprecated. Clients should use LIST 7090 (SUBSCRIBED) instead. 7092 17. resp-text ABNF non terminal was updated to allow for empty text. 7094 18. IDLE command can now return updates not related to the currently 7095 selected mailbox state. 7097 19. All unsolicited FETCH updates are required to include UID. 7099 20. Clarified that client implementations MUST ignore response codes 7100 that they do not recognize. (Change from a SHOULD to a MUST.) 7102 Appendix E. Acknowledgement 7104 Earlier versions of this document were edited by Mark Crispin. 7105 Sadly, he is no longer available to help with this work. Editors of 7106 this revisions are hoping that Mark would have approved. 7108 Chris Newman has contributed text on I18N and use of UTF-8 in 7109 messages and mailbox names. 7111 Thank you to Tony Hansen for helping with the index generation. 7112 Thank you to Timo Sirainen, Bron Gondwana and Arnt Gulbrandsen for 7113 extensive feedback. 7115 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7116 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7117 Gulbrandsen), RFC 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo 7118 Sirainen), RFC 6154 (by Jamie Nicolson) so work done by authors/ 7119 editors of these documents is appreciated. Note that editors of this 7120 document were redacted from the above list. 7122 Index 7124 $ 7125 $Forwarded (predefined flag) 12 7126 $Junk (predefined flag) 12 7127 $MDNSent (predefined flag) 12 7128 $NotJunk (predefined flag) 12 7129 $Phishing (predefined flag) 12 7131 + 7132 +FLAGS 90 7133 +FLAGS.SILENT 90 7135 - 7136 -FLAGS 90 7137 -FLAGS.SILENT 90 7139 A 7140 ALERT (response code) 97 7141 ALL (fetch item) 86 7142 ALL (search key) 76 7143 ALL (search result option) 74 7144 ALREADYEXISTS (response code) 97 7145 ANSWERED (search key) 76 7146 APPEND (command) 66 7147 APPENDUID (response code) 97 7148 AUTHENTICATE (command) 29 7149 AUTHENTICATIONFAILED (response code) 98 7150 AUTHORIZATIONFAILED (response code) 98 7152 B 7153 BAD (response) 106 7154 BADCHARSET (response code) 99 7155 BCC (search key) 76 7156 BEFORE (search key) 76 7157 BINARY.PEEK[]<> (fetch item) 86 7158 BINARY.SIZE[] (fetch item) 86 7159 BINARY.SIZE[] (fetch result) 116 7160 BINARY[]<> (fetch result) 115 7161 BINARY[]<> (fetch item) 86 7162 BODY (fetch item) 87 7163 BODY (fetch result) 116 7164 BODY (search key) 76 7165 BODY.PEEK[
]<> (fetch item) 89 7166 BODYSTRUCTURE (fetch item) 89 7167 BODYSTRUCTURE (fetch result) 117 7168 BODY[
]<> (fetch result) 116 7169 BODY[
]<> (fetch item) 87 7170 BYE (response) 106 7171 Body Structure (message attribute) 14 7173 C 7174 CANNOT (response code) 99 7175 CAPABILITY (command) 25 7176 CAPABILITY (response code) 99 7177 CAPABILITY (response) 107 7178 CC (search key) 76 7179 CLIENTBUG (response code) 99 7180 CLOSE (command) 71 7181 CLOSED (response code) 99 7182 CONTACTADMIN (response code) 100 7183 COPY (command) 90 7184 COPYUID (response code) 100 7185 CORRUPTION (response code) 100 7186 COUNT (search result option) 74 7187 CREATE (command) 38 7189 D 7190 DELETE (command) 39 7191 DELETED (search key) 76 7192 DELETED (status item) 66 7193 DRAFT (search key) 76 7195 E 7196 ENABLE (command) 33 7197 ENVELOPE (fetch item) 89 7198 ENVELOPE (fetch result) 119 7199 ESEARCH (response) 113 7200 EXAMINE (command) 37 7201 EXPIRED (response code) 101 7202 EXPUNGE (command) 72 7203 EXPUNGE (response) 114 7204 EXPUNGEISSUED (response code) 101 7205 Envelope Structure (message attribute) 14 7207 F 7208 FAST (fetch item) 86 7209 FETCH (command) 85 7210 FETCH (response) 115 7211 FLAGGED (search key) 76 7212 FLAGS (fetch item) 89 7213 FLAGS (fetch result) 121 7214 FLAGS (response) 113 7215 FLAGS (store command data item) 90 7216 FLAGS.SILENT (store command data item) 90 7217 FROM (search key) 76 7218 FULL (fetch item) 86 7219 Flags (message attribute) 11 7221 H 7222 HASCHILDREN (response code) 101 7223 HEADER (part specifier) 87 7224 HEADER (search key) 76 7225 HEADER.FIELDS (part specifier) 87 7226 HEADER.FIELDS.NOT (part specifier) 87 7228 I 7229 IDLE (command) 69 7230 INTERNALDATE (fetch item) 89 7231 INTERNALDATE (fetch result) 121 7232 INUSE (response code) 101 7233 Internal Date (message attribute) 13 7235 K 7236 KEYWORD (search key) 77 7237 Keyword (type of flag) 12 7239 L 7240 LARGER (search key) 77 7241 LIMIT (response code) 102 7242 LIST (command) 43 7243 LIST (response) 108 7244 LOGOUT (command) 27 7246 M 7247 MAX (search result option) 74 7248 MAY (specification requirement term) 5 7249 MESSAGES (status item) 66 7250 MIME (part specifier) 88 7251 MIN (search result option) 74 7252 MOVE (command) 91 7253 MUST (specification requirement term) 5 7254 MUST NOT (specification requirement term) 5 7255 Message Sequence Number (message attribute) 11 7257 N 7258 NAMESPACE (command) 61 7259 NAMESPACE (response) 112 7260 NO (response) 105 7261 NONEXISTENT (response code) 102 7262 NOOP (command) 26 7263 NOPERM (response code) 102 7264 NOT (search key) 77 7265 NOT RECOMMENDED (specification requirement term) 5 7267 O 7268 OK (response) 105 7269 ON (search key) 77 7270 OPTIONAL (specification requirement term) 5 7271 OR (search key) 77 7272 OVERQUOTA (response code) 102 7274 P 7275 PARSE (response code) 102 7276 PERMANENTFLAGS (response code) 103 7277 PREAUTH (response) 106 7278 PRIVACYREQUIRED (response code) 103 7279 Permanent Flag (class of flag) 13 7280 Predefined keywords 12 7282 R 7283 READ-ONLY (response code) 103 7284 READ-WRITE (response code) 103 7285 RECOMMENDED (specification requirement term) 5 7286 RENAME (command) 40 7287 REQUIRED (specification requirement term) 5 7288 RFC822.SIZE (fetch item) 89 7289 RFC822.SIZE (fetch result) 121 7291 S 7292 SAVE (search result option) 74 7293 SEARCH (command) 73 7294 SEEN (search key) 77 7295 SELECT (command) 35 7296 SENTBEFORE (search key) 77 7297 SENTON (search key) 77 7298 SENTSINCE (search key) 77 7299 SERVERBUG (response code) 103 7300 SHOULD (specification requirement term) 5 7301 SHOULD NOT (specification requirement term) 5 7302 SINCE (search key) 77 7303 SIZE (status item) 66 7304 SMALLER (search key) 77 7305 STARTTLS (command) 28 7306 STATUS (command) 65 7307 STATUS (response) 113 7308 STORE (command) 89 7309 SUBJECT (search key) 77 7310 SUBSCRIBE (command) 42 7311 Session Flag (class of flag) 13 7312 System Flag (type of flag) 11 7314 T 7315 TEXT (part specifier) 87 7316 TEXT (search key) 77 7317 TO (search key) 77 7318 TRYCREATE (response code) 104 7320 U 7321 UID (command) 93 7322 UID (fetch item) 89 7323 UID (fetch result) 121 7324 UID (search key) 78 7325 UIDNEXT (response code) 104 7326 UIDNEXT (status item) 66 7327 UIDNOTSTICKY (response code) 104 7328 UIDVALIDITY (response code) 104 7329 UIDVALIDITY (status item) 66 7330 UNANSWERED (search key) 78 7331 UNAVAILABLE (response code) 104 7332 UNDELETED (search key) 78 7333 UNDRAFT (search key) 78 7334 UNFLAGGED (search key) 78 7335 UNKEYWORD (search key) 78 7336 UNKNOWN-CTE (response code) 105 7337 UNSEEN (search key) 78 7338 UNSEEN (status item) 66 7339 UNSELECT (command) 72 7340 UNSUBSCRIBE (command) 43 7341 Unique Identifier (UID) (message attribute) 9 7343 X 7344 X (command) 95 7346 [ 7347 [RFC-5322] Size (message attribute) 13 7349 \ 7350 \All (mailbox name attribute) 110 7351 \Answered (system flag) 11 7352 \Archive (mailbox name attribute) 110 7353 \Deleted (system flag) 12 7354 \Draft (system flag) 12 7355 \Drafts (mailbox name attribute) 111 7356 \Flagged (mailbox name attribute) 111 7357 \Flagged (system flag) 11 7358 \HasChildren (mailbox name attribute) 109 7359 \HasNoChildren (mailbox name attribute) 110 7360 \Junk (mailbox name attribute) 111 7361 \Marked (mailbox name attribute) 110 7362 \Noinferiors (mailbox name attribute) 109 7363 \NonExistent (mailbox name attribute) 109 7364 \Noselect (mailbox name attribute) 109 7365 \Recent (system flag) 12 7366 \Remote (mailbox name attribute) 110 7367 \Seen (system flag) 11 7368 \Sent (mailbox name attribute) 111 7369 \Subscribed (mailbox name attribute) 110 7370 \Trash (mailbox name attribute) 111 7371 \Unmarked (mailbox name attribute) 110 7373 Authors' Addresses 7375 Alexey Melnikov (editor) 7376 Isode Ltd 7377 14 Castle Mews 7378 Hampton, Middlesex TW12 2NP 7379 UK 7381 Email: Alexey.Melnikov@isode.com 7383 Barry Leiba (editor) 7384 Futurewei Technologies 7386 Phone: +1 646 827 0648 7387 Email: barryleiba@computer.org 7388 URI: http://internetmessagingtechnology.org/