idnits 2.17.1 draft-ietf-extra-imap4rev2-11.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 (December 3, 2019) is 1607 days in the past. 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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'IMAP2' is mentioned on line 6786, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 6781, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 6771, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 6776, but not defined == Missing Reference: 'RFC-822' is mentioned on line 6790, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-DISC' is mentioned on line 6728, but not defined == Missing Reference: 'SMTP' is mentioned on line 6749, but not defined == Missing Reference: 'RFC7888' is mentioned on line 6724, but not defined -- Looks like a reference, but probably isn't: '1' on line 840 == Missing Reference: 'IMAP-URL' is mentioned on line 6763, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5586, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1669, but not defined == Missing Reference: 'RFC5258' is mentioned on line 6710, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6715, but not defined == Missing Reference: 'RFC3348' is mentioned on line 6719, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 6756, but not defined == Missing Reference: 'UIDNEXT 2' is mentioned on line 3129, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3200, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 6733, but not defined == Missing Reference: 'HEADER' is mentioned on line 5603, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3773, but not defined == Missing Reference: 'UID' is mentioned on line 4183, but not defined == Missing Reference: 'RFC2087' is mentioned on line 6760, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'READ-WRITE' is mentioned on line 5587, but not defined == Missing Reference: 'RFC4422' is mentioned on line 5923, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6009, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6075, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 6794, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6705, but not defined == Missing Reference: 'IMAP-MODEL' is mentioned on line 6739, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 6813, but not defined == Missing Reference: 'RFC3516' is mentioned on line 6903, 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: 9 errors (**), 0 flaws (~~), 33 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 Huawei Technologies 6 Expires: June 5, 2020 December 3, 2019 8 INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev2 9 draft-ietf-extra-imap4rev2-11 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 June 5, 2020. 48 Copyright Notice 50 Copyright (c) 2019 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 . . . . . . . . . . . 12 90 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 13 91 2.3.5. Envelope Structure Message Attribute . . . . . . . . 13 92 2.3.6. Body Structure Message Attribute . . . . . . . . . . 13 93 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 13 94 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 13 95 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 13 96 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 14 97 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 14 98 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 14 99 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 16 100 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 16 101 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 16 102 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 16 103 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 16 104 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 17 105 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 18 106 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 107 5. Operational Considerations . . . . . . . . . . . . . . . . . 19 108 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 19 109 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 20 110 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 20 111 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 21 112 5.3. Response when no Command in Progress . . . . . . . . . . 22 113 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 22 114 5.5. Multiple Commands in Progress (Command Pipelining) . . . 22 115 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 24 116 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 24 117 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 24 118 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 25 119 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 26 120 6.2. Client Commands - Not Authenticated State . . . . . . . . 26 121 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 27 122 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 28 123 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 31 124 6.3. Client Commands - Authenticated State . . . . . . . . . . 32 125 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 32 126 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 34 127 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 36 128 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 37 129 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 38 130 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 39 131 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 41 132 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 42 133 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 42 134 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 60 135 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 . . . . . . . . . . . . . . . . . . . 112 163 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 . . . . . . . . . . . . . . . . . 121 172 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 122 173 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 139 174 11. Security Considerations . . . . . . . . . . . . . . . . . . . 139 175 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 140 176 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 140 177 11.3. LIST command and Other Users' namespace . . . . . . . . 140 178 11.4. Other Security Considerations . . . . . . . . . . . . . 141 179 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 141 180 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 . . . . . . . 147 188 A.1. Mailbox International Naming Convention for compatibility 189 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 148 190 Appendix B. Backward compatibility with BINARY extension . . . . 149 191 Appendix C. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 150 192 Appendix D. Acknowledgement . . . . . . . . . . . . . . . . . . 152 193 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 194 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 157 196 1. How to Read This Document 198 1.1. Organization of This Document 200 This document is written from the point of view of the implementor of 201 an IMAP4rev2 client or server. Beyond the protocol overview in 202 section 2, it is not optimized for someone trying to understand the 203 operation of the protocol. The material in sections 3 through 5 204 provides the general context and definitions with which IMAP4rev2 205 operates. 207 Sections 6, 7, and 9 describe the IMAP commands, responses, and 208 syntax, respectively. The relationships among these are such that it 209 is almost impossible to understand any of them separately. In 210 particular, do not attempt to deduce command syntax from the command 211 section alone; instead refer to the Formal Syntax section. 213 1.2. Conventions Used in This Document 215 "Conventions" are basic principles or procedures. Document 216 conventions are noted in this section. 218 In examples, "C:" and "S:" indicate lines sent by the client and 219 server respectively. 221 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 222 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 223 "OPTIONAL" in this document are to be interpreted as described in BCP 224 14 [RFC2119] [RFC8174] when, and only when, they appear in all 225 capitals, as shown here. 227 The word "can" (not "may") is used to refer to a possible 228 circumstance or situation, as opposed to an optional facility of the 229 protocol. 231 "User" is used to refer to a human user, whereas "client" refers to 232 the software being run by the user. 234 "Connection" refers to the entire sequence of client/server 235 interaction from the initial establishment of the network connection 236 until its termination. 238 "Session" refers to the sequence of client/server interaction from 239 the time that a mailbox is selected (SELECT or EXAMINE command) until 240 the time that selection ends (SELECT or EXAMINE of another mailbox, 241 CLOSE command, UNSELECT command, or connection termination). 243 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 244 unless otherwise specified. Other character sets are indicated using 245 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 246 CHARSETs have important additional semantics in addition to defining 247 character set; refer to these documents for more detail. 249 There are several protocol conventions in IMAP. These refer to 250 aspects of the specification which are not strictly part of the IMAP 251 protocol, but reflect generally-accepted practice. Implementations 252 need to be aware of these conventions, and avoid conflicts whether or 253 not they implement the convention. For example, "&" may not be used 254 as a hierarchy delimiter since it conflicts with the Mailbox 255 International Naming Convention, and other uses of "&" in mailbox 256 names are impacted as well. 258 1.3. Special Notes to Implementors 260 Implementors of the IMAP protocol are strongly encouraged to read the 261 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 262 conjunction with this document, to help understand the intricacies of 263 this protocol and how best to build an interoperable product. 265 IMAP4rev2 is designed to be upwards compatible from the [IMAP2] and 266 unpublished IMAP2bis protocols. IMAP4rev2 is largely compatible with 267 the IMAP4rev1 protocol described in RFC 3501 and the IMAP4 protocol 268 described in RFC 1730; the exception being in certain facilities 269 added in RFC 1730 that proved problematic and were subsequently 270 removed. In the course of the evolution of IMAP4rev2, some aspects 271 in the earlier protocols have become obsolete. Obsolete commands, 272 responses, and data formats which an IMAP4rev2 implementation can 273 encounter when used with an earlier implementation are described in 274 Appendix C and [IMAP-OBSOLETE]. 276 Other compatibility issues with IMAP2bis, the most common variant of 277 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 278 discussion of compatibility issues with rare (and presumed extinct) 279 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 280 primarily of historical interest. 282 IMAP was originally developed for the older [RFC-822] standard, and 283 as a consequence several fetch items in IMAP incorporate "RFC822" in 284 their name. In all cases, "RFC822" should be interpreted as a 285 reference to the updated [RFC-5322] standard. 287 2. Protocol Overview 289 2.1. Link Level 291 The IMAP4rev2 protocol assumes a reliable data stream such as that 292 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 293 port 143. 295 2.2. Commands and Responses 297 An IMAP4rev2 connection consists of the establishment of a client/ 298 server network connection, an initial greeting from the server, and 299 client/server interactions. These client/server interactions consist 300 of a client command, server data, and a server completion result 301 response. 303 All interactions transmitted by client and server are in the form of 304 lines, that is, strings that end with a CRLF. The protocol receiver 305 of an IMAP4rev2 client or server is either reading a line, or is 306 reading a sequence of octets with a known count followed by a line. 308 2.2.1. Client Protocol Sender and Server Protocol Receiver 310 The client command begins an operation. Each client command is 311 prefixed with an identifier (typically a short alphanumeric string, 312 e.g., A0001, A0002, etc.) called a "tag". A different tag is 313 generated by the client for each command. 315 Clients MUST follow the syntax outlined in this specification 316 strictly. It is a syntax error to send a command with missing or 317 extraneous spaces or arguments. 319 There are two cases in which a line from the client does not 320 represent a complete command. In one case, a command argument is 321 quoted with an octet count (see the description of literal in String 322 under Data Formats); in the other case, the command arguments require 323 server feedback (see the AUTHENTICATE command). In either case, the 324 server sends a command continuation request response if it is ready 325 for the octets (if appropriate) and the remainder of the command. 326 This response is prefixed with the token "+". 328 Note: If instead, the server detected an error in the command, it 329 sends a BAD completion response with a tag matching the command 330 (as described below) to reject the command and prevent the client 331 from sending any more of the command. 333 It is also possible for the server to send a completion response 334 for some other command (if multiple commands are in progress), or 335 untagged data. In either case, the command continuation request 336 is still pending; the client takes the appropriate action for the 337 response, and reads another response from the server. In all 338 cases, the client MUST send a complete command (including 339 receiving all command continuation request responses and command 340 continuations for the command) before initiating a new command. 342 The protocol receiver of an IMAP4rev2 server reads a command line 343 from the client, parses the command and its arguments, and transmits 344 server data and a server command completion result response. 346 2.2.2. Server Protocol Sender and Client Protocol Receiver 348 Data transmitted by the server to the client and status responses 349 that do not indicate command completion are prefixed with the token 350 "*", and are called untagged responses. 352 Server data MAY be sent as a result of a client command, or MAY be 353 sent unilaterally by the server. There is no syntactic difference 354 between server data that resulted from a specific command and server 355 data that were sent unilaterally. 357 The server completion result response indicates the success or 358 failure of the operation. It is tagged with the same tag as the 359 client command which began the operation. Thus, if more than one 360 command is in progress, the tag in a server completion response 361 identifies the command to which the response applies. There are 362 three possible server completion responses: OK (indicating success), 363 NO (indicating failure), or BAD (indicating a protocol error such as 364 unrecognized command or command syntax error). 366 Servers SHOULD enforce the syntax outlined in this specification 367 strictly. Any client command with a protocol syntax error, including 368 (but not limited to) missing or extraneous spaces or arguments, 369 SHOULD be rejected, and the client given a BAD server completion 370 response. 372 The protocol receiver of an IMAP4rev2 client reads a response line 373 from the server. It then takes action on the response based upon the 374 first token of the response, which can be a tag, a "*", or a "+". 376 A client MUST be prepared to accept any server response at all times. 377 This includes server data that was not requested. Server data SHOULD 378 be recorded, so that the client can reference its recorded copy 379 rather than sending a command to the server to request the data. In 380 the case of certain server data, the data MUST be recorded. 382 This topic is discussed in greater detail in the Server Responses 383 section. 385 2.3. Message Attributes 387 In addition to message text, each message has several attributes 388 associated with it. These attributes can be retrieved individually 389 or in conjunction with other attributes or message texts. 391 2.3.1. Message Numbers 393 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 394 identifier or the message sequence number. 396 2.3.1.1. Unique Identifier (UID) Message Attribute 398 An unsigned 32-bit value assigned to each message, which when used 399 with the unique identifier validity value (see below) forms a 64-bit 400 value that MUST NOT refer to any other message in the mailbox or any 401 subsequent mailbox with the same name forever. Unique identifiers 402 are assigned in a strictly ascending fashion in the mailbox; as each 403 message is added to the mailbox it is assigned a higher UID than the 404 message(s) which were added previously. Unlike message sequence 405 numbers, unique identifiers are not necessarily contiguous. 407 The unique identifier of a message MUST NOT change during the 408 session, and SHOULD NOT change between sessions. Any change of 409 unique identifiers between sessions MUST be detectable using the 410 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 411 are required for a client to resynchronize its state from a previous 412 session with the server (e.g., disconnected or offline access 413 clients); this is discussed further in [IMAP-DISC]. 415 Associated with every mailbox are two 32-bit unsigned values which 416 aid in unique identifier handling: the next unique identifier value 417 (UIDNEXT) and the unique identifier validity value (UIDVALIDITY). 419 The next unique identifier value is the predicted value that will be 420 assigned to a new message in the mailbox. Unless the unique 421 identifier validity also changes (see below), the next unique 422 identifier value MUST have the following two characteristics. First, 423 the next unique identifier value MUST NOT change unless new messages 424 are added to the mailbox; and second, the next unique identifier 425 value MUST change whenever new messages are added to the mailbox, 426 even if those new messages are subsequently expunged. 428 Note: The next unique identifier value is intended to provide a 429 means for a client to determine whether any messages have been 430 delivered to the mailbox since the previous time it checked this 431 value. It is not intended to provide any guarantee that any 432 message will have this unique identifier. A client can only 433 assume, at the time that it obtains the next unique identifier 434 value, that messages arriving after that time will have a UID 435 greater than or equal to that value. 437 The unique identifier validity value is sent in a UIDVALIDITY 438 response code in an OK untagged response at mailbox selection time. 439 If unique identifiers from an earlier session fail to persist in this 440 session, the unique identifier validity value MUST be greater than 441 the one used in the earlier session. 443 Note: Ideally, unique identifiers SHOULD persist at all times. 444 Although this specification recognizes that failure to persist can 445 be unavoidable in certain server environments, it STRONGLY 446 ENCOURAGES message store implementation techniques that avoid this 447 problem. For example: 449 1. Unique identifiers MUST be strictly ascending in the mailbox 450 at all times. If the physical message store is re-ordered by 451 a non-IMAP agent, this requires that the unique identifiers in 452 the mailbox be regenerated, since the former unique 453 identifiers are no longer strictly ascending as a result of 454 the re-ordering. 456 2. If the message store has no mechanism to store unique 457 identifiers, it must regenerate unique identifiers at each 458 session, and each session must have a unique UIDVALIDITY 459 value. 461 3. If the mailbox is deleted and a new mailbox with the same name 462 is created at a later date, the server must either keep track 463 of unique identifiers from the previous instance of the 464 mailbox, or it must assign a new UIDVALIDITY value to the new 465 instance of the mailbox. A good UIDVALIDITY value to use in 466 this case is a 32-bit representation of the creation date/time 467 of the mailbox. It is alright to use a constant such as 1, 468 but only if it guaranteed that unique identifiers will never 469 be reused, even in the case of a mailbox being deleted (or 470 renamed) and a new mailbox by the same name created at some 471 future time. 473 4. The combination of mailbox name, UIDVALIDITY, and UID must 474 refer to a single immutable message on that server forever. 475 In particular, the internal date, [RFC-5322] size, envelope, 476 body structure, and message texts (all BODY[...] fetch data 477 items) must never change. This does not include message 478 numbers, nor does it include attributes that can be set by a 479 STORE command (e.g., FLAGS). 481 2.3.1.2. Message Sequence Number Message Attribute 483 A relative position from 1 to the number of messages in the mailbox. 484 This position MUST be ordered by ascending unique identifier. As 485 each new message is added, it is assigned a message sequence number 486 that is 1 higher than the number of messages in the mailbox before 487 that new message was added. 489 Message sequence numbers can be reassigned during the session. For 490 example, when a message is permanently removed (expunged) from the 491 mailbox, the message sequence number for all subsequent messages is 492 decremented. The number of messages in the mailbox is also 493 decremented. Similarly, a new message can be assigned a message 494 sequence number that was once held by some other message prior to an 495 expunge. 497 In addition to accessing messages by relative position in the 498 mailbox, message sequence numbers can be used in mathematical 499 calculations. For example, if an untagged "11 EXISTS" is received, 500 and previously an untagged "8 EXISTS" was received, three new 501 messages have arrived with message sequence numbers of 9, 10, and 11. 502 Another example, if message 287 in a 523 message mailbox has UID 503 12345, there are exactly 286 messages which have lesser UIDs and 236 504 messages which have greater UIDs. 506 2.3.2. Flags Message Attribute 508 A list of zero or more named tokens associated with the message. A 509 flag is set by its addition to this list, and is cleared by its 510 removal. There are two types of flags in IMAP4rev2. A flag of 511 either type can be permanent or session-only. 513 A system flag is a flag name that is pre-defined in this 514 specification and begin with "\". 516 Certain system flags (\Deleted and \Seen) have special semantics 517 described elsewhere in this document. The currently-defined system 518 flags are: 520 \Seen Message has been read 522 \Answered Message has been answered 524 \Flagged Message is "flagged" for urgent/special attention 525 \Deleted Message is "deleted" for removal by later EXPUNGE 527 \Draft Message has not completed composition (marked as a draft). 529 \Recent This flag was in used in IMAP4rev1 and is now deprecated. 531 A keyword is defined by the server implementation. Keywords do not 532 begin with "\". Servers MAY permit the client to define new keywords 533 in the mailbox (see the description of the PERMANENTFLAGS response 534 code for more information). Some keywords that start with "$" are 535 also defined in this specification. 537 This document defines several keywords that were not originally 538 defined in RFC 3501, but which were found to be useful by client 539 implementations. These keywords SHOULD be supported (i.e. allowed in 540 APPEND, COPY, MOVE and SEARCH commands) by server implementations: 542 $Forwarded Message has been forwarded to another email address, 543 embedded within or attached to a new message. An email client 544 sets this keyword when it successfully forwards the message to 545 another email address. Typical usage of this keyword is to show a 546 different (or additional) icon for a message that has been 547 forwarded. Once set, the flag SHOULD NOT be cleared. 549 $Forwarded 551 $Forwarded 553 $MDNSent Message Disposition Notification [RFC8098] was generated 554 and sent for this message. 556 $MDNSent 558 A flag can be permanent or session-only on a per-flag basis. 559 Permanent flags are those which the client can add or remove from the 560 message flags permanently; that is, concurrent and subsequent 561 sessions will see any change in permanent flags. Changes to session 562 flags are valid only in that session. 564 2.3.3. Internal Date Message Attribute 566 The internal date and time of the message on the server. This is not 567 the date and time in the [RFC-5322] header, but rather a date and 568 time which reflects when the message was received. In the case of 569 messages delivered via [SMTP], this SHOULD be the date and time of 570 final delivery of the message as defined by [SMTP]. In the case of 571 messages delivered by the IMAP4rev2 COPY or MOVE command, this SHOULD 572 be the internal date and time of the source message. In the case of 573 messages delivered by the IMAP4rev2 APPEND command, this SHOULD be 574 the date and time as specified in the APPEND command description. 575 All other cases are implementation defined. 577 2.3.4. [RFC-5322] Size Message Attribute 579 The number of octets in the message, as expressed in [RFC-5322] 580 format. 582 2.3.5. Envelope Structure Message Attribute 584 A parsed representation of the [RFC-5322] header of the message. 585 Note that the IMAP Envelope structure is not the same as an [SMTP] 586 envelope. 588 2.3.6. Body Structure Message Attribute 590 A parsed representation of the [MIME-IMB] body structure information 591 of the message. 593 2.4. Message Texts 595 In addition to being able to fetch the full [RFC-5322] text of a 596 message, IMAP4rev2 permits the fetching of portions of the full 597 message text. Specifically, it is possible to fetch the [RFC-5322] 598 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 599 [MIME-IMB] header. 601 3. State and Flow Diagram 603 Once the connection between client and server is established, an 604 IMAP4rev2 connection is in one of four states. The initial state is 605 identified in the server greeting. Most commands are only valid in 606 certain states. It is a protocol error for the client to attempt a 607 command while the connection is in an inappropriate state, and the 608 server will respond with a BAD or NO (depending upon server 609 implementation) command completion result. 611 3.1. Not Authenticated State 613 In the not authenticated state, the client MUST supply authentication 614 credentials before most commands will be permitted. This state is 615 entered when a connection starts unless the connection has been pre- 616 authenticated. 618 3.2. Authenticated State 620 In the authenticated state, the client is authenticated and MUST 621 select a mailbox to access before commands that affect messages will 622 be permitted. This state is entered when a pre-authenticated 623 connection starts, when acceptable authentication credentials have 624 been provided, after an error in selecting a mailbox, or after a 625 successful CLOSE command. 627 3.3. Selected State 629 In a selected state, a mailbox has been selected to access. This 630 state is entered when a mailbox has been successfully selected. 632 3.4. Logout State 634 In the logout state, the connection is being terminated. This state 635 can be entered as a result of a client request (via the LOGOUT 636 command) or by unilateral action on the part of either the client or 637 server. 639 If the client requests the logout state, the server MUST send an 640 untagged BYE response and a tagged OK response to the LOGOUT command 641 before the server closes the connection; and the client MUST read the 642 tagged OK response to the LOGOUT command before the client closes the 643 connection. 645 A server SHOULD NOT unilaterally close the connection without sending 646 an untagged BYE response that contains the reason for having done so. 647 A client SHOULD NOT unilaterally close the connection, and instead 648 SHOULD issue a LOGOUT command. If the server detects that the client 649 has unilaterally closed the connection, the server MAY omit the 650 untagged BYE response and simply close its connection. 652 +----------------------+ 653 |connection established| 654 +----------------------+ 655 || 656 \/ 657 +--------------------------------------+ 658 | server greeting | 659 +--------------------------------------+ 660 || (1) || (2) || (3) 661 \/ || || 662 +-----------------+ || || 663 |Not Authenticated| || || 664 +-----------------+ || || 665 || (7) || (4) || || 666 || \/ \/ || 667 || +----------------+ || 668 || | Authenticated |<=++ || 669 || +----------------+ || || 670 || || (7) || (5) || (6) || 671 || || \/ || || 672 || || +--------+ || || 673 || || |Selected|==++ || 674 || || +--------+ || 675 || || || (7) || 676 \/ \/ \/ \/ 677 +--------------------------------------+ 678 | Logout | 679 +--------------------------------------+ 680 || 681 \/ 682 +-------------------------------+ 683 |both sides close the connection| 684 +-------------------------------+ 686 (1) connection without pre-authentication (OK greeting) 687 (2) pre-authenticated connection (PREAUTH greeting) 688 (3) rejected connection (BYE greeting) 689 (4) successful LOGIN or AUTHENTICATE command 690 (5) successful SELECT or EXAMINE command 691 (6) CLOSE command, unsolicited CLOSED response code or 692 failed SELECT or EXAMINE command 693 (7) LOGOUT command, server shutdown, or connection closed 695 4. Data Formats 697 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 698 be in one of several forms: atom, number, string, parenthesized list, 699 or NIL. Note that a particular data item may take more than one 700 form; for example, a data item defined as using "astring" syntax may 701 be either an atom or a string. 703 4.1. Atom 705 An atom consists of one or more non-special characters. 707 4.1.1. Sequence set and UID set 709 A set of messages can be referenced by a sequence set containing 710 either message sequence numbers or unique identifiers. See Section 9 711 for details. Sequence sets can contain ranges (e.g. "5:50"), an 712 enumeration of specific message/UID numbers, a special symbol "*", or 713 a combination of the above. 715 A "UID set" is similar to the sequence set of unique identifiers; 716 however, the "*" value for a sequence number is not permitted. 718 4.2. Number 720 A number consists of one or more digit characters, and represents a 721 numeric value. 723 4.3. String 725 A string is in one of three forms: synchonizing literal, non- 726 synchronizing literal or quoted string. The synchronizing literal 727 form is the general form of string. The non-synchronizing literal 728 form is also the general form, but has length limitation. The quoted 729 string form is an alternative that avoids the overhead of processing 730 a literal at the cost of limitations of characters which may be used. 732 When the distinction between synchronizing and non-synchronizing 733 literals is not important, this document just uses the term 734 "literal". 736 A synchronizing literal is a sequence of zero or more octets 737 (including CR and LF), prefix-quoted with an octet count in the form 738 of an open brace ("{"), the number of octets, close brace ("}"), and 739 CRLF. In the case of synchronizing literals transmitted from server 740 to client, the CRLF is immediately followed by the octet data. In 741 the case of synchronizing literals transmitted from client to server, 742 the client MUST wait to receive a command continuation request 743 (described later in this document) before sending the octet data (and 744 the remainder of the command). 746 The non-synchronizing literal is an alternate form of synchronizing 747 literal, and it may appear in communication from client to server 748 instead of the synchonizing form of literal. The non-synchronizing 749 literal form MUST NOT be sent from server to client. The non- 750 synchronizing literal is distinguished from the synchronizing literal 751 by having a plus ("+") between the octet count and the closing brace 752 ("}"). The server does not generate a command continuation request 753 in response to a non-synchronizing literal, and clients are not 754 required to wait before sending the octets of a non- synchronizing 755 literal. Non-synchronizing literals MUST NOT be larger than 4096 756 octets. Any literal larger than 4096 bytes MUST be sent as a 757 synchronizing literal. (Non-synchronizing literals defined in this 758 document are the same as non-synchronizing literals defined by the 759 LITERAL- extension from [RFC7888]. See that document for details on 760 how to handle invalid non-synchronizing literals longer than 4096 761 octets and for interaction with other IMAP extensions.) 763 A quoted string is a sequence of zero or more Unicode characters, 764 excluding CR and LF, encoded in UTF-8, with double quote (<">) 765 characters at each end. 767 The empty string is represented as "" (a quoted string with zero 768 characters between double quotes), as {0} followed by CRLF (a 769 synchronizing literal with an octet count of 0) or as {0+} followed 770 by CRLF (a non-synchronizing literal with an octet count of 0). 772 Note: Even if the octet count is 0, a client transmitting a 773 synchronizing literal MUST wait to receive a command continuation 774 request. 776 4.3.1. 8-bit and Binary Strings 778 8-bit textual and binary mail is supported through the use of a 779 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 780 transmit 8-bit or multi-octet characters in literals, but SHOULD do 781 so only when the [CHARSET] is identified. 783 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 784 identified charset for header-field values with 8-bit content is 785 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 786 transmit [UTF-8] text in quoted-strings as long as the string does 787 not contain NUL, CR, or LF. This differs from IMAP4rev1 788 implementations. 790 Although a BINARY content transfer encoding is defined, unencoded 791 binary strings are not permitted, unless returned in a in 792 response to BINARY.PEEK[]<> or 793 BINARY[]<> FETCH data item. A "binary 794 string" is any string with NUL characters. A string with an 795 excessive amount of CTL characters MAY also be considered to be 796 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 797 FETCH, client and server implementations MUST encode binary data into 798 a textual form, such as BASE64, before transmitting the data. 800 4.4. Parenthesized List 802 Data structures are represented as a "parenthesized list"; a sequence 803 of data items, delimited by space, and bounded at each end by 804 parentheses. A parenthesized list can contain other parenthesized 805 lists, using multiple levels of parentheses to indicate nesting. 807 The empty list is represented as () -- a parenthesized list with no 808 members. 810 4.5. NIL 812 The special form "NIL" represents the non-existence of a particular 813 data item that is represented as a string or parenthesized list, as 814 distinct from the empty string "" or the empty parenthesized list (). 816 Note: NIL is never used for any data item which takes the form of 817 an atom. For example, a mailbox name of "NIL" is a mailbox named 818 NIL as opposed to a non-existent mailbox name. This is because 819 mailbox uses "astring" syntax which is an atom or a string. 820 Conversely, an addr-name of NIL is a non-existent personal name, 821 because addr-name uses "nstring" syntax which is NIL or a string, 822 but never an atom. 824 Examples: 826 The following LIST response: 828 * LIST () "/" NIL 830 is equivalent to: 831 * LIST () "/" "NIL" 833 as LIST response ABNF is using astring for mailbox name. 835 However, the following response 837 * FETCH 1 (BODY[1] NIL) 839 is not equivalent to: 840 * FETCH 1 (BODY[1] "NIL") 841 The former means absence of the body part, while the latter 842 means that it contains literal sequence of characters "NIL". 844 5. Operational Considerations 846 The following rules are listed here to ensure that all IMAP4rev2 847 implementations interoperate properly. 849 5.1. Mailbox Naming 851 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 852 (this differs from IMAP4rev1). Client implementations MAY attempt to 853 create Net-Unicode mailbox names, and MUST interpret any 8-bit 854 mailbox names returned by LIST as [NET-UNICODE]. Server 855 implementations MUST prohibit the creation of 8-bit mailbox names 856 that do not comply with Net-Unicode (however, servers MAY accept a 857 de-normalized UTF-8 mailbox name and convert it to Net-Unicode prior 858 to mailbox creation). 860 The case-insensitive mailbox name INBOX is a special name reserved to 861 mean "the primary mailbox for this user on this server". (Note that 862 this special name may not exist on some servers for some users, for 863 example if the user has no access to personal namespace.) The 864 interpretation of all other names is implementation-dependent. 866 In particular, this specification takes no position on case 867 sensitivity in non-INBOX mailbox names. Some server implementations 868 are fully case-sensitive in ASCII range; others preserve case of a 869 newly-created name but otherwise are case-insensitive; and yet others 870 coerce names to a particular case. Client implementations MUST 871 interact with any of these. 873 There are certain client considerations when creating a new mailbox 874 name: 876 1. Any character which is one of the atom-specials (see the Formal 877 Syntax) will require that the mailbox name be represented as a 878 quoted string or literal. 880 2. CTL and other non-graphic characters are difficult to represent 881 in a user interface and are best avoided. Servers MAY refuse to 882 create mailbox names containing Unicode CTL characters. 884 3. Although the list-wildcard characters ("%" and "*") are valid in 885 a mailbox name, it is difficult to use such mailbox names with 886 the LIST command due to the conflict with wildcard 887 interpretation. 889 4. Usually, a character (determined by the server implementation) is 890 reserved to delimit levels of hierarchy. 892 5. Two characters, "#" and "&", have meanings by convention, and 893 should be avoided except when used in that convention. 895 5.1.1. Mailbox Hierarchy Naming 897 If it is desired to export hierarchical mailbox names, mailbox names 898 MUST be left-to-right hierarchical using a single character to 899 separate levels of hierarchy. The same hierarchy separator character 900 is used for all levels of hierarchy within a single name. 902 5.1.2. Namespaces 904 Personal Namespace: A namespace that the server considers within the 905 personal scope of the authenticated user on a particular connection. 906 Typically, only the authenticated user has access to mailboxes in 907 their Personal Namespace. It is the part of the namespace that 908 belongs to the user that is allocated for mailboxes. If an INBOX 909 exists for a user, it MUST appear within the user's personal 910 namespace. In the typical case, there SHOULD be only one Personal 911 Namespace on a server. 913 Other Users' Namespace: A namespace that consists of mailboxes from 914 the Personal Namespaces of other users. To access mailboxes in the 915 Other Users' Namespace, the currently authenticated user MUST be 916 explicitly granted access rights. For example, it is common for a 917 manager to grant to their secretary access rights to their mailbox. 918 In the typical case, there SHOULD be only one Other Users' Namespace 919 on a server. 921 Shared Namespace: A namespace that consists of mailboxes that are 922 intended to be shared amongst users and do not exist within a user's 923 Personal Namespace. 925 The namespaces a server uses MAY differ on a per-user basis. 927 5.1.2.1. Historic Mailbox Namespace Naming Convention 929 By convention, the first hierarchical element of any mailbox name 930 which begins with "#" identifies the "namespace" of the remainder of 931 the name. This makes it possible to disambiguate between different 932 types of mailbox stores, each of which have their own namespaces. 934 For example, implementations which offer access to USENET 935 newsgroups MAY use the "#news" namespace to partition the USENET 936 newsgroup namespace from that of other mailboxes. Thus, the 937 comp.mail.misc newsgroup would have a mailbox name of 938 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 939 a different object (e.g., a user's private mailbox). 941 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 942 friendly requiring the "#" character to be represented as %23 when 943 within URLs. As such, server implementers MAY instead consider using 944 namespace prefixes that do not contain the "#" character. 946 5.1.2.2. Common namespace models 948 Previous version of this protocol does not define a default server 949 namespace. Two common namespace models have evolved: 951 The "Personal Mailbox" model, in which the default namespace that is 952 presented consists of only the user's personal mailboxes. To access 953 shared mailboxes, the user must use an escape mechanism to reach 954 another namespace. 956 The "Complete Hierarchy" model, in which the default namespace that 957 is presented includes the user's personal mailboxes along with any 958 other mailboxes they have access to. 960 5.2. Mailbox Size and Message Status Updates 962 At any time, a server can send data that the client did not request. 963 Sometimes, such behavior is REQUIRED. For example, agents other than 964 the server MAY add messages to the mailbox (e.g., new message 965 delivery), change the flags of the messages in the mailbox (e.g., 966 simultaneous access to the same mailbox by multiple agents), or even 967 remove messages from the mailbox. A server MUST send mailbox size 968 updates automatically if a mailbox size change is observed during the 969 processing of a command. A server SHOULD send message flag updates 970 automatically, without requiring the client to request such updates 971 explicitly. 973 Special rules exist for server notification of a client about the 974 removal of messages to prevent synchronization errors; see the 975 description of the EXPUNGE response for more detail. In particular, 976 it is NOT permitted to send an EXISTS response that would reduce the 977 number of messages in the mailbox; only the EXPUNGE response can do 978 this. 980 Regardless of what implementation decisions a client makes on 981 remembering data from the server, a client implementation MUST record 982 mailbox size updates. It MUST NOT assume that any command after the 983 initial mailbox selection will return the size of the mailbox. 985 5.3. Response when no Command in Progress 987 Server implementations are permitted to send an untagged response 988 (except for EXPUNGE) while there is no command in progress. Server 989 implementations that send such responses MUST deal with flow control 990 considerations. Specifically, they MUST either (1) verify that the 991 size of the data does not exceed the underlying transport's available 992 window size, or (2) use non-blocking writes. 994 5.4. Autologout Timer 996 If a server has an inactivity autologout timer that applies to 997 sessions after authentication, the duration of that timer MUST be at 998 least 30 minutes. The receipt of ANY command from the client during 999 that interval SHOULD suffice to reset the autologout timer. 1001 5.5. Multiple Commands in Progress (Command Pipelining) 1003 The client MAY send another command without waiting for the 1004 completion result response of a command, subject to ambiguity rules 1005 (see below) and flow control constraints on the underlying data 1006 stream. Similarly, a server MAY begin processing another command 1007 before processing the current command to completion, subject to 1008 ambiguity rules. However, any command continuation request responses 1009 and command continuations MUST be negotiated before any subsequent 1010 command is initiated. 1012 The exception is if an ambiguity would result because of a command 1013 that would affect the results of other commands. 1015 If the server detects a possible ambiguity, it MUST execute commands 1016 to completion in the order given by the client. 1018 The most obvious example of ambiguity is when a command would affect 1019 the results of another command, e.g., a FETCH of a message's flags 1020 and a STORE of that same message's flags. 1022 A non-obvious ambiguity occurs with commands that permit an untagged 1023 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1024 since an untagged EXPUNGE response can invalidate sequence numbers in 1025 a subsequent command. This is not a problem for FETCH, STORE, or 1026 SEARCH commands because servers are prohibited from sending EXPUNGE 1027 responses while any of those commands are in progress. Therefore, if 1028 the client sends any command other than FETCH, STORE, or SEARCH, it 1029 MUST wait for the completion result response before sending a command 1030 with message sequence numbers. 1032 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1033 and UID SEARCH are in progress. If the client sends a UID 1034 command, it MUST wait for a completion result response before 1035 sending a command which uses message sequence numbers (this may 1036 include UID SEARCH). Any message sequence numbers in an argument 1037 to UID SEARCH are associated with messages prior to the effect of 1038 any untagged EXPUNGE returned by the UID SEARCH. 1040 For example, the following non-waiting command sequences are invalid: 1042 FETCH + NOOP + STORE 1044 STORE + COPY + FETCH 1046 COPY + COPY 1048 The following are examples of valid non-waiting command sequences: 1050 FETCH + STORE + SEARCH + NOOP 1052 STORE + COPY + EXPUNGE 1054 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1055 command sequence, depending upon whether or not the second UID 1056 SEARCH contains message sequence numbers. 1058 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1059 dependency between two commands. See Section 6.4.4.2 for more 1060 considerations about pipelining such dependent commands. 1062 6. Client Commands 1064 IMAP4rev2 commands are described in this section. Commands are 1065 organized by the state in which the command is permitted. Commands 1066 which are permitted in multiple states are listed in the minimum 1067 permitted state (for example, commands valid in authenticated and 1068 selected state are listed in the authenticated state commands). 1070 Command arguments, identified by "Arguments:" in the command 1071 descriptions below, are described by function, not by syntax. The 1072 precise syntax of command arguments is described in the Formal Syntax 1073 (Section 9). 1075 Some commands cause specific server responses to be returned; these 1076 are identified by "Responses:" in the command descriptions below. 1077 See the response descriptions in the Responses section for 1078 information on these responses, and the Formal Syntax section for the 1079 precise syntax of these responses. It is possible for server data to 1080 be transmitted as a result of any command. Thus, commands that do 1081 not specifically require server data specify "no specific responses 1082 for this command" instead of "none". 1084 The "Result:" in the command description refers to the possible 1085 tagged status responses to a command, and any special interpretation 1086 of these status responses. 1088 The state of a connection is only changed by successful commands 1089 which are documented as changing state. A rejected command (BAD 1090 response) never changes the state of the connection or of the 1091 selected mailbox. A failed command (NO response) generally does not 1092 change the state of the connection or of the selected mailbox; the 1093 exception being the SELECT and EXAMINE commands. 1095 6.1. Client Commands - Any State 1097 The following commands are valid in any state: CAPABILITY, NOOP, and 1098 LOGOUT. 1100 6.1.1. CAPABILITY Command 1102 Arguments: none 1104 Responses: REQUIRED untagged response: CAPABILITY 1106 Result: OK - capability completed 1107 BAD - command unknown or arguments invalid 1109 The CAPABILITY command requests a listing of capabilities that the 1110 server supports. The server MUST send a single untagged CAPABILITY 1111 response with "IMAP4rev2" as one of the listed capabilities before 1112 the (tagged) OK response. 1114 A capability name which begins with "AUTH=" indicates that the server 1115 supports that particular authentication mechanism. All such names 1116 are, by definition, part of this specification. For example, the 1117 authorization capability for an experimental "blurdybloop" 1118 authenticator would be "AUTH=XBLURDYBLOOP" and not 1119 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1121 Other capability names refer to extensions, revisions, or amendments 1122 to this specification. See the documentation of the CAPABILITY 1123 response for additional information. No capabilities, beyond the 1124 base IMAP4rev2 set defined in this specification, are enabled without 1125 explicit client action to invoke the capability. 1127 Client and server implementations MUST implement the STARTTLS, 1128 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1129 See the Security Considerations section for important information. 1131 See the section entitled "Client Commands - Experimental/Expansion" 1132 for information about the form of site or implementation-specific 1133 capabilities. 1135 Example: C: abcd CAPABILITY 1136 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1137 LOGINDISABLED 1138 S: abcd OK CAPABILITY completed 1139 C: efgh STARTTLS 1140 S: efgh OK STARTLS completed 1141 1142 C: ijkl CAPABILITY 1143 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1144 S: ijkl OK CAPABILITY completed 1146 6.1.2. NOOP Command 1148 Arguments: none 1150 Responses: no specific responses for this command (but see below) 1152 Result: OK - noop completed 1153 BAD - command unknown or arguments invalid 1155 The NOOP command always succeeds. It does nothing. 1157 Since any command can return a status update as untagged data, the 1158 NOOP command can be used as a periodic poll for new messages or 1159 message status updates during a period of inactivity (the IDLE 1160 command Section 6.3.13 should be used instead of NOOP if real-time 1161 updates to mailbox state are desirable). The NOOP command can also 1162 be used to reset any inactivity autologout timer on the server. 1164 Example: C: a002 NOOP 1165 S: a002 OK NOOP completed 1166 . . . 1167 C: a047 NOOP 1168 S: * 22 EXPUNGE 1169 S: * 23 EXISTS 1170 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1171 S: a047 OK NOOP completed 1173 6.1.3. LOGOUT Command 1175 Arguments: none 1177 Responses: REQUIRED untagged response: BYE 1179 Result: OK - logout completed 1180 BAD - command unknown or arguments invalid 1182 The LOGOUT command informs the server that the client is done with 1183 the connection. The server MUST send a BYE untagged response before 1184 the (tagged) OK response, and then close the network connection. 1186 Example: C: A023 LOGOUT 1187 S: * BYE IMAP4rev2 Server logging out 1188 S: A023 OK LOGOUT completed 1189 (Server and client then close the connection) 1191 6.2. Client Commands - Not Authenticated State 1193 In the not authenticated state, the AUTHENTICATE or LOGIN command 1194 establishes authentication and enters the authenticated state. The 1195 AUTHENTICATE command provides a general mechanism for a variety of 1196 authentication techniques, privacy protection, and integrity 1197 checking; whereas the LOGIN command uses a traditional user name and 1198 plaintext password pair and has no means of establishing privacy 1199 protection or integrity checking. 1201 The STARTTLS command is an alternate form of establishing session 1202 privacy protection and integrity checking, but does not by itself 1203 establish authentication or enter the authenticated state. 1205 Server implementations MAY allow access to certain mailboxes without 1206 establishing authentication. This can be done by means of the 1207 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1208 convention is a LOGIN command using the userid "anonymous"; in this 1209 case, a password is required although the server may choose to accept 1210 any password. The restrictions placed on anonymous users are 1211 implementation-dependent. 1213 Once authenticated (including as anonymous), it is not possible to 1214 re-enter not authenticated state. 1216 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1217 the following commands are valid in the not authenticated state: 1218 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1219 section for important information about these commands. 1221 6.2.1. STARTTLS Command 1223 Arguments: none 1225 Responses: no specific response for this command 1227 Result: OK - starttls completed, begin TLS negotiation 1228 BAD - command unknown or arguments invalid 1230 A [TLS] negotiation begins immediately after the CRLF at the end of 1231 the tagged OK response from the server. Once a client issues a 1232 STARTTLS command, it MUST NOT issue further commands until a server 1233 response is seen and the [TLS] negotiation is complete. 1235 The server remains in the non-authenticated state, even if client 1236 credentials are supplied during the [TLS] negotiation. This does not 1237 preclude an authentication mechanism such as EXTERNAL (defined in 1238 [SASL]) from using client identity determined by the [TLS] 1239 negotiation. 1241 Once [TLS] has been started, the client MUST discard cached 1242 information about server capabilities and SHOULD re-issue the 1243 CAPABILITY command. This is necessary to protect against man-in- 1244 the-middle attacks which alter the capabilities list prior to 1245 STARTTLS. The server MAY advertise different capabilities, and in 1246 particular SHOULD NOT advertise the STARTTLS capability, after a 1247 successful STARTTLS command. 1249 Example: C: a001 CAPABILITY 1250 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1251 S: a001 OK CAPABILITY completed 1252 C: a002 STARTTLS 1253 S: a002 OK Begin TLS negotiation now 1254 1255 C: a003 CAPABILITY 1256 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1257 S: a003 OK CAPABILITY completed 1258 C: a004 LOGIN joe password 1259 S: a004 OK LOGIN completed 1261 6.2.2. AUTHENTICATE Command 1263 Arguments: SASL authentication mechanism name 1264 OPTIONAL initial response 1266 Responses: continuation data can be requested 1268 Result: OK - authenticate completed, now in authenticated state 1269 NO - authenticate failure: unsupported authentication 1270 mechanism, credentials rejected 1271 BAD - command unknown or arguments invalid, 1272 authentication exchange cancelled 1274 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1275 to the server. If the server supports the requested authentication 1276 mechanism, it performs an authentication protocol exchange to 1277 authenticate and identify the client. It MAY also negotiate an 1278 OPTIONAL security layer for subsequent protocol interactions. If the 1279 requested authentication mechanism is not supported, the server 1280 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1281 response. 1283 The AUTHENTICATE command supports the optional "initial response" 1284 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1285 use it. If a SASL mechanism supports "initial response", but it is 1286 not specified by the client, the server handles this as specified in 1287 Section 3 of [SASL]. 1289 The service name specified by this protocol's profile of [SASL] is 1290 "imap". 1292 The authentication protocol exchange consists of a series of server 1293 challenges and client responses that are specific to the 1294 authentication mechanism. A server challenge consists of a command 1295 continuation request response with the "+" token followed by a BASE64 1296 encoded (see Section 4 of [RFC4648]) string. The client response 1297 consists of a single line consisting of a BASE64 encoded string. If 1298 the client wishes to cancel an authentication exchange, it issues a 1299 line consisting of a single "*". If the server receives such a 1300 response, or if it receives an invalid BASE64 string (e.g. 1301 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1302 reject the AUTHENTICATE command by sending a tagged BAD response. 1304 As with any other client response, this initial response MUST be 1305 encoded as BASE64. It also MUST be transmitted outside of a quoted 1306 string or literal. To send a zero-length initial response, the 1307 client MUST send a single pad character ("="). This indicates that 1308 the response is present, but is a zero-length string. 1310 When decoding the BASE64 data in the initial response, decoding 1311 errors MUST be treated as in any normal SASL client response, i.e. 1312 with a tagged BAD response. In particular, the server should check 1313 for any characters not explicitly allowed by the BASE64 alphabet, as 1314 well as any sequence of BASE64 characters that contains the pad 1315 character ('=') anywhere other than the end of the string (e.g., 1316 "=AAA" and "AAA=BBB" are not allowed). 1318 If the client uses an initial response with a SASL mechanism that 1319 does not support an initial response, the server MUST reject the 1320 command with a tagged BAD response. 1322 If a security layer is negotiated through the [SASL] authentication 1323 exchange, it takes effect immediately following the CRLF that 1324 concludes the authentication exchange for the client, and the CRLF of 1325 the tagged OK response for the server. 1327 While client and server implementations MUST implement the 1328 AUTHENTICATE command itself, it is not required to implement any 1329 authentication mechanisms other than the PLAIN mechanism described in 1330 [PLAIN]. Also, an authentication mechanism is not required to 1331 support any security layers. 1333 Note: a server implementation MUST implement a configuration in 1334 which it does NOT permit any plaintext password mechanisms, unless 1335 either the STARTTLS command has been negotiated or some other 1336 mechanism that protects the session from password snooping has 1337 been provided. Server sites SHOULD NOT use any configuration 1338 which permits a plaintext password mechanism without such a 1339 protection mechanism against password snooping. Client and server 1340 implementations SHOULD implement additional [SASL] mechanisms that 1341 do not use plaintext passwords, such the GSSAPI mechanism 1342 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1343 [SCRAM-SHA-256] mechanisms. 1345 Servers and clients can support multiple authentication mechanisms. 1346 The server SHOULD list its supported authentication mechanisms in the 1347 response to the CAPABILITY command so that the client knows which 1348 authentication mechanisms to use. 1350 A server MAY include a CAPABILITY response code in the tagged OK 1351 response of a successful AUTHENTICATE command in order to send 1352 capabilities automatically. It is unnecessary for a client to send a 1353 separate CAPABILITY command if it recognizes these automatic 1354 capabilities. This should only be done if a security layer was not 1355 negotiated by the AUTHENTICATE command, because the tagged OK 1356 response as part of an AUTHENTICATE command is not protected by 1357 encryption/integrity checking. [SASL] requires the client to re- 1358 issue a CAPABILITY command in this case. The server MAY advertise 1359 different capabilities after a successful AUTHENTICATE command. 1361 If an AUTHENTICATE command fails with a NO response, the client MAY 1362 try another authentication mechanism by issuing another AUTHENTICATE 1363 command. It MAY also attempt to authenticate by using the LOGIN 1364 command (see Section 6.2.3 for more detail). In other words, the 1365 client MAY request authentication types in decreasing order of 1366 preference, with the LOGIN command as a last resort. 1368 The authorization identity passed from the client to the server 1369 during the authentication exchange is interpreted by the server as 1370 the user name whose privileges the client is requesting. 1372 Example: S: * OK IMAP4rev2 Server 1373 C: A001 AUTHENTICATE GSSAPI 1374 S: + 1375 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1376 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1377 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1378 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1379 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1380 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1381 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1382 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1383 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1384 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1385 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1386 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1387 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1388 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1389 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1390 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1391 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1392 C: 1393 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1394 ceP2CWY0SR0fAQAgAAQEBAQ= 1395 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1396 wkhbfa2QteAQAgAG1yYwE= 1397 S: A001 OK GSSAPI authentication successful 1399 Note: The line breaks within server challenges and client responses 1400 are for editorial clarity and are not in real authenticators. 1402 6.2.3. LOGIN Command 1404 Arguments: user name 1405 password 1407 Responses: no specific responses for this command 1409 Result: OK - login completed, now in authenticated state 1410 NO - login failure: user name or password rejected 1411 BAD - command unknown or arguments invalid 1413 The LOGIN command identifies the client to the server and carries the 1414 plaintext password authenticating this user. 1416 A server MAY include a CAPABILITY response code in the tagged OK 1417 response to a successful LOGIN command in order to send capabilities 1418 automatically. It is unnecessary for a client to send a separate 1419 CAPABILITY command if it recognizes these automatic capabilities. 1421 Example: C: a001 LOGIN SMITH SESAME 1422 S: a001 OK LOGIN completed 1424 Note: Use of the LOGIN command over an insecure network (such as the 1425 Internet) is a security risk, because anyone monitoring network 1426 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1427 be used except as a last resort, and it is recommended that client 1428 implementations have a means to disable any automatic use of the 1429 LOGIN command. 1431 Unless either the client is accessing IMAP service on IMAPS port 1432 [RFC8314], the STARTTLS command has been negotiated or some other 1433 mechanism that protects the session from password snooping has been 1434 provided, a server implementation MUST implement a configuration in 1435 which it advertises the LOGINDISABLED capability and does NOT permit 1436 the LOGIN command. Server sites SHOULD NOT use any configuration 1437 which permits the LOGIN command without such a protection mechanism 1438 against password snooping. A client implementation MUST NOT send a 1439 LOGIN command if the LOGINDISABLED capability is advertised. 1441 6.3. Client Commands - Authenticated State 1443 In the authenticated state, commands that manipulate mailboxes as 1444 atomic entities are permitted. Of these commands, the SELECT and 1445 EXAMINE commands will select a mailbox for access and enter the 1446 selected state. 1448 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1449 the following commands are valid in the authenticated state: ENABLE, 1450 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1451 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1453 6.3.1. ENABLE Command 1455 Arguments: capability names 1457 Responses: no specific responses for this command 1459 Result: OK - Relevant capabilities enabled 1460 BAD - No arguments, or syntax error in an argument 1462 Several IMAP extensions allow the server to return unsolicited 1463 responses specific to these extensions in certain circumstances. 1464 However, servers cannot send those unsolicited responses (with the 1465 exception of response codes (see Section 7.1) included in tagged or 1466 untagged OK/NO/BAD responses, which can always be sent) until they 1467 know that the clients support such extensions and thus won't choke on 1468 the extension response data. 1470 The ENABLE command provides an explicit indication from the client 1471 that it supports particular extensions. It is designed such that the 1472 client can send a simple constant string with the extensions it 1473 supports, and the server will enable the shared subset that both 1474 support. 1476 The ENABLE command takes a list of capability names, and requests the 1477 server to enable the named extensions. Once enabled using ENABLE, 1478 each extension remains active until the IMAP connection is closed. 1479 For each argument, the server does the following: 1481 o If the argument is not an extension known to the server, the 1482 server MUST ignore the argument. 1484 o If the argument is an extension known to the server, and it is not 1485 specifically permitted to be enabled using ENABLE, the server MUST 1486 ignore the argument. (Note that knowing about an extension 1487 doesn't necessarily imply supporting that extension.) 1489 o If the argument is an extension that is supported by the server 1490 and that needs to be enabled, the server MUST enable the extension 1491 for the duration of the connection. Note that once an extension 1492 is enabled, there is no way to disable it. 1494 If the ENABLE command is successful, the server MUST send an untagged 1495 ENABLED response Section 7.2.1. 1497 Clients SHOULD only include extensions that need to be enabled by the 1498 server. For example, a client can enable IMAP4rev2 specific 1499 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1500 CAPABILITY response. Future RFCs may add to this list. 1502 The ENABLE command is only valid in the authenticated state, before 1503 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1504 SELECT/EXAMINE a mailbox; however, server implementations don't have 1505 to check that no mailbox is selected or was previously selected 1506 during the duration of a connection. 1508 The ENABLE command can be issued multiple times in a session. It is 1509 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1510 single command "ENABLE a b c". When multiple ENABLE commands are 1511 issued, each corresponding ENABLED response SHOULD only contain 1512 extensions enabled by the corresponding ENABLE command. 1514 There are no limitations on pipelining ENABLE. For example, it is 1515 possible to send ENABLE and then immediately SELECT, or a LOGIN 1516 immediately followed by ENABLE. 1518 The server MUST NOT change the CAPABILITY list as a result of 1519 executing ENABLE; i.e., a CAPABILITY command issued right after an 1520 ENABLE command MUST list the same capabilities as a CAPABILITY 1521 command issued before the ENABLE command. This is demonstrated in 1522 the following example: 1524 C: t1 CAPABILITY 1525 S: * CAPABILITY IMAP4rev1 ID LITERAL+ ENABLE X-GOOD-IDEA 1526 S: t1 OK foo 1527 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1528 S: * ENABLED X-GOOD-IDEA 1529 S: t2 OK foo 1530 C: t3 CAPABILITY 1531 S: * CAPABILITY IMAP4rev1 ID LITERAL+ ENABLE X-GOOD-IDEA 1532 S: t3 OK foo again 1534 In the following example, the client enables CONDSTORE: 1536 C: a1 ENABLE CONDSTORE 1537 S: * ENABLED CONDSTORE 1538 S: a1 OK Conditional Store enabled 1540 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1541 Command 1543 Designers of IMAP extensions are discouraged from creating extensions 1544 that require ENABLE unless there is no good alternative design. 1545 Specifically, extensions that cause potentially incompatible behavior 1546 changes to deployed server responses (and thus benefit from ENABLE) 1547 have a higher complexity cost than extensions that do not. 1549 6.3.2. SELECT Command 1551 Arguments: mailbox name 1553 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1554 REQUIRED OK untagged responses: PERMANENTFLAGS, 1555 UIDNEXT, UIDVALIDITY 1557 Result: OK - select completed, now in selected state 1558 NO - select failure, now in authenticated state: no 1559 such mailbox, can't access mailbox 1560 BAD - command unknown or arguments invalid 1562 The SELECT command selects a mailbox so that messages in the mailbox 1563 can be accessed. Before returning an OK to the client, the server 1564 MUST send the following untagged data to the client. Note that 1565 earlier versions of this protocol only required the FLAGS and EXISTS 1566 untagged data; consequently, client implementations SHOULD implement 1567 default behavior for missing data as discussed with the individual 1568 item. 1570 FLAGS Defined flags in the mailbox. See the description of the 1571 FLAGS response for more detail. 1573 EXISTS The number of messages in the mailbox. See the 1574 description of the EXISTS response for more detail. 1576 OK [PERMANENTFLAGS ()] A list of message flags that 1577 the client can change permanently. If this is missing, the client 1578 should assume that all flags can be changed permanently. 1580 OK [UIDNEXT ] The next unique identifier value. Refer to 1581 Section 2.3.1.1 for more information. 1583 OK [UIDNEXT ] If this is missing, the client can not make any 1584 assumptions about the next unique identifier value. 1586 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1587 Section 2.3.1.1 for more information. If this is missing, the 1588 server does not support unique identifiers. 1590 Only one mailbox can be selected at a time in a connection; 1591 simultaneous access to multiple mailboxes requires multiple 1592 connections. The SELECT command automatically deselects any 1593 currently selected mailbox before attempting the new selection. 1594 Consequently, if a mailbox is selected and a SELECT command that 1595 fails is attempted, no mailbox is selected. When deselecting a 1596 selected mailbox, the server MUST return an untagged OK response with 1597 the "[CLOSED]" response code when the currently selected mailbox is 1598 closed (see Paragraph 10). 1600 If the client is permitted to modify the mailbox, the server SHOULD 1601 prefix the text of the tagged OK response with the "[READ-WRITE]" 1602 response code. 1604 If the client is not permitted to modify the mailbox but is permitted 1605 read access, the mailbox is selected as read-only, and the server 1606 MUST prefix the text of the tagged OK response to SELECT with the 1607 "[READ-ONLY]" response code. Read-only access through SELECT differs 1608 from the EXAMINE command in that certain read-only mailboxes MAY 1609 permit the change of permanent state on a per-user (as opposed to 1610 global) basis. Netnews messages marked in a server-based .newsrc 1611 file are an example of such per-user permanent state that can be 1612 modified with read-only mailboxes. 1614 Example: C: A142 SELECT INBOX 1615 S: * 172 EXISTS 1616 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1617 S: * OK [UIDNEXT 4392] Predicted next UID 1618 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1619 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1620 S: A142 OK [READ-WRITE] SELECT completed 1622 Example: C: A142 SELECT INBOX 1623 S: * 172 EXISTS 1624 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1625 S: * OK [UIDNEXT 4392] Predicted next UID 1626 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1627 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1628 S: A142 OK [READ-WRITE] SELECT completed 1629 [...some time later...] 1630 C: A143 SELECT Drafts 1631 S: * OK [CLOSED] Previous mailbox is now closed 1632 S: * 5 EXISTS 1633 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1634 S: * OK [UIDNEXT 102] Predicted next UID 1635 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1636 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1637 \Flagged \Draft \*)] System flags and keywords allowed 1638 S: A143 OK [READ-WRITE] SELECT completed 1640 Note that IMAP4rev1 compliant servers can also send the untagged 1641 RECENT response which was depractated in IMAP4rev2. E.g. "* 0 1642 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1643 RECENT response. 1645 6.3.3. EXAMINE Command 1647 Arguments: mailbox name 1649 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1650 REQUIRED OK untagged responses: PERMANENTFLAGS, 1651 UIDNEXT, UIDVALIDITY 1653 Result: OK - examine completed, now in selected state 1654 NO - examine failure, now in authenticated state: no 1655 such mailbox, can't access mailbox BAD - command unknown 1656 or arguments invalid 1658 The EXAMINE command is identical to SELECT and returns the same 1659 output; however, the selected mailbox is identified as read-only. No 1660 changes to the permanent state of the mailbox, including per-user 1661 state, are permitted. 1663 The text of the tagged OK response to the EXAMINE command MUST begin 1664 with the "[READ-ONLY]" response code. 1666 Example: C: A932 EXAMINE blurdybloop 1667 S: * 17 EXISTS 1668 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1669 S: * OK [UIDNEXT 4392] Predicted next UID 1670 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1671 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1672 S: A932 OK [READ-ONLY] EXAMINE completed 1674 6.3.4. CREATE Command 1676 Arguments: mailbox name 1678 Responses: no specific responses for this command 1680 Result: OK - create completed 1681 NO - create failure: can't create mailbox with that name 1682 BAD - command unknown or arguments invalid 1684 The CREATE command creates a mailbox with the given name. An OK 1685 response is returned only if a new mailbox with that name has been 1686 created. It is an error to attempt to create INBOX or a mailbox with 1687 a name that refers to an extant mailbox. Any error in creation will 1688 return a tagged NO response. If a client attempts to create a UTF-8 1689 mailbox name that is not a valid Net-Unicode name, the server MUST 1690 reject the creation or convert the name to Net-Unicode prior to 1691 creating the mailbox. 1693 If the mailbox name is suffixed with the server's hierarchy separator 1694 character (as returned from the server by a LIST command), this is a 1695 declaration that the client intends to create mailbox names under 1696 this name in the hierarchy. Server implementations that do not 1697 require this declaration MUST ignore the declaration. In any case, 1698 the name created is without the trailing hierarchy delimiter. 1700 If the server's hierarchy separator character appears elsewhere in 1701 the name, the server SHOULD create any superior hierarchical names 1702 that are needed for the CREATE command to be successfully completed. 1703 In other words, an attempt to create "foo/bar/zap" on a server in 1704 which "/" is the hierarchy separator character SHOULD create foo/ and 1705 foo/bar/ if they do not already exist. 1707 If a new mailbox is created with the same name as a mailbox which was 1708 deleted, its unique identifiers MUST be greater than any unique 1709 identifiers used in the previous incarnation of the mailbox UNLESS 1710 the new incarnation has a different unique identifier validity value. 1711 See the description of the UID command for more detail. 1713 Example: C: A003 CREATE owatagusiam/ 1714 S: A003 OK CREATE completed 1715 C: A004 CREATE owatagusiam/blurdybloop 1716 S: A004 OK CREATE completed 1718 Note: The interpretation of this example depends on whether "/" 1719 was returned as the hierarchy separator from LIST. If "/" is the 1720 hierarchy separator, a new level of hierarchy named "owatagusiam" 1721 with a member called "blurdybloop" is created. Otherwise, two 1722 mailboxes at the same hierarchy level are created. 1724 6.3.5. DELETE Command 1726 Arguments: mailbox name 1728 Responses: no specific responses for this command 1730 Result: OK - delete completed 1731 NO - delete failure: can't delete mailbox with that name 1732 BAD - command unknown or arguments invalid 1734 The DELETE command permanently removes the mailbox with the given 1735 name. A tagged OK response is returned only if the mailbox has been 1736 deleted. It is an error to attempt to delete INBOX or a mailbox name 1737 that does not exist. 1739 The DELETE command MUST NOT remove inferior hierarchical names. For 1740 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1741 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1742 "foo.bar". It is an error to attempt to delete a name that has 1743 inferior hierarchical names and also has the \Noselect mailbox name 1744 attribute (see the description of the LIST response for more 1745 details). 1747 It is permitted to delete a name that has inferior hierarchical names 1748 and does not have the \Noselect mailbox name attribute. If the 1749 server implementation does not permit deleting the name while 1750 inferior hierarchical names exists the \Noselect mailbox name 1751 attribute is set for that name. In any case, all messages in that 1752 mailbox are removed by the DELETE command. 1754 The value of the highest-used unique identifier of the deleted 1755 mailbox MUST be preserved so that a new mailbox created with the same 1756 name will not reuse the identifiers of the former incarnation, UNLESS 1757 the new incarnation has a different unique identifier validity value. 1758 See the description of the UID command for more detail. 1760 Examples: C: A682 LIST "" * 1761 S: * LIST () "/" blurdybloop 1762 S: * LIST (\Noselect) "/" foo 1763 S: * LIST () "/" foo/bar 1764 S: A682 OK LIST completed 1765 C: A683 DELETE blurdybloop 1766 S: A683 OK DELETE completed 1767 C: A684 DELETE foo 1768 S: A684 NO Name "foo" has inferior hierarchical names 1769 C: A685 DELETE foo/bar 1770 S: A685 OK DELETE Completed 1771 C: A686 LIST "" * 1772 S: * LIST (\Noselect) "/" foo 1773 S: A686 OK LIST completed 1774 C: A687 DELETE foo 1775 S: A687 OK DELETE Completed 1776 C: A82 LIST "" * 1777 S: * LIST () "." blurdybloop 1778 S: * LIST () "." foo 1779 S: * LIST () "." foo.bar 1780 S: A82 OK LIST completed 1781 C: A83 DELETE blurdybloop 1782 S: A83 OK DELETE completed 1783 C: A84 DELETE foo 1784 S: A84 OK DELETE Completed 1785 C: A85 LIST "" * 1786 S: * LIST () "." foo.bar 1787 S: A85 OK LIST completed 1788 C: A86 LIST "" % 1789 S: * LIST (\Noselect) "." foo 1790 S: A86 OK LIST completed 1792 6.3.6. RENAME Command 1794 Arguments: existing mailbox name 1795 new mailbox name 1797 Responses: no specific responses for this command 1799 Result: OK - rename completed 1800 NO - rename failure: can't rename mailbox with that name, 1801 can't rename to mailbox with that name 1802 BAD - command unknown or arguments invalid 1804 The RENAME command changes the name of a mailbox. A tagged OK 1805 response is returned only if the mailbox has been renamed. It is an 1806 error to attempt to rename from a mailbox name that does not exist or 1807 to a mailbox name that already exists. Any error in renaming will 1808 return a tagged NO response. 1810 If the name has inferior hierarchical names, then the inferior 1811 hierarchical names MUST also be renamed. For example, a rename of 1812 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1813 delimiter character) to "zap/bar". 1815 If the server's hierarchy separator character appears in the name, 1816 the server SHOULD create any superior hierarchical names that are 1817 needed for the RENAME command to complete successfully. In other 1818 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1820 server in which "/" is the hierarchy separator character SHOULD 1821 create baz/ and baz/rag/ if they do not already exist. 1823 The value of the highest-used unique identifier of the old mailbox 1824 name MUST be preserved so that a new mailbox created with the same 1825 name will not reuse the identifiers of the former incarnation, UNLESS 1826 the new incarnation has a different unique identifier validity value. 1827 See the description of the UID command for more detail. 1829 Renaming INBOX is permitted, and has special behavior. (Note that 1830 some servers refuse renaming INBOX). It moves all messages in INBOX 1831 to a new mailbox with the given name, leaving INBOX empty. If the 1832 server implementation supports inferior hierarchical names of INBOX, 1833 these are unaffected by a rename of INBOX. 1835 Examples: C: A682 LIST "" * 1836 S: * LIST () "/" blurdybloop 1837 S: * LIST (\Noselect) "/" foo 1838 S: * LIST () "/" foo/bar 1839 S: A682 OK LIST completed 1840 C: A683 RENAME blurdybloop sarasoop 1841 S: A683 OK RENAME completed 1842 C: A684 RENAME foo zowie 1843 S: A684 OK RENAME Completed 1844 C: A685 LIST "" * 1845 S: * LIST () "/" sarasoop 1846 S: * LIST (\Noselect) "/" zowie 1847 S: * LIST () "/" zowie/bar 1848 S: A685 OK LIST completed 1850 C: Z432 LIST "" * 1851 S: * LIST () "." INBOX 1852 S: * LIST () "." INBOX.bar 1853 S: Z432 OK LIST completed 1854 C: Z433 RENAME INBOX old-mail 1855 S: Z433 OK RENAME completed 1856 C: Z434 LIST "" * 1857 S: * LIST () "." INBOX 1858 S: * LIST () "." INBOX.bar 1859 S: * LIST () "." old-mail 1860 S: Z434 OK LIST completed 1862 Note that renaming a mailbox doesn't update subscription information 1863 on the original name. To keep subscription information in sync, the 1864 following sequence of commands can be used: 1866 C: 1001 RENAME X Y 1867 C: 1002 SUBSCRIBE Y 1868 C: 1003 UNSUBSCRIBE X 1870 Note that the above sequence of commands doesn't account for updating 1871 subscription for any children mailboxes of mailbox X. 1873 6.3.7. SUBSCRIBE Command 1875 Arguments: mailbox 1877 Responses: no specific responses for this command 1879 Result: OK - subscribe completed 1880 NO - subscribe failure: can't subscribe to that name 1881 BAD - command unknown or arguments invalid 1883 The SUBSCRIBE command adds the specified mailbox name to the server's 1884 set of "active" or "subscribed" mailboxes as returned by the LIST 1885 (SUBSCRIBED) command. This command returns a tagged OK response only 1886 if the subscription is successful. 1888 A server MAY validate the mailbox argument to SUBSCRIBE to verify 1889 that it exists. However, it MUST NOT unilaterally remove an existing 1890 mailbox name from the subscription list even if a mailbox by that 1891 name no longer exists. 1893 Note: This requirement is because a server site can choose to 1894 routinely remove a mailbox with a well-known name (e.g., "system- 1895 alerts") after its contents expire, with the intention of 1896 recreating it when new contents are appropriate. 1898 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 1899 S: A002 OK SUBSCRIBE completed 1901 6.3.8. UNSUBSCRIBE Command 1903 Arguments: mailbox name 1905 Responses: no specific responses for this command 1907 Result: OK - unsubscribe completed 1908 NO - unsubscribe failure: can't unsubscribe that name 1909 BAD - command unknown or arguments invalid 1911 The UNSUBSCRIBE command removes the specified mailbox name from the 1912 server's set of "active" or "subscribed" mailboxes as returned by the 1913 LIST (SUBSCRIBED) command. This command returns a tagged OK response 1914 only if the unsubscription is successful. 1916 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 1917 S: A002 OK UNSUBSCRIBE completed 1919 6.3.9. LIST Command 1921 Arguments (basic): reference name 1922 mailbox name with possible wildcards 1924 Arguments (extended): selection options (OPTIONAL) 1925 reference name 1926 mailbox patterns 1927 return options (OPTIONAL) 1929 Responses: untagged responses: LIST 1930 Result: OK - list completed 1931 NO - list failure: can't list that reference or name 1932 BAD - command unknown or arguments invalid 1934 The LIST command returns a subset of names from the complete set of 1935 all names available to the client. Zero or more untagged LIST 1936 replies are returned, containing the name attributes, hierarchy 1937 delimiter, name, and possible extension information; see the 1938 description of the LIST reply for more detail. 1940 The LIST command SHOULD return its data quickly, without undue delay. 1941 For example, it SHOULD NOT go to excess trouble to calculate the 1942 \Marked or \Unmarked status or perform other processing; if each name 1943 requires 1 second of processing, then a list of 1200 names would take 1944 20 minutes! 1946 The extended LIST command, originally introduced in [RFC5258], 1947 provides capabilities beyond that of the original IMAP LIST command. 1948 The extended syntax is being used if one or more of the following 1949 conditions is true: 1951 1. if the first word after the command name begins with a 1952 parenthesis ("LIST selection options") 1954 2. if the second word after the command name begins with a 1955 parenthesis ("multiple mailbox patterns") 1957 3. if the LIST command has more than 2 parameters ("LIST return 1958 options") 1960 An empty ("" string) reference name argument indicates that the 1961 mailbox name is interpreted as by SELECT. The returned mailbox names 1962 MUST match the supplied mailbox name pattern(s). A non-empty 1963 reference name argument is the name of a mailbox or a level of 1964 mailbox hierarchy, and indicates the context in which the mailbox 1965 name is interpreted. Clients SHOULD use the empty reference 1966 argument. 1968 In the basic syntax only, an empty ("" string) mailbox name argument 1969 is a special request to return the hierarchy delimiter and the root 1970 name of the name given in the reference. The value returned as the 1971 root MAY be the empty string if the reference is non-rooted or is an 1972 empty string. In all cases, a hierarchy delimiter (or NIL if there 1973 is no hierarchy) is returned. This permits a client to get the 1974 hierarchy delimiter (or find out that the mailbox names are flat) 1975 even when no mailboxes by that name currently exist. 1977 In the extended syntax, any mailbox name arguments that are empty 1978 strings are ignored. There is no special meaning for empty mailbox 1979 names when the extended syntax is used. 1981 The reference and mailbox name arguments are interpreted into a 1982 canonical form that represents an unambiguous left-to-right 1983 hierarchy. The returned mailbox names will be in the interpreted 1984 form, 1986 that we call "canonical LIST pattern" later in this document. To 1987 define the term "canonical LIST pattern" formally: it refers to the 1988 canonical pattern constructed internally by the server from the 1989 reference and mailbox name arguments. 1991 Note: The interpretation of the reference argument is 1992 implementation-defined. It depends upon whether the server 1993 implementation has a concept of the "current working directory" 1994 and leading "break out characters", which override the current 1995 working directory. 1997 For example, on a server which exports a UNIX or NT filesystem, 1998 the reference argument contains the current working directory, and 1999 the mailbox name argument would contain the name as interpreted in 2000 the current working directory. 2002 If a server implementation has no concept of break out characters, 2003 the canonical form is normally the reference name appended with 2004 the mailbox name. Note that if the server implements the 2005 namespace convention (Section 5.1.2.1), "#" is a break out 2006 character and must be treated as such. 2008 If the reference argument is not a level of mailbox hierarchy 2009 (that is, it is a \NoInferiors name), and/or the reference 2010 argument does not end with the hierarchy delimiter, it is 2011 implementation-dependent how this is interpreted. For example, a 2012 reference of "foo/bar" and mailbox name of "rag/baz" could be 2013 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2014 baz". A client SHOULD NOT use such a reference argument except at 2015 the explicit request of the user. A hierarchical browser MUST NOT 2016 make any assumptions about server interpretation of the reference 2017 unless the reference is a level of mailbox hierarchy AND ends with 2018 the hierarchy delimiter. 2020 Any part of the reference argument that is included in the 2021 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2022 be in the same form as the reference name argument. This rule 2023 permits the client to determine if the returned mailbox name is in 2024 the context of the reference argument, or if something about the 2025 mailbox argument overrode the reference argument. Without this rule, 2026 the client would have to have knowledge of the server's naming 2027 semantics including what characters are "breakouts" that override a 2028 naming context. 2030 For example, here are some examples of how references 2031 and mailbox names might be interpreted on a UNIX-based 2032 server: 2034 Reference Mailbox Name Interpretation 2035 ------------ ------------ -------------- 2036 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2037 archive/ % archive/% 2038 #news. comp.mail.* #news.comp.mail.* 2039 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2040 archive/ ~fred/Mail/* ~fred/Mail/* 2042 The first three examples demonstrate interpretations in 2043 the context of the reference argument. Note that 2044 "~smith/Mail" SHOULD NOT be transformed into something 2045 like "/u2/users/smith/Mail", or it would be impossible 2046 for the client to determine that the interpretation was 2047 in the context of the reference. 2049 The character "*" is a wildcard, and matches zero or more characters 2050 at this position. The character "%" is similar to "*", but it does 2051 not match a hierarchy delimiter. If the "%" wildcard is the last 2052 character of a mailbox name argument, matching levels of hierarchy 2053 are also returned. If these levels of hierarchy are not also 2054 selectable mailboxes, they are returned with the \Noselect mailbox 2055 name attribute (see the description of the LIST response for more 2056 details). 2058 If multiple mailbox patterns are used (in the extended syntax), a 2059 mailbox matches if it matches at least one mailbox pattern. If a 2060 mailbox matches more than one pattern, it is still only returned 2061 once. Any syntactically valid pattern that is not accepted by a 2062 server for any reason MUST be silently ignored. 2064 Selection options tell the server to limit the mailbox names that are 2065 selected by the LIST operation. If selection options are used, the 2066 mailboxes returned are those that match both the list of canonical 2067 LIST patterns and the selection options. Unless a particular 2068 selection option provides special rules, the selection options are 2069 cumulative: a mailbox that matches the mailbox patterns is selected 2070 only if it also matches all of the selection options. (An example of 2071 a selection option with special rules is the RECURSIVEMATCH option.) 2072 Return options control what information is returned for each matched 2073 mailbox. Return options MUST NOT cause the server to report 2074 information about additional mailbox names other than those that 2075 match the canonical LIST patterns and selection options. If no 2076 return options are specified, the client is only expecting 2077 information about mailbox attributes. The server MAY return other 2078 information about the matched mailboxes, and clients MUST be able to 2079 handle that situation. 2081 Initial selection options and return options are defined in the 2082 following subsections, and new ones will also be defined in 2083 extensions. Initial options defined in this document MUST be 2084 supported. Each non-initial option will be enabled by a capability 2085 string (one capability may enable multiple options), and a client 2086 MUST NOT send an option for which the server has not advertised 2087 support. A server MUST respond to options it does not recognize with 2088 a BAD response. The client SHOULD NOT specify any option more than 2089 once; however, if the client does this, the server MUST act as if it 2090 received the option only once. The order in which options are 2091 specified by the client is not significant. 2093 In general, each selection option except RECURSIVEMATCH will have a 2094 corresponding return option. The REMOTE selection option is an 2095 anomaly in this regard, and does not have a corresponding return 2096 option. That is because it expands, rather than restricts, the set 2097 of mailboxes that are returned. Future extensions to this 2098 specification should keep parallelism in mind and define a pair of 2099 corresponding options. 2101 Server implementations are permitted to "hide" otherwise accessible 2102 mailboxes from the wildcard characters, by preventing certain 2103 characters or names from matching a wildcard in certain situations. 2104 For example, a UNIX-based server might restrict the interpretation of 2105 "*" so that an initial "/" character does not match. 2107 The special name INBOX is included in the output from LIST, if INBOX 2108 is supported by this server for this user and if the uppercase string 2109 "INBOX" matches the interpreted reference and mailbox name arguments 2110 with wildcards as described above. The criteria for omitting INBOX 2111 is whether SELECT INBOX will return failure; it is not relevant 2112 whether the user's real INBOX resides on this or some other server. 2114 6.3.9.1. LIST Selection Options 2116 The selection options defined in this specification are as follows: 2118 SUBSCRIBED - causes the LIST command to list subscribed names, 2119 rather than the existing mailboxes. This will often be a subset 2120 of the actual mailboxes. It's also possible for this list to 2121 contain the names of mailboxes that don't exist. In any case, the 2122 list MUST include exactly those mailbox names that match the 2123 canonical list pattern and are subscribed to. 2125 SUBSCRIBED - 2127 This option defines a mailbox attribute, "\Subscribed", that 2128 indicates that a mailbox name is subscribed to. The "\Subscribed" 2129 attribute MUST be supported and MUST be accurately computed when 2130 the SUBSCRIBED selection option is specified. 2132 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2133 return option (see below). 2135 REMOTE - causes the LIST command to show remote mailboxes as well as 2136 local ones, as described in [RFC2193]. This option is intended to 2137 replace the RLIST command and, in conjunction with the SUBSCRIBED 2138 selection option, the RLSUB command. Servers that don't support 2139 remote mailboxes just ignore this option. 2141 This option defines a mailbox attribute, "\Remote", that indicates 2142 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2143 be accurately computed when the REMOTE option is specified. 2145 The REMOTE selection option has no interaction with other options. 2146 Its effect is to tell the server to apply the other options, if 2147 any, to remote mailboxes, in addition to local ones. In 2148 particular, it has no interaction with RECURSIVEMATCH (see below). 2149 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2150 request for (RECURSIVEMATCH) is also invalid. A request for 2151 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2152 mailboxes, both local and remote. 2154 RECURSIVEMATCH - this option forces the server to return information 2155 about parent mailboxes that don't match other selection options, 2156 but have some submailboxes that do. Information about children is 2157 returned in the CHILDINFO extended data item, as described in 2158 Section 6.3.9.6. 2160 Note 1: In order for a parent mailbox to be returned, it still has 2161 to match the canonical LIST pattern. 2163 Note 2: When returning the CHILDINFO extended data item, it 2164 doesn't matter whether or not the submailbox matches the canonical 2165 LIST pattern. See also example 9 in Section 6.3.9.7. 2167 The RECURSIVEMATCH option MUST NOT occur as the only selection 2168 option (or only with REMOTE), as it only makes sense when other 2169 selection options are also used. The server MUST return BAD 2170 tagged response in such case. 2172 Note that even if the RECURSIVEMATCH option is specified, the 2173 client MUST still be able to handle a case when a CHILDINFO 2174 extended data item is returned and there are no submailboxes that 2175 meet the selection criteria of the subsequent LIST command, as 2176 they can be deleted/renamed after the LIST response was sent, but 2177 before the client had a chance to access them. 2179 6.3.9.2. LIST Return Options 2181 The return options defined in this specification are as follows: 2183 SUBSCRIBED - causes the LIST command to return subscription state 2184 for all matching mailbox names. The "\Subscribed" attribute MUST 2185 be supported and MUST be accurately computed when the SUBSCRIBED 2186 return option is specified. Further, all mailbox flags MUST be 2187 accurately computed (this differs from the behavior of the 2188 obsolete LSUB command from IMAP4rev1). 2190 CHILDREN - requests mailbox child information as originally proposed 2191 in [RFC3348]. See Section 6.3.9.5, below, for details. 2193 CHILDREN - This option MUST be supported by all servers. 2195 STATUS - requests STATUS response for each matching mailbox. 2197 This option takes STATUS data items as parameters. For each 2198 selectable mailbox matching the list pattern and selection 2199 options, the server MUST return an untagged LIST response 2200 followed by an untagged STATUS response containing the 2201 information requested in the STATUS return option. 2203 If an attempted STATUS for a listed mailbox fails because the 2204 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2205 is granted to the mailbox and the "r" right is not granted, or 2206 due to a race condition between LIST and STATUS changing the 2207 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2208 and the LIST response MUST include the \NoSelect attribute. 2209 This means the server may have to buffer the LIST reply until 2210 it has successfully looked up the necessary STATUS information. 2212 If the server runs into unexpected problems while trying to 2213 look up the STATUS information, it MAY drop the corresponding 2214 STATUS reply. In such a situation, the LIST command would 2215 still return a tagged OK reply. 2217 6.3.9.3. General Principles for Returning LIST Responses 2219 This section outlines several principles that can be used by server 2220 implementations of this document to decide whether a LIST response 2221 should be returned, as well as how many responses and what kind of 2222 information they may contain. 2224 1. At most one LIST response should be returned for each mailbox 2225 name that matches the canonical LIST pattern. Server 2226 implementors must not assume that clients will be able to 2227 assemble mailbox attributes and other information returned in 2228 multiple LIST responses. 2230 2. There are only two reasons for including a matching mailbox name 2231 in the responses to the LIST command (note that the server is 2232 allowed to return unsolicited responses at any time, and such 2233 responses are not governed by this rule): 2235 A. The mailbox name also satisfies the selection criteria. 2237 B. The mailbox name doesn't satisfy the selection criteria, but 2238 it has at least one descendant mailbox name that satisfies 2239 the selection criteria and that doesn't match the canonical 2240 LIST pattern. 2242 For more information on this case, see the CHILDINFO extended 2243 data item described in Section 6.3.9.6. Note that the 2244 CHILDINFO extended data item can only be returned when the 2245 RECURSIVEMATCH selection option is specified. 2247 3. Attributes returned in the same LIST response must be treated 2248 additively. For example, the following response 2250 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2252 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2253 subscribed. 2255 6.3.9.4. Additional LIST-related Requirements on Clients 2257 All clients MUST treat a LIST attribute with a stronger meaning as 2258 implying any attribute that can be inferred from it. (See 2259 Section 7.2.3 for the list of currently defined attributes). For 2260 example, the client must treat the presence of the \NoInferiors 2261 attribute as if the \HasNoChildren attribute was also sent by the 2262 server. 2264 The following table summarizes inference rules. 2266 +--------------------+-------------------+ 2267 | returned attribute | implied attribute | 2268 +--------------------+-------------------+ 2269 | \NoInferiors | \HasNoChildren | 2270 | \NonExistent | \NoSelect | 2271 +--------------------+-------------------+ 2273 6.3.9.5. The CHILDREN Return Option 2275 The CHILDREN return option implements the Child Mailbox Extension, 2276 originally proposed by Mike Gahrns and Raymond Cheng, of Microsoft 2277 Corporation. Most of the information in this section is taken 2278 directly from their original specification [RFC3348]. The CHILDREN 2279 return option is simply an indication that the client wants this 2280 information; a server MAY provide it even if the option is not 2281 specified. 2283 Many IMAP4 clients present to the user a hierarchical view of the 2284 mailboxes that a user has access to. Rather than initially 2285 presenting to the user the entire mailbox hierarchy, it is often 2286 preferable to show to the user a collapsed outline list of the 2287 mailbox hierarchy (particularly if there is a large number of 2288 mailboxes). The user can then expand the collapsed outline hierarchy 2289 as needed. It is common to include within the collapsed hierarchy a 2290 visual clue (such as a ''+'') to indicate that there are child 2291 mailboxes under a particular mailbox. When the visual clue is 2292 clicked, the hierarchy list is expanded to show the child mailboxes. 2293 The CHILDREN return option provides a mechanism for a client to 2294 efficiently determine whether a particular mailbox has children, 2295 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2296 The CHILDREN return option defines two new attributes that MUST be 2297 returned within a LIST response: \HasChildren and \HasNoChildren. 2298 Although these attributes MAY be returned in response to any LIST 2299 command, the CHILDREN return option is provided to indicate that the 2300 client particularly wants this information. If the CHILDREN return 2301 option is present, the server MUST return these attributes even if 2302 their computation is expensive. 2304 \HasChildren 2306 The presence of this attribute indicates that the mailbox has 2307 child mailboxes. A server SHOULD NOT set this attribute if 2308 there are child mailboxes and the user does not have permission 2309 to access any of them. In this case, \HasNoChildren SHOULD be 2310 used. In many cases, however, a server may not be able to 2311 efficiently compute whether a user has access to any child 2312 mailbox. Note that even though the \HasChildren attribute for a 2313 mailbox must be correct at the time of processing of the 2314 mailbox, a client must be prepared to deal with a situation when 2315 a mailbox is marked with the \HasChildren attribute, but no 2316 child mailbox appears in the response to the LIST command. This 2317 might happen, for example, due to children mailboxes being 2318 deleted or made inaccessible to the user (using access control) 2319 by another client before the server is able to list them. 2321 \HasNoChildren 2323 The presence of this attribute indicates that the mailbox has NO 2324 child mailboxes that are accessible to the currently 2325 authenticated user. 2327 It is an error for the server to return both a \HasChildren and a 2328 \HasNoChildren attribute in the same LIST response. 2330 Note: the \HasNoChildren attribute should not be confused with the 2331 the \NoInferiors attribute, which indicates that no child mailboxes 2332 exist now and none can be created in the future. 2334 6.3.9.6. CHILDINFO Extended Data Item 2336 The CHILDINFO extended data item MUST NOT be returned unless the 2337 client has specified the RECURSIVEMATCH selection option. 2339 The CHILDINFO extended data item in a LIST response describes the 2340 selection criteria that has caused it to be returned and indicates 2341 that the mailbox has at least one descendant mailbox that matches the 2342 selection criteria. 2344 Note: Some servers allow for mailboxes to exist without requiring 2345 their parent to exist. For example, a mailbox "Customers/ABC" can 2346 exist while the mailbox "Customers" does not. As CHILDINFO extended 2347 data item is not allowed if the RECURSIVEMATCH selection option is 2348 not specified, such servers SHOULD use the "\NonExistent 2349 \HasChildren" attribute pair to signal to the client that there is a 2350 descendant mailbox that matches the selection criteria. See example 2351 11 in Section 6.3.9.7. 2353 The returned selection criteria allow the client to distinguish a 2354 solicited response from an unsolicited one, as well as to distinguish 2355 among solicited responses caused by multiple pipelined LIST commands 2356 that specify different criteria. 2358 Servers SHOULD ONLY return a non-matching mailbox name along with 2359 CHILDINFO if at least one matching child is not also being returned. 2360 That is, servers SHOULD suppress redundant CHILDINFO responses. 2362 Examples 8 and 10 in Section 6.3.9.7 demonstrate the difference 2363 between present CHILDINFO extended data item and the "\HasChildren" 2364 attribute. 2366 The following table summarizes interaction between the "\NonExistent" 2367 attribute and CHILDINFO (the first column indicates whether the 2368 parent mailbox exists): 2370 +--------+--------------+--------------------+----------------------+ 2371 | exists | meets the | has a child that | returned LIST- | 2372 | | selection | meets the | EXTENDED attributes | 2373 | | criteria | selection criteria | and CHILDINFO | 2374 +--------+--------------+--------------------+----------------------+ 2375 | no | no | no | no LIST response | 2376 | | | | returned | 2377 | yes | no | no | no LIST response | 2378 | | | | returned | 2379 | no | yes | no | (\NonExistent | 2380 | | | | ) | 2381 | yes | yes | no | () | 2382 | no | no | yes | (\NonExistent) + | 2383 | | | | CHILDINFO | 2384 | yes | no | yes | () + CHILDINFO | 2385 | no | yes | yes | (\NonExistent | 2386 | | | | ) + CHILDINFO | 2387 | yes | yes | yes | () + CHILDINFO | 2388 +--------+--------------+--------------------+----------------------+ 2390 where is one or more attributes that correspond to the 2391 selection criteria; for example, for the SUBSCRIBED option the 2392 is \Subscribed. 2394 6.3.9.7. LIST Command Examples 2396 This example shows some uses of the basic LIST command: 2398 Example: C: A101 LIST "" "" 2399 S: * LIST (\Noselect) "/" "" 2400 S: A101 OK LIST Completed 2401 C: A102 LIST #news.comp.mail.misc "" 2402 S: * LIST (\Noselect) "." #news. 2403 S: A102 OK LIST Completed 2404 C: A103 LIST /usr/staff/jones "" 2405 S: * LIST (\Noselect) "/" / 2406 S: A103 OK LIST Completed 2407 C: A202 LIST ~/Mail/ % 2408 S: * LIST (\Noselect) "/" ~/Mail/foo 2409 S: * LIST () "/" ~/Mail/meetings 2410 S: A202 OK LIST completed 2412 Extended examples: 2414 1: The first example shows the complete local hierarchy that will 2415 be used for the other examples. 2417 C: A01 LIST "" "*" 2418 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2419 S: * LIST () "/" "Fruit" 2420 S: * LIST () "/" "Fruit/Apple" 2421 S: * LIST () "/" "Fruit/Banana" 2422 S: * LIST () "/" "Tofu" 2423 S: * LIST () "/" "Vegetable" 2424 S: * LIST () "/" "Vegetable/Broccoli" 2425 S: * LIST () "/" "Vegetable/Corn" 2426 S: A01 OK done 2428 2: In the next example, we will see the subscribed mailboxes. This 2429 is similar to, but not equivalent with, . Note 2430 that the mailbox called "Fruit/Peach" is subscribed to, but does 2431 not actually exist (perhaps it was deleted while still 2432 subscribed). The "Fruit" mailbox is not subscribed to, but it 2433 has two subscribed children. The "Vegetable" mailbox is 2434 subscribed and has two children; one of them is subscribed as 2435 well. 2437 C: A02 LIST (SUBSCRIBED) "" "*" 2438 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2439 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2440 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2441 S: * LIST (\Subscribed) "/" "Vegetable" 2442 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2443 S: A02 OK done 2445 3: The next example shows the use of the CHILDREN option. The 2446 client, without having to list the second level of hierarchy, 2447 now knows which of the top-level mailboxes have submailboxes 2448 (children) and which do not. Note that it's not necessary for 2449 the server to return the \HasNoChildren attribute for the inbox, 2450 because the \NoInferiors attribute already implies that, and has 2451 a stronger meaning. 2453 C: A03 LIST () "" "%" RETURN (CHILDREN) 2454 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2455 S: * LIST (\HasChildren) "/" "Fruit" 2456 S: * LIST (\HasNoChildren) "/" "Tofu" 2457 S: * LIST (\HasChildren) "/" "Vegetable" 2458 S: A03 OK done 2460 4: In this example, we see more mailboxes that reside on another 2461 server. This is similar to the command . 2463 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2464 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2465 S: * LIST (\HasChildren) "/" "Fruit" 2466 S: * LIST (\HasNoChildren) "/" "Tofu" 2467 S: * LIST (\HasChildren) "/" "Vegetable" 2468 S: * LIST (\Remote) "/" "Bread" 2469 S: * LIST (\HasChildren \Remote) "/" "Meat" 2470 S: A04 OK done 2472 5: The following example also requests the server to include 2473 mailboxes that reside on another server. The server returns 2474 information about all mailboxes that are subscribed. This is 2475 similar to the command . We also see the use of 2476 two selection options. 2478 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2479 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2480 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2481 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2482 S: * LIST (\Subscribed) "/" "Vegetable" 2483 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2484 S: * LIST (\Remote \Subscribed) "/" "Bread" 2485 S: A05 OK done 2487 6: The following example requests the server to include mailboxes 2488 that reside on another server. The server is asked to return 2489 subscription information for all returned mailboxes. This is 2490 different from the example above. 2492 Note that the output of this command is not a superset of the 2493 output in the previous example, as it doesn't include LIST 2494 response for the non-existent "Fruit/Peach". 2496 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2497 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2498 S: * LIST () "/" "Fruit" 2499 S: * LIST () "/" "Fruit/Apple" 2500 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2501 S: * LIST () "/" "Tofu" 2502 S: * LIST (\Subscribed) "/" "Vegetable" 2503 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2504 S: * LIST () "/" "Vegetable/Corn" 2505 S: * LIST (\Remote \Subscribed) "/" "Bread" 2506 S: * LIST (\Remote) "/" "Meat" 2507 S: A06 OK done 2509 7: In the following example, the client has specified multiple 2510 mailbox patterns. Note that this example does not use the 2511 mailbox hierarchy used in the previous examples. 2513 C: BBB LIST "" ("INBOX" "Drafts" "Sent/%") 2514 S: * LIST () "/" "INBOX" 2515 S: * LIST (\NoInferiors) "/" "Drafts" 2516 S: * LIST () "/" "Sent/March2004" 2517 S: * LIST (\Marked) "/" "Sent/December2003" 2518 S: * LIST () "/" "Sent/August2004" 2519 S: BBB OK done 2521 8: The following example demonstrates the difference between the 2522 \HasChildren attribute and the CHILDINFO extended data item. 2524 Let's assume there is the following hierarchy: 2526 C: C01 LIST "" "*" 2527 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2528 S: * LIST () "/" "Foo" 2529 S: * LIST () "/" "Foo/Bar" 2530 S: * LIST () "/" "Foo/Baz" 2531 S: * LIST () "/" "Moo" 2532 S: C01 OK done 2534 If the client asks RETURN (CHILDREN), it will get this: 2536 C: CA3 LIST "" "%" RETURN (CHILDREN) 2537 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2538 S: * LIST (\HasChildren) "/" "Foo" 2539 S: * LIST (\HasNoChildren) "/" "Moo" 2540 S: CA3 OK done 2542 A) Let's also assume that the mailbox "Foo/Baz" is the only 2543 subscribed mailbox. Then we get this result: 2545 C: C02 LIST (SUBSCRIBED) "" "*" 2546 S: * LIST (\Subscribed) "/" "Foo/Baz" 2547 S: C02 OK done 2549 Now, if the client issues , the server 2550 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2551 "Inbox" are NOT subscribed). However, if the client issues 2552 this: 2554 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2555 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2556 S: C04 OK done 2558 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2559 that is.) 2561 A1) If the mailbox "Foo" had also been subscribed, the last 2562 command would return this: 2564 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2565 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2566 S: C04 OK done 2568 or even this: 2570 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2571 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2572 ("SUBSCRIBED")) 2573 S: C04 OK done 2575 A2) If we assume instead that the mailbox "Foo" is not part of 2576 the original hierarchy and is not subscribed, the last command 2577 will give this result: 2579 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2580 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2581 S: C04 OK done 2582 B) Now, let's assume that no mailbox is subscribed. In this 2583 case, the command will 2584 return no responses, as there are no subscribed children (even 2585 though "Foo" has children). 2587 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2588 are subscribed. In that case, we see this result: 2590 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2591 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2592 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2593 S: C04 OK done 2595 (which means that the mailbox "Foo" has children, but none of 2596 them is subscribed). 2598 9: The following example demonstrates that the CHILDINFO extended 2599 data item is returned whether or not children mailboxes match 2600 the canonical LIST pattern. 2602 Let's assume there is the following hierarchy: 2604 C: D01 LIST "" "*" 2605 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2606 S: * LIST () "/" "foo2" 2607 S: * LIST () "/" "foo2/bar1" 2608 S: * LIST () "/" "foo2/bar2" 2609 S: * LIST () "/" "baz2" 2610 S: * LIST () "/" "baz2/bar2" 2611 S: * LIST () "/" "baz2/bar22" 2612 S: * LIST () "/" "baz2/bar222" 2613 S: * LIST () "/" "eps2" 2614 S: * LIST () "/" "eps2/mamba" 2615 S: * LIST () "/" "qux2/bar2" 2616 S: D01 OK done 2618 And that the following mailboxes are subscribed: 2620 C: D02 LIST (SUBSCRIBED) "" "*" 2621 S: * LIST (\Subscribed) "/" "foo2/bar1" 2622 S: * LIST (\Subscribed) "/" "foo2/bar2" 2623 S: * LIST (\Subscribed) "/" "baz2/bar2" 2624 S: * LIST (\Subscribed) "/" "baz2/bar22" 2625 S: * LIST (\Subscribed) "/" "baz2/bar222" 2626 S: * LIST (\Subscribed) "/" "eps2" 2627 S: * LIST (\Subscribed) "/" "eps2/mamba" 2628 S: * LIST (\Subscribed) "/" "qux2/bar2" 2629 S: D02 OK done 2630 The client issues the following command first: 2632 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2633 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2634 S: * LIST (\Subscribed) "/" "foo2/bar2" 2635 S: * LIST (\Subscribed) "/" "baz2/bar2" 2636 S: * LIST (\Subscribed) "/" "baz2/bar22" 2637 S: * LIST (\Subscribed) "/" "baz2/bar222" 2638 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2639 S: * LIST (\Subscribed) "/" "qux2/bar2" 2640 S: D03 OK done 2642 and the server may also include (but this would violate a SHOULD 2643 NOT in Section 3.5, because CHILDINFO is redundant) 2645 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2646 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2648 The CHILDINFO extended data item is returned for mailboxes 2649 "foo2", "baz2", and "eps2", because all of them have subscribed 2650 children, even though for the mailbox "foo2" only one of the two 2651 subscribed children matches the pattern, for the mailbox "baz2" 2652 all the subscribed children match the pattern, and for the 2653 mailbox "eps2" none of the subscribed children matches the 2654 pattern. 2656 Note that if the client issues 2658 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2659 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2660 S: * LIST (\Subscribed) "/" "foo2/bar1" 2661 S: * LIST (\Subscribed) "/" "foo2/bar2" 2662 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2663 S: * LIST (\Subscribed) "/" "baz2/bar2" 2664 S: * LIST (\Subscribed) "/" "baz2/bar22" 2665 S: * LIST (\Subscribed) "/" "baz2/bar222" 2666 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2667 S: * LIST (\Subscribed) "/" "eps2/mamba" 2668 S: * LIST (\Subscribed) "/" "qux2/bar2" 2669 S: D03 OK done 2671 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2672 still have the CHILDINFO extended data item, even though this 2673 information is redundant and the client can determine it by 2674 itself. 2676 10: 2678 10: The following example shows usage of extended syntax for mailbox 2679 pattern. It also demonstrates that the presence of the 2680 CHILDINFO extended data item doesn't necessarily imply 2681 \HasChildren. 2683 C: a1 LIST "" ("foo") 2684 S: * LIST () "/" foo 2685 S: a1 OK done 2687 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2688 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2689 S: a2 OK done 2691 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2692 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2693 S: a3 OK done 2695 11: The following example shows how a server that supports missing 2696 mailbox hierarchy elements can signal to a client that didn't 2697 specify the RECURSIVEMATCH selection option that there is a 2698 child mailbox that matches the selection criteria. 2700 C: a1 LIST (REMOTE) "" * 2701 S: * LIST () "/" music/rock 2702 S: * LIST (\Remote) "/" also/jazz 2703 S: a1 OK done 2705 C: a2 LIST () "" % 2706 S: * LIST (\NonExistent \HasChildren) "/" music 2707 S: a2 OK done 2709 C: a3 LIST (REMOTE) "" % 2710 S: * LIST (\NonExistent \HasChildren) "/" music 2711 S: * LIST (\NonExistent \HasChildren) "/" also 2712 S: a3 OK done 2714 C: a3.1 LIST "" (% music/rock) 2715 S: * LIST () "/" music/rock 2716 S: a3.1 OK done 2718 Because "music/rock" is the only mailbox under "music", there's 2719 no need for the server to also return "music". However clients 2720 must handle both cases. 2722 12: The following examples show use of STATUS return option. 2724 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2725 S: * LIST () "." "INBOX" 2726 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2727 S: * LIST () "." "foo" 2728 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2729 S: * LIST (\NoSelect) "." "bar" 2730 S: A01 OK List completed. 2732 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2734 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2735 (MESSAGES)) 2736 S: * LIST (\Subscribed) "." "INBOX" 2737 S: * STATUS "INBOX" (MESSAGES 17) 2738 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2739 S: A02 OK List completed. 2741 The LIST reply for "foo" is returned because it has matching 2742 children, but no STATUS reply is returned because "foo" itself 2743 doesn't match the selection criteria. 2745 6.3.10. NAMESPACE Command 2747 Arguments: none 2749 Responses: REQUIRED untagged responses: NAMESPACE 2751 Result: OK - command completed 2752 NO - Can't complete the command 2753 BAD - arguments invalid 2755 The NAMESPACE command causes a single ungagged NAMESPACE response to 2756 be returned. The untagged NAMESPACE response contains the prefix and 2757 hierarchy delimiter to the server's Personal Namespace(s), Other 2758 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2759 to expose. The response will contain a NIL for any namespace class 2760 that is not available. Namespace-Response-Extensions ABNF non 2761 terminal is defined for extensibility and MAY be included in the 2762 response. 2764 Example 1: 2766 In this example a server supports a single personal namespace. No 2767 leading prefix is used on personal mailboxes and "/" is the hierarchy 2768 delimiter. 2770 C: A001 NAMESPACE 2771 S: * NAMESPACE (("" "/")) NIL NIL 2772 S: A001 OK NAMESPACE command completed 2774 Example 2: 2776 A user logged on anonymously to a server. No personal mailboxes are 2777 associated with the anonymous user and the user does not have access 2778 to the Other Users' Namespace. No prefix is required to access 2779 shared mailboxes and the hierarchy delimiter is "." 2781 C: A001 NAMESPACE 2782 S: * NAMESPACE NIL NIL (("" ".")) 2783 S: A001 OK NAMESPACE command completed 2785 Example 3: 2787 A server that contains a Personal Namespace and a single Shared 2788 Namespace. 2790 C: A001 NAMESPACE 2791 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2792 S: A001 OK NAMESPACE command completed 2794 Example 4: 2796 A server that contains a Personal Namespace, Other Users' Namespace 2797 and multiple Shared Namespaces. Note that the hierarchy delimiter 2798 used within each namespace can be different. 2800 C: A001 NAMESPACE 2801 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2802 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2803 S: A001 OK NAMESPACE command completed 2805 The prefix string allows a client to do things such as automatically 2806 creating personal mailboxes or LISTing all available mailboxes within 2807 a namespace. 2809 Example 5: 2811 A server that supports only the Personal Namespace, with a leading 2812 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2813 "." 2814 C: A001 NAMESPACE 2815 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2816 S: A001 OK NAMESPACE command completed 2818 < Automatically create a mailbox to store sent items.> 2820 C: A002 CREATE "INBOX.Sent Mail" 2821 S: A002 OK CREATE command completed 2823 Although typically a server will support only a single Personal 2824 Namespace, and a single Other User's Namespace, circumstances exist 2825 where there MAY be multiples of these, and a client MUST be prepared 2826 for them. If a client is configured such that it is required to 2827 create a certain mailbox, there can be circumstances where it is 2828 unclear which Personal Namespaces it should create the mailbox in. 2829 In these situations a client SHOULD let the user select which 2830 namespaces to create the mailbox in or just use the first personal 2831 namespace. 2833 Example 6: 2835 In this example, a server supports 2 Personal Namespaces. In 2836 addition to the regular Personal Namespace, the user has an 2837 additional personal namespace to allow access to mailboxes in an MH 2838 format mailstore. 2840 The client is configured to save a copy of all mail sent by the user 2841 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2842 deleted from a mailbox, the client is configured to move that message 2843 to a mailbox called 'Deleted Items'. 2845 Note that this example demonstrates how some extension flags can be 2846 passed to further describe the #mh namespace. 2848 C: A001 NAMESPACE 2849 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2850 ("FLAG1" "FLAG2"))) NIL NIL 2851 S: A001 OK NAMESPACE command completed 2853 < It is desired to keep only one copy of sent mail. 2854 It is unclear which Personal Namespace the client 2855 should use to create the 'Sent Mail' mailbox. 2856 The user is prompted to select a namespace and only 2857 one 'Sent Mail' mailbox is created. > 2859 C: A002 CREATE "Sent Mail" 2860 S: A002 OK CREATE command completed 2862 < The client is designed so that it keeps two 2863 'Deleted Items' mailboxes, one for each namespace. > 2865 C: A003 CREATE "Delete Items" 2866 S: A003 OK CREATE command completed 2868 C: A004 CREATE "#mh/Deleted Items" 2869 S: A004 OK CREATE command completed 2871 The next level of hierarchy following the Other Users' Namespace 2872 prefix SHOULD consist of , where is a user name 2873 as per the LOGIN or AUTHENTICATE command. 2875 A client can construct a LIST command by appending a "%" to the Other 2876 Users' Namespace prefix to discover the Personal Namespaces of other 2877 users that are available to the currently authenticated user. 2879 In response to such a LIST command, a server SHOULD NOT return user 2880 names that have not granted access to their personal mailboxes to the 2881 user in question. 2883 A server MAY return a LIST response containing only the names of 2884 users that have explicitly granted access to the user in question. 2886 Alternatively, a server MAY return NO to such a LIST command, 2887 requiring that a user name be included with the Other Users' 2888 Namespace prefix before listing any other user's mailboxes. 2890 Example 7: 2892 A server that supports providing a list of other user's mailboxes 2893 that are accessible to the currently logged on user. 2895 C: A001 NAMESPACE 2896 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 2897 S: A001 OK NAMESPACE command completed 2899 C: A002 LIST "" "Other Users/%" 2900 S: * LIST () "/" "Other Users/Mike" 2901 S: * LIST () "/" "Other Users/Karen" 2902 S: * LIST () "/" "Other Users/Matthew" 2903 S: * LIST () "/" "Other Users/Tesa" 2904 S: A002 OK LIST command completed 2906 Example 8: 2908 A server that does not support providing a list of other user's 2909 mailboxes that are accessible to the currently logged on user. The 2910 mailboxes are listable if the client includes the name of the other 2911 user with the Other Users' Namespace prefix. 2913 C: A001 NAMESPACE 2914 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 2915 S: A001 OK NAMESPACE command completed 2917 < In this example, the currently logged on user has access to 2918 the Personal Namespace of user Mike, but the server chose to 2919 suppress this information in the LIST response. However, 2920 by appending the user name Mike (received through user input) 2921 to the Other Users' Namespace prefix, the client is able 2922 to get a listing of the personal mailboxes of user Mike. > 2924 C: A002 LIST "" "#Users/%" 2925 S: A002 NO The requested item could not be found. 2927 C: A003 LIST "" "#Users/Mike/%" 2928 S: * LIST () "/" "#Users/Mike/INBOX" 2929 S: * LIST () "/" "#Users/Mike/Foo" 2930 S: A003 OK LIST command completed. 2932 A prefix string might not contain a hierarchy delimiter, because in 2933 some cases it is not needed as part of the prefix. 2935 Example 9: 2937 A server that allows access to the Other Users' Namespace by 2938 prefixing the others' mailboxes with a '~' followed by , 2939 where is a user name as per the LOGIN or AUTHENTICATE 2940 command. 2942 C: A001 NAMESPACE 2943 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 2944 S: A001 OK NAMESPACE command completed 2946 < List the mailboxes for user mark > 2948 C: A002 LIST "" "~mark/%" 2949 S: * LIST () "/" "~mark/INBOX" 2950 S: * LIST () "/" "~mark/foo" 2951 S: A002 OK LIST command completed 2953 6.3.11. STATUS Command 2955 Arguments: mailbox name 2956 status data item names 2958 Responses: REQUIRED untagged responses: STATUS 2960 Result: OK - status completed 2961 NO - status failure: no status for that name 2962 BAD - command unknown or arguments invalid 2964 The STATUS command requests the status of the indicated mailbox. It 2965 does not change the currently selected mailbox, nor does it affect 2966 the state of any messages in the queried mailbox. 2968 The STATUS command provides an alternative to opening a second 2969 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 2970 query that mailbox's status without deselecting the current mailbox 2971 in the first IMAP4rev2 connection. 2973 Unlike the LIST command, the STATUS command is not guaranteed to be 2974 fast in its response. Under certain circumstances, it can be quite 2975 slow. In some implementations, the server is obliged to open the 2976 mailbox read-only internally to obtain certain status information. 2977 Also unlike the LIST command, the STATUS command does not accept 2978 wildcards. 2980 Note: The STATUS command is intended to access the status of 2981 mailboxes other than the currently selected mailbox. Because the 2982 STATUS command can cause the mailbox to be opened internally, and 2983 because this information is available by other means on the 2984 selected mailbox, the STATUS command SHOULD NOT be used on the 2985 currently selected mailbox. 2987 The STATUS command MUST NOT be used as a "check for new messages 2988 in the selected mailbox" operation (refer to sections Section 7, 2989 Section 7.3.1 for more information about the proper method for new 2990 message checking). 2992 STATUS SIZE (see below) can take a significant amount of time, 2993 depending upon server implementation. Clients should use STATUS 2994 SIZE cautiously. 2996 The currently defined status data items that can be requested are: 2998 MESSAGES The number of messages in the mailbox. 3000 UIDNEXT The next unique identifier value of the mailbox. Refer to 3001 Section 2.3.1.1 for more information. 3003 UIDVALIDITY The unique identifier validity value of the mailbox. 3004 Refer to Section 2.3.1.1 for more information. 3006 UNSEEN The number of messages which do not have the \Seen flag set. 3008 DELETED The number of messages which have the \Deleted flag set. 3010 SIZE The total size of the mailbox in octets. This is not strictly 3011 required to be an exact value, but it MUST be equal to or greater 3012 than the sum of the values of the RFC822.SIZE FETCH message data 3013 items (see Section 6.4.5) of all messages in the mailbox. 3015 SIZE 3017 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3018 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3019 S: A042 OK STATUS completed 3021 6.3.12. APPEND Command 3023 Arguments: mailbox name 3024 OPTIONAL flag parenthesized list 3025 OPTIONAL date/time string 3026 message literal 3028 Responses: no specific responses for this command 3030 Result: OK - append completed 3031 NO - append error: can't append to that mailbox, error 3032 in flags or date/time or message text 3033 BAD - command unknown or arguments invalid 3035 The APPEND command appends the literal argument as a new message to 3036 the end of the specified destination mailbox. This argument SHOULD 3037 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3038 characters are permitted in the message. A server implementation 3039 that is unable to preserve 8-bit data properly MUST be able to 3040 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3041 content transfer encoding. 3043 Note: There may be exceptions, e.g., draft messages, in which 3044 required [RFC-5322] header lines are omitted in the message 3045 literal argument to APPEND. The full implications of doing so 3046 must be understood and carefully weighed. 3048 If a flag parenthesized list is specified, the flags SHOULD be set in 3049 the resulting message; otherwise, the flag list of the resulting 3050 message is set to empty by default. 3052 If a date-time is specified, the internal date SHOULD be set in the 3053 resulting message; otherwise, the internal date of the resulting 3054 message is set to the current date and time by default. 3056 If the append is unsuccessful for any reason, the mailbox MUST be 3057 restored to its state before the APPEND attempt (other than possibly 3058 keeping the changed mailbox's UIDNEXT value); no partial appending is 3059 permitted. 3061 If the destination mailbox does not exist, a server MUST return an 3062 error, and MUST NOT automatically create the mailbox. Unless it is 3063 certain that the destination mailbox can not be created, the server 3064 MUST send the response code "[TRYCREATE]" as the prefix of the text 3065 of the tagged NO response. This gives a hint to the client that it 3066 can attempt a CREATE command and retry the APPEND if the CREATE is 3067 successful. 3069 On successful completion of an APPEND, the server SHOULD return an 3070 APPENDUID response code. 3072 In the case of a mailbox that has permissions set so that the client 3073 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3074 SHOULD NOT send an APPENDUID response code as it would disclose 3075 information about the mailbox. 3077 In the case of a mailbox that has UIDNOTSTICKY status (see 3078 UIDNOTSTICKY response code definition), the server MAY omit the 3079 APPENDUID response code as it is not meaningful. 3081 If the server does not return the APPENDUID response codes, the 3082 client can discover this information by selecting the destination 3083 mailbox. The location of messages placed in the destination mailbox 3084 by APPEND can be determined by using FETCH and/or SEARCH commands 3085 (e.g., for Message-ID or some unique marker placed in the message in 3086 an APPEND). 3088 If the mailbox is currently selected, the normal new message actions 3089 SHOULD occur. Specifically, the server SHOULD notify the client 3090 immediately via an untagged EXISTS response. If the server does not 3091 do so, the client MAY issue a NOOP command after one or more APPEND 3092 commands. 3094 Example: C: A003 APPEND saved-messages (\Seen) {310} 3095 S: + Ready for literal data 3096 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3097 C: From: Fred Foobar 3098 C: Subject: afternoon meeting 3099 C: To: mooch@owatagu.siam.edu 3100 C: Message-Id: 3101 C: MIME-Version: 1.0 3102 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3103 C: 3104 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3105 C: 3106 S: A003 OK APPEND completed 3108 Example: C: A003 APPEND saved-messages (\Seen) {297} 3109 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3110 C: From: Fred Foobar 3111 C: Subject: afternoon meeting 3112 C: To: mooch@example.com 3113 C: Message-Id: 3114 C: MIME-Version: 1.0 3115 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3116 C: 3117 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3118 C: 3119 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3120 C: A004 COPY 2:4 meeting 3121 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3122 C: A005 UID COPY 305:310 meeting 3123 S: A005 OK No matching messages, so nothing copied 3124 C: A006 COPY 2 funny 3125 S: A006 OK Done 3126 C: A007 SELECT funny 3127 S: * 1 EXISTS 3128 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3129 S: * OK [UIDNEXT 2] Predicted next UID 3130 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3131 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3132 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3133 S: A007 OK [READ-WRITE] SELECT completed 3135 In this example, A003 and A004 demonstrate successful appending and 3136 copying to a mailbox that returns the UIDs assigned to the messages. 3137 A005 is an example in which no messages were copied; this is because 3138 in A003, we see that message 2 had UID 304, and message 3 had UID 3139 319; therefore, UIDs 305 through 310 do not exist (refer to 3140 Section 2.3.1.1 for further explanation). A006 is an example of a 3141 message being copied that did not return a COPYUID; and, as expected, 3142 A007 shows that the mail store containing that mailbox does not 3143 support persistent UIDs. 3145 Note: The APPEND command is not used for message delivery, because 3146 it does not provide a mechanism to transfer [SMTP] envelope 3147 information. 3149 6.3.13. IDLE Command 3151 Arguments: none 3153 Responses: continuation data will be requested; the client sends the 3154 continuation data "DONE" to end the command 3156 Result: OK - IDLE completed after client sent "DONE" 3157 NO - failure: the server will not allow the IDLE command 3158 at this time 3159 BAD - command unknown or arguments invalid 3161 Without the IDLE command a client requires to poll the server for 3162 changes to the selected mailbox (new mail, deletions, flag changes). 3163 It's often more desirable to have the server transmit updates to the 3164 client in real time. This allows a user to see new mail immediately. 3165 The IDLE command allows a client to tell the server that it's ready 3166 to accept such real-time updates. 3168 The IDLE command is sent from the client to the server when the 3169 client is ready to accept unsolicited update messages. The server 3170 requests a response to the IDLE command using the continuation ("+") 3171 response. The IDLE command remains active until the client responds 3172 to the continuation, and as long as an IDLE command is active, the 3173 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3174 responses at any time. If the server choose to send unsolicited 3175 FETCH responses, they MUST include UID FETCH item. 3177 The IDLE command is terminated by the receipt of a "DONE" 3178 continuation from the client; such response satisfies the server's 3179 continuation request. At that point, the server MAY send any 3180 remaining queued untagged responses and then MUST immediately send 3181 the tagged response to the IDLE command and prepare to process other 3182 commands. As for other commands, the processing of any new command 3183 may cause the sending of unsolicited untagged responses, subject to 3184 the ambiguity limitations. The client MUST NOT send a command while 3185 the server is waiting for the DONE, since the server will not be able 3186 to distinguish a command from a continuation. 3188 The server MAY consider a client inactive if it has an IDLE command 3189 running, and if such a server has an inactivity timeout it MAY log 3190 the client off implicitly at the end of its timeout period. Because 3191 of that, clients using IDLE are advised to terminate the IDLE and re- 3192 issue it at least every 29 minutes to avoid being logged off. This 3193 still allows a client to receive immediate mailbox updates even 3194 though it need only "poll" at half hour intervals. 3196 Example: C: A001 SELECT INBOX 3197 S: * FLAGS (\Deleted \Seen \Flagged) 3198 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3199 S: * 3 EXISTS 3200 S: * OK [UIDVALIDITY 1] 3201 S: A001 OK [READ-WRITE] SELECT completed 3202 C: A002 IDLE 3203 S: + idling 3204 ...time passes; new mail arrives... 3205 S: * 4 EXISTS 3206 C: DONE 3207 S: A002 OK IDLE terminated 3208 ...another client expunges message 2 now... 3209 C: A003 FETCH 4 ALL 3210 S: * 4 FETCH (...) 3211 S: A003 OK FETCH completed 3212 C: A004 IDLE 3213 S: * 2 EXPUNGE 3214 S: * 3 EXISTS 3215 S: + idling 3216 ...time passes; another client expunges message 3... 3217 S: * 3 EXPUNGE 3218 S: * 2 EXISTS 3219 ...time passes; new mail arrives... 3220 S: * 3 EXISTS 3221 C: DONE 3222 S: A004 OK IDLE terminated 3223 C: A005 FETCH 3 ALL 3224 S: * 3 FETCH (...) 3225 S: A005 OK FETCH completed 3226 C: A006 IDLE 3228 6.4. Client Commands - Selected State 3230 In the selected state, commands that manipulate messages in a mailbox 3231 are permitted. 3233 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3234 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3235 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3236 APPEND), the following commands are valid in the selected state: 3237 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3239 6.4.1. CLOSE Command 3241 Arguments: none 3243 Responses: no specific responses for this command 3244 Result: OK - close completed, now in authenticated state 3245 BAD - command unknown or arguments invalid 3247 The CLOSE command permanently removes all messages that have the 3248 \Deleted flag set from the currently selected mailbox, and returns to 3249 the authenticated state from the selected state. No untagged EXPUNGE 3250 responses are sent. 3252 No messages are removed, and no error is given, if the mailbox is 3253 selected by an EXAMINE command or is otherwise selected read-only. 3255 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3256 MAY be issued without previously issuing a CLOSE command. The 3257 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3258 selected mailbox without doing an expunge. However, when many 3259 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3260 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3261 no untagged EXPUNGE responses (which the client would probably 3262 ignore) are sent. 3264 Example: C: A341 CLOSE 3265 S: A341 OK CLOSE completed 3267 6.4.2. UNSELECT Command 3269 Arguments: none 3271 Responses: no specific responses for this command 3273 Result: OK - unselect completed, now in authenticated state 3274 BAD - no mailbox selected, or argument supplied but none 3275 permitted 3277 The UNSELECT command frees server's resources associated with the 3278 selected mailbox and returns the server to the authenticated state. 3279 This command performs the same actions as CLOSE, except that no 3280 messages are permanently removed from the currently selected mailbox. 3282 Example: C: A342 UNSELECT 3283 S: A342 OK Unselect completed 3285 6.4.3. EXPUNGE Command 3287 Arguments: none 3289 Responses: untagged responses: EXPUNGE 3291 Result: OK - expunge completed 3292 NO - expunge failure: can't expunge (e.g., permission 3293 denied) 3294 BAD - command unknown or arguments invalid 3296 The EXPUNGE command permanently removes all messages that have the 3297 \Deleted flag set from the currently selected mailbox. Before 3298 returning an OK to the client, an untagged EXPUNGE response is sent 3299 for each message that is removed. 3301 Example: C: A202 EXPUNGE 3302 S: * 3 EXPUNGE 3303 S: * 3 EXPUNGE 3304 S: * 5 EXPUNGE 3305 S: * 8 EXPUNGE 3306 S: A202 OK EXPUNGE completed 3308 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3309 set. See the description of the EXPUNGE response for further 3310 explanation. 3312 6.4.4. SEARCH Command 3314 Arguments: OPTIONAL result specifier 3315 OPTIONAL [CHARSET] specification 3316 searching criteria (one or more) 3318 Responses: OPTIONAL untagged response: ESEARCH 3320 Result: OK - search completed 3321 NO - search error: can't search that [CHARSET] or 3322 criteria 3323 BAD - command unknown or arguments invalid 3325 The SEARCH command searches the mailbox for messages that match the 3326 given searching criteria. 3328 The SEARCH command may contain result options. Result options 3329 control what kind of information is returned about messages matching 3330 the search criteria in an untagged ESEARCH response. If no result 3331 option is specified or empty list of options is specified "()", ALL 3332 is assumed (see below). The order of individual options is 3333 arbitrary. Individual options may contain parameters enclosed in 3334 parentheses (*). If an option has parameters, they consist of atoms 3335 and/or strings and/or lists in a specific order. Any options not 3336 defined by extensions that the server supports must be rejected with 3337 a BAD response. 3339 (*) - if an option has a mandatory parameter, which can always be 3340 represented as a number or a sequence-set, the option parameter does 3341 not need the enclosing (). See ABNF for more details. 3343 This document specifies the following result options: 3345 MIN 3347 Return the lowest message number/UID that satisfies the SEARCH 3348 criteria. 3350 If the SEARCH results in no matches, the server MUST NOT 3351 include the MIN result option in the ESEARCH response; however, 3352 it still MUST send the ESEARCH response. 3354 MAX 3356 Return the highest message number/UID that satisfies the SEARCH 3357 criteria. 3359 If the SEARCH results in no matches, the server MUST NOT 3360 include the MAX result option in the ESEARCH response; however, 3361 it still MUST send the ESEARCH response. 3363 ALL 3365 Return all message numbers/UIDs that satisfy the SEARCH 3366 criteria using the sequence-set syntax. Note, the client MUST 3367 NOT assume that messages/UIDs will be listed in any particular 3368 order. 3370 If the SEARCH results in no matches, the server MUST NOT 3371 include the ALL result option in the ESEARCH response; however, 3372 it still MUST send the ESEARCH response. 3374 COUNT Return number of the messages that satisfy the SEARCH 3375 criteria. This result option MUST always be included in the 3376 ESEARCH response. 3378 SAVE 3380 This option tells the server to remember the result of the 3381 SEARCH or UID SEARCH command (as well as any command based on 3382 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3383 internal variable that we will reference as the "search result 3384 variable". The client can use the "$" marker to reference the 3385 content of this internal variable. The "$" marker can be used 3386 instead of message sequence or UID sequence in order to 3387 indicate that the server should substitute it with the list of 3388 messages from the search result variable. Thus, the client can 3389 use the result of the latest remembered SEARCH command as a 3390 parameter to another command. See Section 6.4.4.1 for details 3391 on how the value of the search result variable is determined, 3392 how it is affected by other commands executed, and how SAVE 3393 return option interacts with other return options. 3395 In absence of any other SEARCH result option, the SAVE result 3396 option also suppresses any ESEARCH response that would have 3397 been otherwise returned by the SEARCH command. 3399 Note: future extensions to this document can allow servers to return 3400 multiple ESEARCH responses for a single extended SEARCH command. 3401 However all options specified above MUST result in a single ESEARCH 3402 response. 3404 These extensions will have to describe how results from multiple 3405 ESEARCH responses are to be amalgamated. 3407 Searching criteria consist of one or more search keys. 3409 When multiple keys are specified, the result is the intersection (AND 3410 function) of all the messages that match those keys. For example, 3411 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3412 deleted messages from Smith that were placed in the mailbox since 3413 February 1, 1994. A search key can also be a parenthesized list of 3414 one or more search keys (e.g., for use with the OR and NOT keys). 3416 Server implementations MAY exclude [MIME-IMB] body parts with 3417 terminal content media types other than TEXT and MESSAGE from 3418 consideration in SEARCH matching. 3420 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3421 followed by a registered [CHARSET]. It indicates the [CHARSET] of 3422 the strings that appear in the search criteria. [MIME-IMB] content 3423 transfer encodings, and [MIME-HDRS] strings in [RFC-5322]/[MIME-IMB] 3424 headers, MUST be decoded before comparing text. Servers MUST support 3425 US-ASCII and UTF-8 charsets; other [CHARSET]s MAY be supported. 3426 Clients SHOULD use UTF-8. Note that if "CHARSET" is not provided 3427 IMAP4rev2 server MUST assume UTF-8, so selecting CHARSET UTF-8 is 3428 redundant. It is permitted for improved compatibility with existing 3429 IMAP4rev1 clients. 3431 If the server does not support the specified [CHARSET], it MUST 3432 return a tagged NO response (not a BAD). This response SHOULD 3433 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3434 supported by the server. 3436 In all search keys that use strings, a message matches the key if the 3437 string is a substring of the associated text. The matching SHOULD be 3438 case-insensitive for characters within ASCII range. Consider using 3439 [IMAP-I18N] for language-sensitive case-insensitive searching. Note 3440 that the empty string is a substring; this is useful when doing a 3441 HEADER search in order to test for a header field presence in the 3442 message. 3444 The defined search keys are as follows. Refer to the Formal Syntax 3445 section for the precise syntactic definitions of the arguments. 3447 3449 Messages with message sequence numbers corresponding 3450 to the specified message sequence number set. 3452 ALL All messages in the mailbox; the default initial key for ANDing. 3454 ANSWERED Messages with the \Answered flag set. 3456 BCC Messages that contain the specified string in the 3457 envelope structure's BCC field. 3459 BEFORE Messages whose internal date (disregarding time and 3460 timezone) is earlier than the specified date. 3462 BODY Messages that contain the specified string in the body 3463 of the message. Unlike TEXT (see below), this doesn't match any 3464 header fields. 3466 CC Messages that contain the specified string in the 3467 envelope structure's CC field. 3469 DELETED Messages with the \Deleted flag set. 3471 DRAFT Messages with the \Draft flag set. 3473 FLAGGED Messages with the \Flagged flag set. 3475 FROM Messages that contain the specified string in the 3476 envelope structure's FROM field. 3478 HEADER Messages that have a header with the 3479 specified field-name (as defined in [RFC-5322]) and that contains 3480 the specified string in the text of the header (what comes after 3481 the colon). If the string to search is zero-length, this matches 3482 all messages that have a header line with the specified field-name 3483 regardless of the contents. Servers should use substring search 3484 for this SEARCH item, as clients can use it for automatic 3485 processing not initiated by end users. For example this can be 3486 used for searching for Message-ID or Content-Type header field 3487 values that need to be exact, or for searches in header fields 3488 that the IMAP server might not know anything about. 3490 KEYWORD Messages with the specified keyword flag set. 3492 LARGER Messages with an [RFC-5322] size larger than the 3493 specified number of octets. 3495 NOT Messages that do not match the specified search 3496 key. 3498 ON Messages whose internal date (disregarding time and 3499 timezone) is within the specified date. 3501 OR Messages that match either search 3502 key. 3504 SEEN Messages that have the \Seen flag set. 3506 SENTBEFORE Messages whose [RFC-5322] Date: header 3507 (disregarding time and timezone) is earlier than the specified 3508 date. 3510 SENTON Messages whose [RFC-5322] Date: header (disregarding 3511 time and timezone) is within the specified date. 3513 SENTSINCE Messages whose [RFC-5322] Date: header 3514 (disregarding time and timezone) is within or later than the 3515 specified date. 3517 SINCE Messages whose internal date (disregarding time and 3518 timezone) is within or later than the specified date. 3520 SMALLER Messages with an [RFC-5322] size smaller than the 3521 specified number of octets. 3523 SUBJECT Messages that contain the specified string in the 3524 envelope structure's SUBJECT field. 3526 TEXT Messages that contain the specified string in the 3527 header (including MIME header fields) or body of the message. 3529 TO Messages that contain the specified string in the 3530 envelope structure's TO field. 3532 UID Messages with unique identifiers corresponding to 3533 the specified unique identifier set. Sequence set ranges are 3534 permitted. 3536 UNANSWERED Messages that do not have the \Answered flag set. 3538 UNDELETED Messages that do not have the \Deleted flag set. 3540 UNDRAFT Messages that do not have the \Draft flag set. 3542 UNFLAGGED Messages that do not have the \Flagged flag set. 3544 UNKEYWORD Messages that do not have the specified keyword 3545 flag set. 3547 UNSEEN Messages that do not have the \Seen flag set. 3549 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3550 SINCE 1-Feb-1994 NOT FROM "Smith" 3551 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3552 S: A282 OK SEARCH completed 3554 Example: C: A283 SEARCH RETURN () FLAGGED 3555 SINCE 1-Feb-1994 NOT FROM "Smith" 3556 S: * ESEARCH (TAG "A283") ALL 2,10:11 3557 S: A283 OK SEARCH completed 3559 Example: C: A284 SEARCH TEXT "string not in mailbox" 3560 S: * ESEARCH (TAG "A284") 3561 S: A284 OK SEARCH completed 3562 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3563 S: + Ready for literal text 3564 C: XXXXXX 3565 S: * ESEARCH (TAG "A285") ALL 43 3566 S: A285 OK SEARCH completed 3568 Note: Since this document is restricted to 7-bit ASCII text, it is 3569 not possible to show actual UTF-8 data. The "XXXXXX" is a 3570 placeholder for what would be 6 octets of 8-bit data in an actual 3571 transaction. 3573 The following example demonstrates finding the first unseen message 3574 in the mailbox: 3576 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3577 S: * ESEARCH (TAG "A284") MIN 4 3578 S: A284 OK SEARCH completed 3580 The following example demonstrates that if the ESEARCH UID indicator 3581 is present, all data in the ESEARCH response is referring to UIDs; 3582 for example, the MIN result specifier will be followed by a UID. 3584 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3585 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3586 S: A285 OK SEARCH completed 3588 The following example demonstrates returning the number of deleted 3589 messages: 3591 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3592 S: * ESEARCH (TAG "A286") COUNT 15 3593 S: A286 OK SEARCH completed 3595 6.4.4.1. SAVE result option and SEARCH result variable 3597 Upon successful completion of a SELECT or an EXAMINE command (after 3598 the tagged OK response), the current search result variable is reset 3599 to the empty sequence. 3601 A successful SEARCH command with the SAVE result option sets the 3602 value of the search result variable to the list of messages found in 3603 the SEARCH command. For example, if no messages were found, the 3604 search result variable will contain the empty sequence. 3606 Any of the following SEARCH commands MUST NOT change the search 3607 result variable: 3609 a SEARCH command that caused the server to return the BAD tagged 3610 response, 3612 a SEARCH command with no SAVE result option that caused the server 3613 to return NO tagged response, 3615 a successful SEARCH command with no SAVE result option. 3617 A SEARCH command with the SAVE result option that caused the server 3618 to return the NO tagged response sets the value of the search result 3619 variable to the empty sequence. 3621 When a message listed in the search result variable is EXPUNGEd, it 3622 is automatically removed from the list. Implementors are reminded 3623 that if the server stores the list as a list of message numbers, it 3624 MUST automatically adjust them when notifying the client about 3625 expunged messages, as described in Section 7.4.1. 3627 If the server decides to send a new UIDVALIDITY value while the 3628 mailbox is opened, this causes resetting of the search variable to 3629 the empty sequence. 3631 Note that even if the "$" marker contains the empty sequence of 3632 messages, it must be treated by all commands accepting message sets 3633 as parameters as a valid, but non-matching list of messages. For 3634 example, the "FETCH $" command would return a tagged OK response and 3635 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3637 The SAVE result option doesn't change whether the server would return 3638 items corresponding to MIN, MAX, ALL, or COUNT result options. 3640 When the SAVE result option is combined with the MIN or MAX result 3641 option, and both ALL and COUNT result options are absent, the 3642 corresponding MIN/MAX is returned (if the search result is not 3643 empty), but the "$" marker would contain a single message as returned 3644 in the MIN/MAX return item. 3646 If the SAVE result option is combined with both MIN and MAX result 3647 options, and both ALL and COUNT result options are absent, the "$" 3648 marker would contain zero, one or two messages as returned in the 3649 MIN/MAX return items. 3651 If the SAVE result option is combined with the ALL and/or COUNT 3652 result option(s), the "$" marker would always contain all messages 3653 found by the SEARCH or UID SEARCH command. 3655 The following table summarizes the additional requirement on ESEARCH 3656 server implementations described in this section. 3658 +------------------------------+--------------------+ 3659 | Combination of Result option | "$" marker value | 3660 +------------------------------+--------------------+ 3661 | SAVE MIN | MIN | 3662 | SAVE MAX | MAX | 3663 | SAVE MIN MAX | MIN & MAX | 3664 | SAVE * [m] | all found messages | 3665 +------------------------------+--------------------+ 3667 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3668 and/or "MAX" 3670 Implementation note: server implementors should note that "$" can 3671 reference IMAP message sequences or UID sequences, depending on the 3672 context where it is used. For example, the "$" marker can be set as 3673 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3674 FETCH command (which accepts a UID sequence, not a message sequence), 3675 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3676 command and used as a parameter to a FETCH command (which accepts a 3677 message sequence, not a UID sequence). Server implementations need 3678 to automatically map the "$" marker value to message numbers or UIDs, 3679 depending on context where the "$" marker is used. 3681 6.4.4.2. Multiple Commands in Progress 3683 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3684 "$" marker creates direct dependency between the two commands. As 3685 directed by Section 5.5, a server MUST execute the two commands in 3686 the order they were received. 3688 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3689 command using the "$" marker, as long as this doesn't create an 3690 ambiguity, as described in by Section 5.5. Examples 7-9 in 3691 Section 6.4.4.4 explain this in more details. 3693 6.4.4.3. Refusing to Save Search Results 3695 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3696 for example, if an internal limit on the number of saved results is 3697 reached. In this case, the server MUST return a tagged NO response 3698 containing the NOTSAVED response code and set the search result 3699 variable to the empty sequence, as described in Section 6.4.4.1. 3701 6.4.4.4. Examples showing use of SAVE result option 3703 Only in this section: explanatory comments in examples that start 3704 with // are not part of the protocol. 3706 1) The following example demonstrates how the client can use the 3707 result of a SEARCH command to FETCH headers of interesting messages: 3709 Example 1: 3710 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3711 NOT FROM "Smith" 3712 S: A282 OK SEARCH completed, result saved 3713 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3714 S: * 2 FETCH (UID 14 ... 3715 S: * 84 FETCH (UID 100 ... 3716 S: * 882 FETCH (UID 1115 ... 3717 S: A283 OK completed 3719 The client can also pipeline the two commands: 3721 Example 2: 3722 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3723 NOT FROM "Smith" 3724 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3725 S: A282 OK SEARCH completed 3726 S: * 2 FETCH (UID 14 ... 3727 S: * 84 FETCH (UID 100 ... 3728 S: * 882 FETCH (UID 1115 ... 3729 S: A283 OK completed 3731 2) The following example demonstrates that the result of one SEARCH 3732 command can be used as input to another SEARCH command: 3734 Example 3: 3735 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3736 NOT FROM "Smith" 3737 S: A300 OK SEARCH completed 3738 C: A301 UID SEARCH UID $ SMALLER 4096 3739 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3740 S: A301 OK completed 3742 Note that the second command in Example 3 can be replaced with: 3743 C: A301 UID SEARCH $ SMALLER 4096 3744 and the result of the command would be the same. 3746 3) The following example shows that the "$" marker can be combined 3747 with other message numbers using the OR SEARCH criterion. 3749 Example 4: 3750 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3751 NOT FROM "Smith" 3752 S: P282 OK SEARCH completed 3753 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3754 C: YYYYYYYY 3755 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3756 S: P283 OK completed 3758 Note: Since this document format is restricted to 7-bit ASCII text, 3759 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3760 placeholder for what would be 8 octets of 8-bit data in an actual 3761 transaction. 3763 4) The following example demonstrates that a failed SEARCH sets the 3764 search result variable to the empty list. The server doesn't 3765 implement the KOI8-R charset. 3767 Example 5: 3768 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3769 NOT FROM "Smith" 3770 S: B282 OK SEARCH completed 3771 C: B283 SEARCH CHARSET KOI8-R (OR $ 1,3000:3021) TEXT {4} 3772 C: XXXX 3773 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3774 //After this command the saved result variable contains 3775 //no messages. A client that wants to reissue the B283 3776 //SEARCH command with another CHARSET would have to reissue 3777 //the B282 command as well. One possible workaround for 3778 //this is to include the desired CHARSET parameter 3779 //in the earliest SEARCH RETURN (SAVE) command in a 3780 //sequence of related SEARCH commands. 3781 //A better approach might be to always use CHARSET UTF-8 3782 //instead. 3784 Note: Since this document format is restricted to 7-bit ASCII text, 3785 it is not possible to show actual KOI8-R data. The "XXXX" is a 3786 placeholder for what would be 4 octets of 8-bit data in an actual 3787 transaction. 3789 5) The following example demonstrates that it is not an error to use 3790 the "$" marker when it contains no messages. 3792 Example 6: 3793 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3794 NOT FROM "Eric" 3795 C: E283 COPY $ "Other Messages" 3796 //The "$" contains no messages 3797 S: E282 OK SEARCH completed 3798 S: E283 OK COPY completed, nothing copied 3800 Example 7: 3801 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3802 C: F283 COPY $ "Junk" 3803 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3804 S: F282 OK SEARCH completed 3805 S: F283 OK COPY completed 3806 S: F284 OK STORE completed 3808 Example 8: 3809 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3810 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3811 FROM "Eric" 3812 // The server can execute the two SEARCH commands 3813 // in any order, as they don't have any dependency. 3814 // For example, it may return: 3815 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3816 S: G283 OK SEARCH completed 3817 S: G282 OK SEARCH completed 3819 The following example demonstrates that the result of the second 3820 SEARCH RETURN (SAVE) always overrides the result of the first. 3822 Example 9: 3823 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3824 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3825 FROM "Eric" 3826 S: H282 OK SEARCH completed 3827 S: H283 OK SEARCH completed 3828 // At this point "$" would contain results of H283 3830 The following example demonstrates behavioral difference for 3831 different combinations of ESEARCH result options. Explanatory 3832 comments start with // and are not part of the protocol: 3834 Example 10: 3835 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3836 NOT FROM "Smith" 3837 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3838 //$ value hasn't changed 3839 S: C282 OK SEARCH completed 3841 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3842 NOT FROM "Smith" 3843 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3844 //$ value is 2,10:15,21 3845 S: C283 OK SEARCH completed 3847 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 3848 NOT FROM "Smith" 3849 S: * ESEARCH (TAG "C284") MIN 2 3850 //$ value is 2 3851 S: C284 OK SEARCH completed 3853 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 3854 12-Feb-2006 NOT FROM "Smith" 3855 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 3856 //$ value is 2,21 3857 S: C285 OK SEARCH completed 3859 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 3860 SINCE 12-Feb-2006 NOT FROM "Smith" 3861 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 3862 //$ value is 2,10:15,21 3863 S: C286 OK SEARCH completed 3865 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 3866 12-Feb-2006 NOT FROM "Smith" 3867 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 3868 //$ value is 2,10:15,21 3869 S: C286 OK SEARCH completed 3871 6.4.5. FETCH Command 3873 Arguments: sequence set 3874 message data item names or macro 3876 Responses: untagged responses: FETCH 3878 Result: OK - fetch completed 3879 NO - fetch error: can't fetch that data 3880 BAD - command unknown or arguments invalid 3882 The FETCH command retrieves data associated with a message in the 3883 mailbox. The data items to be fetched can be either a single atom or 3884 a parenthesized list. 3886 Most data items, identified in the formal syntax under the msg-att- 3887 static rule, are static and MUST NOT change for any particular 3888 message. Other data items, identified in the formal syntax under the 3889 msg-att-dynamic rule, MAY change, either as a result of a STORE 3890 command or due to external events. 3892 For example, if a client receives an ENVELOPE for a message when 3893 it already knows the envelope, it can safely ignore the newly 3894 transmitted envelope. 3896 There are three macros which specify commonly-used sets of data 3897 items, and can be used instead of data items. A macro must be used 3898 by itself, and not in conjunction with other macros or data items. 3900 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 3902 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 3904 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 3905 BODY) 3907 The currently defined data items that can be fetched are: 3909 BINARY[]<> 3911 Requests that the specified section be transmitted after 3912 performing Content-Transfer-Encoding-related decoding. 3914 The argument, if present, requests that a subset of 3915 the data be returned. The semantics of a partial FETCH BINARY 3916 command are the same as for a partial FETCH BODY command, with 3917 the exception that the arguments refer to the DECODED 3918 section data. 3920 BINARY.PEEK[]<> An alternate form of 3921 BINARY[] that does not implicitly set the \Seen 3922 flag. 3924 BINARY.SIZE[] 3926 Requests the decoded size of the section (i.e., the size to 3927 expect in response to the corresponding FETCH BINARY request). 3929 Note: client authors are cautioned that this might be an 3930 expensive operation for some server implementations. 3931 Needlessly issuing this request could result in degraded 3932 performance due to servers having to calculate the value every 3933 time the request is issued. 3935 BODY Non-extensible form of BODYSTRUCTURE. 3937 BODY[
]<> 3939 The text of a particular body section. The section 3940 specification is a set of zero or more part specifiers 3941 delimited by periods. A part specifier is either a part number 3942 or one of the following: HEADER, HEADER.FIELDS, 3943 HEADER.FIELDS.NOT, MIME, and TEXT. An empty section 3944 specification refers to the entire message, including the 3945 header. 3947 Every message has at least one part number. Non-[MIME-IMB] 3948 messages, and non-multipart [MIME-IMB] messages with no 3949 encapsulated message, only have a part 1. 3951 Multipart messages are assigned consecutive part numbers, as 3952 they occur in the message. If a particular part is of type 3953 message or multipart, its parts MUST be indicated by a period 3954 followed by the part number within that nested multipart part. 3956 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested 3957 part numbers, referring to parts of the MESSAGE part's body. 3959 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 3960 specifiers can be the sole part specifier or can be prefixed by 3961 one or more numeric part specifiers, provided that the numeric 3962 part specifier refers to a part of type MESSAGE/RFC822 or 3963 MESSAGE/GLOBAL. The MIME part specifier MUST be prefixed by 3964 one or more numeric part specifiers. 3966 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part 3967 specifiers refer to the [RFC-5322] header of the message or of 3968 an encapsulated [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL 3969 message. HEADER.FIELDS and HEADER.FIELDS.NOT are followed by a 3970 list of field-name (as defined in [RFC-5322]) names, and return 3971 a subset of the header. The subset returned by HEADER.FIELDS 3972 contains only those header fields with a field-name that 3973 matches one of the names in the list; similarly, the subset 3974 returned by HEADER.FIELDS.NOT contains only the header fields 3975 with a non-matching field-name. The field-matching is ASCII 3976 range case-insensitive but otherwise exact. Subsetting does 3977 not exclude the [RFC-5322] delimiting blank line between the 3978 header and the body; the blank line is included in all header 3979 fetches, except in the case of a message which has no body and 3980 no blank line. 3982 The MIME part specifier refers to the [MIME-IMB] header for 3983 this part. 3985 The TEXT part specifier refers to the text body of the message, 3986 omitting the [RFC-5322] header. 3988 Here is an example of a complex message with some of its 3989 part specifiers: 3991 HEADER ([RFC-5322] header of the message) 3992 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 3993 1 TEXT/PLAIN 3994 2 APPLICATION/OCTET-STREAM 3995 3 MESSAGE/RFC822 3996 3.HEADER ([RFC-5322] header of the message) 3997 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 3998 3.1 TEXT/PLAIN 3999 3.2 APPLICATION/OCTET-STREAM 4000 4 MULTIPART/MIXED 4001 4.1 IMAGE/GIF 4002 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4003 4.2 MESSAGE/RFC822 4004 4.2.HEADER ([RFC-5322] header of the message) 4005 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4006 4.2.1 TEXT/PLAIN 4007 4.2.2 MULTIPART/ALTERNATIVE 4008 4.2.2.1 TEXT/PLAIN 4009 4.2.2.2 TEXT/RICHTEXT 4011 It is possible to fetch a substring of the designated text. 4012 This is done by appending an open angle bracket ("<"), the 4013 octet position of the first desired octet, a period, the 4014 maximum number of octets desired, and a close angle bracket 4015 (">") to the part specifier. If the starting octet is beyond 4016 the end of the text, an empty string is returned. 4018 Any partial fetch that attempts to read beyond the end of the 4019 text is truncated as appropriate. A partial fetch that starts 4020 at octet 0 is returned as a partial fetch, even if this 4021 truncation happened. 4023 Note: This means that BODY[]<0.2048> of a 1500-octet message 4024 will return BODY[]<0> with a literal of size 1500, not 4025 BODY[]. 4027 Note: A substring fetch of a HEADER.FIELDS or 4028 HEADER.FIELDS.NOT part specifier is calculated after 4029 subsetting the header. 4031 The \Seen flag is implicitly set; if this causes the flags to 4032 change, they SHOULD be included as part of the FETCH responses. 4034 BODY.PEEK[
]<> An alternate form of BODY[
] 4035 that does not implicitly set the \Seen flag. 4037 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4038 computed by the server by parsing the [MIME-IMB] header fields in 4039 the [RFC-5322] header and [MIME-IMB] headers. 4041 ENVELOPE The envelope structure of the message. This is computed by 4042 the server by parsing the [RFC-5322] header into the component 4043 parts, defaulting various fields as necessary. 4045 FLAGS The flags that are set for this message. 4047 INTERNALDATE The internal date of the message. 4049 RFC822.SIZE The [RFC-5322] size of the message. 4051 UID The unique identifier for the message. 4053 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4054 S: * 2 FETCH .... 4055 S: * 3 FETCH .... 4056 S: * 4 FETCH .... 4057 S: A654 OK FETCH completed 4059 6.4.6. STORE Command 4061 Arguments: sequence set 4062 message data item name 4063 value for message data item 4065 Responses: untagged responses: FETCH 4067 Result: OK - store completed 4068 NO - store error: can't store that data 4069 BAD - command unknown or arguments invalid 4071 The STORE command alters data associated with a message in the 4072 mailbox. Normally, STORE will return the updated value of the data 4073 with an untagged FETCH response. A suffix of ".SILENT" in the data 4074 item name prevents the untagged FETCH, and the server SHOULD assume 4075 that the client has determined the updated value itself or does not 4076 care about the updated value. 4078 Note: Regardless of whether or not the ".SILENT" suffix was used, 4079 the server SHOULD send an untagged FETCH response if a change to a 4080 message's flags from an external source is observed. The intent 4081 is that the status of the flags is determinate without a race 4082 condition. 4084 The currently defined data items that can be stored are: 4086 FLAGS Replace the flags for the message with the 4087 argument. The new value of the flags is returned as if a FETCH of 4088 those flags was done. 4090 FLAGS.SILENT Equivalent to FLAGS, but without returning 4091 a new value. 4093 +FLAGS Add the argument to the flags for the message. 4094 The new value of the flags is returned as if a FETCH of those 4095 flags was done. 4097 +FLAGS.SILENT Equivalent to +FLAGS, but without 4098 returning a new value. 4100 -FLAGS Remove the argument from the flags for the 4101 message. The new value of the flags is returned as if a FETCH of 4102 those flags was done. 4104 -FLAGS.SILENT Equivalent to -FLAGS, but without 4105 returning a new value. 4107 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4108 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4109 S: * 3 FETCH (FLAGS (\Deleted)) 4110 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4111 S: A003 OK STORE completed 4113 6.4.7. COPY Command 4115 Arguments: sequence set 4116 mailbox name 4118 Responses: no specific responses for this command 4119 Result: OK - copy completed 4120 NO - copy error: can't copy those messages or to that 4121 name 4122 BAD - command unknown or arguments invalid 4124 The COPY command copies the specified message(s) to the end of the 4125 specified destination mailbox. The flags and internal date of the 4126 message(s) SHOULD be preserved in the copy. 4128 If the destination mailbox does not exist, a server SHOULD return an 4129 error. It SHOULD NOT automatically create the mailbox. Unless it is 4130 certain that the destination mailbox can not be created, the server 4131 MUST send the response code "[TRYCREATE]" as the prefix of the text 4132 of the tagged NO response. This gives a hint to the client that it 4133 can attempt a CREATE command and retry the COPY if the CREATE is 4134 successful. 4136 If the COPY command is unsuccessful for any reason, server 4137 implementations MUST restore the destination mailbox to its state 4138 before the COPY attempt. 4140 On successful completion of a COPY, the server SHOULD return a 4141 COPYUID response code. 4143 In the case of a mailbox that has permissions set so that the client 4144 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4145 SHOULD NOT send an COPYUID response code as it would disclose 4146 information about the mailbox. 4148 In the case of a mailbox that has UIDNOTSTICKY status (see the 4149 UIDNOTSTICKY response code), the server MAY omit the COPYUID response 4150 code as it is not meaningful. 4152 If the server does not return the COPYUID response code, the client 4153 can discover this information by selecting the destination mailbox. 4154 The location of messages placed in the destination mailbox by COPY 4155 can be determined by using FETCH and/or SEARCH commands (e.g., for 4156 Message-ID). 4158 Example: C: A003 COPY 2:4 MEETING 4159 S: A003 OK COPY completed 4161 6.4.8. MOVE Command 4163 Arguments: sequence set 4164 mailbox name 4166 Responses: no specific responses for this command 4167 Result: OK - move completed 4168 NO - move error: can't move those messages or to that 4169 name 4170 BAD - command unknown or arguments invalid 4172 The MOVE command moves the specified message(s) to the end of the 4173 specified destination mailbox. The flags and internal date of the 4174 message(s) SHOULD be preserved. 4176 This means that a new message is created in the target mailbox with a 4177 new UID, the original message is removed from the source mailbox, and 4178 it appears to the client as a single action. This has the same 4179 effect for each message as this sequence: 4181 1. [UID] COPY 4183 2. [UID] STORE +FLAGS.SILENT \DELETED 4185 3. UID EXPUNGE 4187 Although the effect of the MOVE is the same as the preceding steps, 4188 the semantics are not identical: The intermediate states produced by 4189 those steps do not occur, and the response codes are different. In 4190 particular, though the COPY and EXPUNGE response codes will be 4191 returned, response codes for a STORE MUST NOT be generated and the 4192 \Deleted flag MUST NOT be set for any message. 4194 Because a MOVE applies to a set of messages, it might fail partway 4195 through the set. Regardless of whether the command is successful in 4196 moving the entire set, each individual message SHOULD either be moved 4197 or unaffected. The server MUST leave each message in a state where 4198 it is in at least one of the source or target mailboxes (no message 4199 can be lost or orphaned). The server SHOULD NOT leave any message in 4200 both mailboxes (it would be bad for a partial failure to result in a 4201 bunch of duplicate messages). This is true even if the server 4202 returns a tagged NO response to the command. 4204 Because of the similarity of MOVE to COPY, extensions that affect 4205 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4206 (see Section 7.1), as well as those defined by extensions, are sent 4207 as appropriate. 4209 Servers SHOULD send COPYUID in response to a UID MOVE (see 4210 Section 6.4.9) command. For additional information see Section 7.1. 4212 Servers are also advised to send the COPYUID response code in an 4213 untagged OK before sending EXPUNGE or moved responses. (Sending 4214 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4215 means that clients first receive an EXPUNGE for a message and 4216 afterwards COPYUID for the same message. It can be unnecessarily 4217 difficult to process that sequence usefully.) 4219 An example: 4220 C: a UID MOVE 42:69 foo 4221 S: * OK [COPYUID 432432 42:69 1202:1229] 4222 S: * 22 EXPUNGE 4223 S: (more expunges) 4224 S: a OK Done 4226 Note that the server may send unrelated EXPUNGE responses as well, if 4227 any happen to have been expunged at the same time; this is normal 4228 IMAP operation. 4230 Note that moving a message to the currently selected mailbox (that 4231 is, where the source and target mailboxes are the same) is allowed 4232 when copying the message to the currently selected mailbox is 4233 allowed. 4235 The server may send EXPUNGE responses before the tagged response, so 4236 the client cannot safely send more commands with message sequence 4237 number arguments while the server is processing MOVE. 4239 MOVE and UID MOVE can be pipelined with other commands, but care has 4240 to be taken. Both commands modify sequence numbers and also allow 4241 unrelated EXPUNGE responses. The renumbering of other messages in 4242 the source mailbox following any EXPUNGE response can be surprising 4243 and makes it unsafe to pipeline any command that relies on message 4244 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4245 pipelined with a command that might cause message renumbering. See 4246 Section 5.5, for more information about ambiguities as well as 4247 handling requirements for both clients and servers. 4249 6.4.9. UID Command 4251 Arguments: command name 4252 command arguments 4254 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4256 Result: OK - UID command completed 4257 NO - UID command error 4258 BAD - command unknown or arguments invalid 4260 The UID command has three forms. In the first form, it takes as its 4261 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4262 appropriate for the associated command. However, the numbers in the 4263 sequence set argument are unique identifiers instead of message 4264 sequence numbers. Sequence set ranges are permitted, but there is no 4265 guarantee that unique identifiers will be contiguous. 4267 A non-existent unique identifier is ignored without any error message 4268 generated. Thus, it is possible for a UID FETCH command to return an 4269 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4270 OK without performing any operations. 4272 In the second form, the UID command takes an EXPUNGE command with an 4273 extra parameter the specified a sequence set of UIDs to operate on. 4274 The UID EXPUNGE command permanently removes all messages that both 4275 have the \Deleted flag set and have a UID that is included in the 4276 specified sequence set from the currently selected mailbox. If a 4277 message either does not have the \Deleted flag set or has a UID that 4278 is not included in the specified sequence set, it is not affected. 4280 UID EXPUNGE is particularly useful for disconnected use clients. 4281 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4282 the server, the client can ensure that it does not inadvertantly 4283 remove any messages that have been marked as \Deleted by other 4284 clients between the time that the client was last connected and 4285 the time the client resynchronizes. 4287 Example: C: A003 UID EXPUNGE 3000:3002 4288 S: * 3 EXPUNGE 4289 S: * 3 EXPUNGE 4290 S: * 3 EXPUNGE 4291 S: A003 OK UID EXPUNGE completed 4293 In the third form, the UID command takes a SEARCH command with SEARCH 4294 command arguments. The interpretation of the arguments is the same 4295 as with SEARCH; however, the numbers returned in a ESEARCH response 4296 for a UID SEARCH command are unique identifiers instead of message 4297 sequence numbers. Also, the corresponding ESEARCH response MUST 4298 include the UID indicator. For example, the command UID SEARCH 1:100 4299 UID 443:557 returns the unique identifiers corresponding to the 4300 intersection of two sequence sets, the message sequence number range 4301 1:100 and the UID range 443:557. 4303 Note: in the above example, the UID range 443:557 appears. The 4304 same comment about a non-existent unique identifier being ignored 4305 without any error message also applies here. Hence, even if 4306 neither UID 443 or 557 exist, this range is valid and would 4307 include an existing UID 495. 4309 Also note that a UID range of 559:* always includes the UID of the 4310 last message in the mailbox, even if 559 is higher than any 4311 assigned UID value. This is because the contents of a range are 4312 independent of the order of the range endpoints. Thus, any UID 4313 range with * as one of the endpoints indicates at least one 4314 message (the message with the highest numbered UID), unless the 4315 mailbox is empty. 4317 The number after the "*" in an untagged FETCH or EXPUNGE response is 4318 always a message sequence number, not a unique identifier, even for a 4319 UID command response. However, server implementations MUST 4320 implicitly include the UID message data item as part of any FETCH 4321 response caused by a UID command, regardless of whether a UID was 4322 specified as a message data item to the FETCH. 4324 Note: The rule about including the UID message data item as part of a 4325 FETCH response primarily applies to the UID FETCH and UID STORE 4326 commands, including a UID FETCH command that does not include UID as 4327 a message data item. Although it is unlikely that the other UID 4328 commands will cause an untagged FETCH, this rule applies to these 4329 commands as well. 4331 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4332 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4333 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4334 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4335 S: A999 OK UID FETCH completed 4337 6.5. Client Commands - Experimental/Expansion 4339 6.5.1. X Command 4341 Arguments: implementation defined 4343 Responses: implementation defined 4345 Result: OK - command completed 4346 NO - failure 4347 BAD - command unknown or arguments invalid 4349 Any command prefixed with an X is an experimental command. Commands 4350 which are not part of this specification, a standard or standards- 4351 track revision of this specification, or an IESG-approved 4352 experimental protocol, MUST use the X prefix. 4354 Any added untagged responses issued by an experimental command MUST 4355 also be prefixed with an X. Server implementations MUST NOT send any 4356 such untagged responses, unless the client requested it by issuing 4357 the associated experimental command. 4359 Example: C: a441 CAPABILITY 4360 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4361 S: a441 OK CAPABILITY completed 4362 C: A442 XPIG-LATIN 4363 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4364 S: A442 OK XPIG-LATIN ompleted-cay 4366 7. Server Responses 4368 Server responses are in three forms: status responses, server data, 4369 and command continuation request. The information contained in a 4370 server response, identified by "Contents:" in the response 4371 descriptions below, is described by function, not by syntax. The 4372 precise syntax of server responses is described in the Formal Syntax 4373 section. 4375 The client MUST be prepared to accept any response at all times. 4377 Status responses can be tagged or untagged. Tagged status responses 4378 indicate the completion result (OK, NO, or BAD status) of a client 4379 command, and have a tag matching the command. 4381 Some status responses, and all server data, are untagged. An 4382 untagged response is indicated by the token "*" instead of a tag. 4383 Untagged status responses indicate server greeting, or server status 4384 that does not indicate the completion of a command (for example, an 4385 impending system shutdown alert). For historical reasons, untagged 4386 server data responses are also called "unsolicited data", although 4387 strictly speaking, only unilateral server data is truly 4388 "unsolicited". 4390 Certain server data MUST be recorded by the client when it is 4391 received; this is noted in the description of that data. Such data 4392 conveys critical information which affects the interpretation of all 4393 subsequent commands and responses (e.g., updates reflecting the 4394 creation or destruction of messages). 4396 Other server data SHOULD be recorded for later reference; if the 4397 client does not need to record the data, or if recording the data has 4398 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4399 in progress), the data SHOULD be ignored. 4401 An example of unilateral untagged server data occurs when the IMAP 4402 connection is in the selected state. In the selected state, the 4403 server checks the mailbox for new messages as part of command 4404 execution. Normally, this is part of the execution of every command; 4405 hence, a NOOP command suffices to check for new messages. If new 4406 messages are found, the server sends untagged EXISTS response 4407 reflecting the new size of the mailbox. Server implementations that 4408 offer multiple simultaneous access to the same mailbox SHOULD also 4409 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4410 another agent changes the state of any message flags or expunges any 4411 messages. 4413 Command continuation request responses use the token "+" instead of a 4414 tag. These responses are sent by the server to indicate acceptance 4415 of an incomplete client command and readiness for the remainder of 4416 the command. 4418 7.1. Server Responses - Status Responses 4420 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4421 can be tagged or untagged. PREAUTH and BYE are always untagged. 4423 Status responses MAY include an OPTIONAL "response code". A response 4424 code consists of data inside square brackets in the form of an atom, 4425 possibly followed by a space and arguments. The response code 4426 contains additional information or status codes for client software 4427 beyond the OK/NO/BAD condition, and are defined when there is a 4428 specific action that a client can take based upon the additional 4429 information. 4431 The currently defined response codes are: 4433 ALERT 4435 The human-readable text contains a special alert that MUST be 4436 presented to the user in a fashion that calls the user's 4437 attention to the message. 4439 ALREADYEXISTS 4441 The operation attempts to create something that already exists, 4442 such as when the CREATE or RENAME directories attempt to create 4443 a mailbox and there is already one of that name. 4445 C: o RENAME this that 4446 S: o NO [ALREADYEXISTS] Mailbox "that" already exists 4448 APPENDUID 4450 Followed by the UIDVALIDITY of the destination mailbox and the 4451 UID assigned to the appended message in the destination 4452 mailbox, indicates that the message has been appended to the 4453 destination mailbox with that UID. 4455 If the server also supports the [MULTIAPPEND] extension, and if 4456 multiple messages were appended in the APPEND command, then the 4457 second value is a UID set containing the UIDs assigned to the 4458 appended messages, in the order they were transmitted in the 4459 APPEND command. This UID set may not contain extraneous UIDs 4460 or the symbol "*". 4462 Note: the UID set form of the APPENDUID response code MUST 4463 NOT be used if only a single message was appended. In 4464 particular, a server MUST NOT send a range such as 123:123. 4465 This is because a client that does not support [MULTIAPPEND] 4466 expects only a single UID and not a UID set. 4468 UIDs are assigned in strictly ascending order in the mailbox 4469 (refer to Section 2.3.1.1); note that a range of 12:10 is 4470 exactly equivalent to 10:12 and refers to the sequence 4471 10,11,12. 4473 This response code is returned in a tagged OK response to the 4474 APPEND command. 4476 AUTHENTICATIONFAILED 4478 Authentication failed for some reason on which the server is 4479 unwilling to elaborate. Typically, this includes "unknown 4480 user" and "bad password". 4482 This is the same as not sending any response code, except that 4483 when a client sees AUTHENTICATIONFAILED, it knows that the 4484 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4485 trying the same login/password again later. 4487 C: b LOGIN "fred" "foo" 4488 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4490 AUTHORIZATIONFAILED 4492 Authentication succeeded in using the authentication identity, 4493 but the server cannot or will not allow the authentication 4494 identity to act as the requested authorization identity. This 4495 is only applicable when the authentication and authorization 4496 identities are different. 4498 C: c1 AUTHENTICATE PLAIN 4499 [...] 4500 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4501 C: c2 AUTHENTICATE PLAIN 4502 [...] 4503 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4505 BADCHARSET 4507 Optionally followed by a parenthesized list of charsets. A 4508 SEARCH failed because the given charset is not supported by 4509 this implementation. If the optional list of charsets is 4510 given, this lists the charsets that are supported by this 4511 implementation. 4513 CANNOT 4515 The operation violates some invariant of the server and can 4516 never succeed. 4518 C: l create "///////" 4519 S: l NO [CANNOT] Adjacent slashes are not supported 4521 CAPABILITY 4523 Followed by a list of capabilities. This can appear in the 4524 initial OK or PREAUTH response to transmit an initial 4525 capabilities list. It can also appear in tagged responses to 4526 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4527 a client to send a separate CAPABILITY command if it recognizes 4528 this response. 4530 CLIENTBUG 4532 The server has detected a client bug. This can accompany all 4533 of OK, NO, and BAD, depending on what the client bug is. 4535 C: k1 select "/archive/projects/experiment-iv" 4536 [...] 4537 S: k1 OK [READ-ONLY] Done 4538 C: k2 status "/archive/projects/experiment-iv" (messages) 4539 [...] 4540 S: k2 OK [CLIENTBUG] Done 4542 CLOSED 4544 The CLOSED response code has no parameters. A server return 4545 the CLOSED response code when the currently selected mailbox is 4546 closed implicitly using the SELECT/EXAMINE command on another 4547 mailbox. The CLOSED response code serves as a boundary between 4548 responses for the previously opened mailbox (which was closed) 4549 and the newly selected mailbox; all responses before the CLOSED 4550 response code relate to the mailbox that was closed, and all 4551 subsequent responses relate to the newly opened mailbox. 4553 There is no need to return the CLOSED response code on 4554 completion of the CLOSE or the UNSELECT command (or similar), 4555 whose purpose is to close the currently selected mailbox 4556 without opening a new one. 4558 The server MAY also return an unsolicited CLOSED response code 4559 when it wants to force the client to return to authenticated 4560 state. For example, the server can do that when the mailbox 4561 requires repairs or is deleted in another session. 4563 CONTACTADMIN 4565 The user should contact the system administrator or support 4566 desk. 4568 C: e login "fred" "foo" 4569 S: e OK [CONTACTADMIN] 4571 COPYUID 4573 Followed by the UIDVALIDITY of the destination mailbox, a UID 4574 set containing the UIDs of the message(s) in the source mailbox 4575 that were copied to the destination mailbox and containing the 4576 UIDs assigned to the copied message(s) in the destination 4577 mailbox, indicates that the message(s) have been copied to the 4578 destination mailbox with the stated UID(s). 4580 The source UID set is in the order the message(s) were copied; 4581 the destination UID set corresponds to the source UID set and 4582 is in the same order. Neither of the UID sets may contain 4583 extraneous UIDs or the symbol "*". 4585 UIDs are assigned in strictly ascending order in the mailbox 4586 (refer to Section 2.3.1.1); note that a range of 12:10 is 4587 exactly equivalent to 10:12 and refers to the sequence 4588 10,11,12. 4590 This response code is returned in a tagged OK response to the 4591 COPY command. 4593 CORRUPTION 4595 The server discovered that some relevant data (e.g., the 4596 mailbox) are corrupt. This response code does not include any 4597 information about what's corrupt, but the server can write that 4598 to its logfiles. 4600 C: i select "/archive/projects/experiment-iv" 4601 S: i NO [CORRUPTION] Cannot open mailbox 4603 EXPIRED 4605 Either authentication succeeded or the server no longer had the 4606 necessary data; either way, access is no longer permitted using 4607 that passphrase. The client or user should get a new 4608 passphrase. 4610 C: d login "fred" "foo" 4611 S: d NO [EXPIRED] That password isn't valid any more 4613 EXPUNGEISSUED 4615 Someone else has issued an EXPUNGE for the same mailbox. The 4616 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4617 discusses this subject in depth. 4619 C: h search from fred@example.com 4620 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4621 S: h OK [EXPUNGEISSUED] Search completed 4623 INUSE 4625 An operation has not been carried out because it involves 4626 sawing off a branch someone else is sitting on. Someone else 4627 may be holding an exclusive lock needed for this operation, or 4628 the operation may involve deleting a resource someone else is 4629 using, typically a mailbox. 4631 The operation may succeed if the client tries again later. 4633 C: g delete "/archive/projects/experiment-iv" 4634 S: g NO [INUSE] Mailbox in use 4636 LIMIT 4638 The operation ran up against an implementation limit of some 4639 kind, such as the number of flags on a single message or the 4640 number of flags used in a mailbox. 4642 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4643 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4645 NONEXISTENT 4647 The operation attempts to delete something that does not exist. 4648 Similar to ALREADYEXISTS. 4650 C: p RENAME this that 4651 S: p NO [NONEXISTENT] No such mailbox 4653 NOPERM 4655 The access control system (e.g., Access Control List (ACL), see 4656 [RFC4314] does not permit this user to carry out an operation, 4657 such as selecting or creating a mailbox. 4659 C: f select "/archive/projects/experiment-iv" 4660 S: f NO [NOPERM] Access denied 4662 OVERQUOTA 4664 The user would be over quota after the operation. (The user 4665 may or may not be over quota already.) 4667 Note that if the server sends OVERQUOTA but doesn't support the 4668 IMAP QUOTA extension defined by [RFC2087], then there is a 4669 quota, but the client cannot find out what the quota is. 4671 C: n1 uid copy 1:* oldmail 4672 S: n1 NO [OVERQUOTA] Sorry 4674 C: n2 uid copy 1:* oldmail 4675 S: n2 OK [OVERQUOTA] You are now over your soft quota 4677 PARSE 4679 The human-readable text represents an error in parsing the 4680 [RFC-5322] header or [MIME-IMB] headers of a message in the 4681 mailbox. 4683 PERMANENTFLAGS 4685 Followed by a parenthesized list of flags, indicates which of 4686 the known flags the client can change permanently. Any flags 4687 that are in the FLAGS untagged response, but not the 4688 PERMANENTFLAGS list, can not be set permanently. The 4689 PERMANENTFLAGS list can also include the special flag \*, which 4690 indicates that it is possible to create new keywords by 4691 attempting to store those keywords in the mailbox. If the 4692 client attempts to STORE a flag that is not in the 4693 PERMANENTFLAGS list, the server will either ignore the change 4694 or store the state change for the remainder of the current 4695 session only. 4697 There is no need for a server that included the special flag \* 4698 to return a new PERMANENTFLAGS response code when a new keyword 4699 was successfully set on a message upon client request. However 4700 if the server has a limit on the number of different keywords 4701 that can be stored in a mailbox and that limit is reached, the 4702 server MUST send a new PERMANENTFLAGS response code without the 4703 special flag \*. 4705 PRIVACYREQUIRED 4707 The operation is not permitted due to a lack of privacy. If 4708 Transport Layer Security (TLS) is not in use, the client could 4709 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4711 C: d login "fred" "foo" 4712 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4714 C: d select inbox 4715 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4717 READ-ONLY 4719 The mailbox is selected read-only, or its access while selected 4720 has changed from read-write to read-only. 4722 READ-WRITE 4724 The mailbox is selected read-write, or its access while 4725 selected has changed from read-only to read-write. 4727 SERVERBUG 4729 The server encountered a bug in itself or violated one of its 4730 own invariants. 4732 C: j select "/archive/projects/experiment-iv" 4733 S: j NO [SERVERBUG] This should not happen 4735 TRYCREATE 4737 An APPEND or COPY attempt is failing because the target mailbox 4738 does not exist (as opposed to some other reason). This is a 4739 hint to the client that the operation can succeed if the 4740 mailbox is first created by the CREATE command. 4742 UIDNEXT 4744 Followed by a decimal number, indicates the next unique 4745 identifier value. Refer to Section 2.3.1.1 for more 4746 information. 4748 UIDNOTSTICKY 4750 The selected mailbox is supported by a mail store that does not 4751 support persistent UIDs; that is, UIDVALIDITY will be different 4752 each time the mailbox is selected. Consequently, APPEND or 4753 COPY to this mailbox will not return an APPENDUID or COPYUID 4754 response code. 4756 This response code is returned in an untagged NO response to 4757 the SELECT command. 4759 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4760 This facility exists to support legacy mail stores in which 4761 it is technically infeasible to support persistent UIDs. 4762 This should be avoided when designing new mail stores. 4764 UIDVALIDITY 4766 Followed by a decimal number, indicates the unique identifier 4767 validity value. Refer to Section 2.3.1.1 for more information. 4769 UNAVAILABLE 4771 Temporary failure because a subsystem is down. For example, an 4772 IMAP server that uses a Lightweight Directory Access Protocol 4773 (LDAP) or Radius server for authentication might use this 4774 response code when the LDAP/Radius server is down. 4776 C: a LOGIN "fred" "foo" 4777 S: a NO [UNAVAILABLE] User's backend down for maintenance 4779 UNKNOWN-CTE 4781 The server does not know how to decode the section's Content- 4782 Transfer-Encoding. 4784 Additional response codes defined by particular client or server 4785 implementations SHOULD be prefixed with an "X" until they are added 4786 to a revision of this protocol. Client implementations SHOULD ignore 4787 response codes that they do not recognize. 4789 7.1.1. OK Response 4791 Contents: OPTIONAL response code 4792 human-readable text 4794 The OK response indicates an information message from the server. 4795 When tagged, it indicates successful completion of the associated 4796 command. The human-readable text MAY be presented to the user as an 4797 information message. The untagged form indicates an information-only 4798 message; the nature of the information MAY be indicated by a response 4799 code. 4801 The untagged form is also used as one of three possible greetings at 4802 connection startup. It indicates that the connection is not yet 4803 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4805 Example: S: * OK IMAP4rev2 server ready 4806 C: A001 LOGIN fred blurdybloop 4807 S: * OK [ALERT] System shutdown in 10 minutes 4808 S: A001 OK LOGIN Completed 4810 7.1.2. NO Response 4812 Contents: OPTIONAL response code 4813 human-readable text 4815 The NO response indicates an operational error message from the 4816 server. When tagged, it indicates unsuccessful completion of the 4817 associated command. The untagged form indicates a warning; the 4818 command can still complete successfully. The human-readable text 4819 describes the condition. 4821 Example: C: A222 COPY 1:2 owatagusiam 4822 S: * NO Disk is 98% full, please delete unnecessary data 4823 S: A222 OK COPY completed 4824 C: A223 COPY 3:200 blurdybloop 4825 S: * NO Disk is 98% full, please delete unnecessary data 4826 S: * NO Disk is 99% full, please delete unnecessary data 4827 S: A223 NO COPY failed: disk is full 4829 7.1.3. BAD Response 4831 Contents: OPTIONAL response code 4832 human-readable text 4834 The BAD response indicates an error message from the server. When 4835 tagged, it reports a protocol-level error in the client's command; 4836 the tag indicates the command that caused the error. The untagged 4837 form indicates a protocol-level error for which the associated 4838 command can not be determined; it can also indicate an internal 4839 server failure. The human-readable text describes the condition. 4841 Example: C: ...very long command line... 4842 S: * BAD Command line too long 4843 C: ...empty line... 4844 S: * BAD Empty command line 4845 C: A443 EXPUNGE 4846 S: * BAD Disk crash, attempting salvage to a new disk! 4847 S: * OK Salvage successful, no data lost 4848 S: A443 OK Expunge completed 4850 7.1.4. PREAUTH Response 4852 Contents: OPTIONAL response code 4853 human-readable text 4855 The PREAUTH response is always untagged, and is one of three possible 4856 greetings at connection startup. It indicates that the connection 4857 has already been authenticated by external means; thus no LOGIN/ 4858 AUTHENTICATE command is needed. 4860 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 4862 7.1.5. BYE Response 4864 Contents: OPTIONAL response code 4865 human-readable text 4867 The BYE response is always untagged, and indicates that the server is 4868 about to close the connection. The human-readable text MAY be 4869 displayed to the user in a status report by the client. The BYE 4870 response is sent under one of four conditions: 4872 1. as part of a normal logout sequence. The server will close the 4873 connection after sending the tagged OK response to the LOGOUT 4874 command. 4876 2. as a panic shutdown announcement. The server closes the 4877 connection immediately. 4879 3. as an announcement of an inactivity autologout. The server 4880 closes the connection immediately. 4882 4. as one of three possible greetings at connection startup, 4883 indicating that the server is not willing to accept a connection 4884 from this client. The server closes the connection immediately. 4886 The difference between a BYE that occurs as part of a normal LOGOUT 4887 sequence (the first case) and a BYE that occurs because of a failure 4888 (the other three cases) is that the connection closes immediately in 4889 the failure case. In all cases the client SHOULD continue to read 4890 response data from the server until the connection is closed; this 4891 will ensure that any pending untagged or completion responses are 4892 read and processed. 4894 Example: S: * BYE Autologout; idle for too long 4896 7.2. Server Responses - Server and Mailbox Status 4898 These responses are always untagged. This is how server and mailbox 4899 status data are transmitted from the server to the client. Many of 4900 these responses typically result from a command with the same name. 4902 7.2.1. The ENABLED Response 4904 Contents: capability listing 4906 The ENABLED response occurs as a result of an ENABLE command. The 4907 capability listing contains a space-separated listing of capability 4908 names that the server supports and that were successfully enabled. 4909 The ENABLED response may contain no capabilities, which means that no 4910 extensions listed by the client were successfully enabled. 4912 7.2.2. CAPABILITY Response 4914 Contents: capability listing 4916 The CAPABILITY response occurs as a result of a CAPABILITY command. 4917 The capability listing contains a space-separated listing of 4918 capability names that the server supports. The capability listing 4919 MUST include the atom "IMAP4rev2". 4921 In addition, client and server implementations MUST implement the 4922 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 4923 capabilities. See the Security Considerations section for important 4924 information. 4926 A capability name which begins with "AUTH=" indicates that the server 4927 supports that particular authentication mechanism. 4929 The LOGINDISABLED capability indicates that the LOGIN command is 4930 disabled, and that the server will respond with a tagged NO response 4931 to any attempt to use the LOGIN command even if the user name and 4932 password are valid. An IMAP client MUST NOT issue the LOGIN command 4933 if the server advertises the LOGINDISABLED capability. 4935 Other capability names indicate that the server supports an 4936 extension, revision, or amendment to the IMAP4rev2 protocol. Server 4937 responses MUST conform to this document until the client issues a 4938 command that uses the associated capability. 4940 Capability names MUST either begin with "X" or be standard or 4941 standards-track IMAP4rev2 extensions, revisions, or amendments 4942 registered with IANA. A server MUST NOT offer unregistered or non- 4943 standard capability names, unless such names are prefixed with an 4944 "X". 4946 Client implementations SHOULD NOT require any capability name other 4947 than "IMAP4rev2", and MUST ignore any unknown capability names. 4949 A server MAY send capabilities automatically, by using the CAPABILITY 4950 response code in the initial PREAUTH or OK responses, and by sending 4951 an updated CAPABILITY response code in the tagged OK response as part 4952 of a successful authentication. It is unnecessary for a client to 4953 send a separate CAPABILITY command if it recognizes these automatic 4954 capabilities. 4956 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 4958 7.2.3. LIST Response 4960 Contents: name attributes 4961 hierarchy delimiter 4962 name 4963 OPTIONAL extension data 4965 The LIST response occurs as a result of a LIST command. It returns a 4966 single name that matches the LIST specification. There can be 4967 multiple LIST responses for a single LIST command. 4969 The following base name attributes are defined: 4971 \NonExistent The "\NonExistent" attribute indicates that a mailbox 4972 name does not refer to an existing mailbox. Note that this 4973 attribute is not meaningful by itself, as mailbox names that match 4974 the canonical LIST pattern but don't exist must not be returned 4975 unless one of the two conditions listed below is also satisfied: 4977 1. The mailbox name also satisfies the selection criteria (for 4978 example, it is subscribed and the "SUBSCRIBED" selection 4979 option has been specified). 4981 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 4982 at least one descendant mailbox name that does not match the 4983 LIST pattern and does match the selection criteria. 4985 In practice, this means that the "\NonExistent" attribute is 4986 usually returned with one or more of "\Subscribed", "\Remote", 4987 "\HasChildren", or the CHILDINFO extended data item. 4989 The "\NonExistent" attribute implies "\NoSelect". 4991 \Noinferiors It is not possible for any child levels of hierarchy to 4992 exist under this name; no child levels exist now and none can be 4993 created in the future. 4995 \Noselect It is not possible to use this name as a selectable 4996 mailbox. 4998 \HasChildren The presence of this attribute indicates that the 4999 mailbox has child mailboxes. A server SHOULD NOT set this 5000 attribute if there are child mailboxes and the user does not have 5001 permission to access any of them. In this case, \HasNoChildren 5002 SHOULD be used. In many cases, however, a server may not be able 5003 to efficiently compute whether a user has access to any child 5004 mailbox. Note that even though the \HasChildren attribute for a 5005 mailbox must be correct at the time of processing of the mailbox, 5006 a client must be prepared to deal with a situation when a mailbox 5007 is marked with the \HasChildren attribute, but no child mailbox 5008 appears in the response to the LIST command. This might happen, 5009 for example, due to children mailboxes being deleted or made 5010 inaccessible to the user (using access control) by another client 5011 before the server is able to list them. 5013 \HasNoChildren The presence of this attribute indicates that the 5014 mailbox has NO child mailboxes that are accessible to the 5015 currently authenticated user. 5017 \Marked The mailbox has been marked "interesting" by the server; the 5018 mailbox probably contains messages that have been added since the 5019 last time the mailbox was selected. 5021 \Unmarked The mailbox does not contain any additional messages since 5022 the last time the mailbox was selected. 5024 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5025 command. 5027 \Remote The mailbox is a remote mailbox. 5029 It is an error for the server to return both a \HasChildren and a 5030 \HasNoChildren attribute in the same LIST response. 5032 Note: the \HasNoChildren attribute should not be confused with the 5033 \NoInferiors attribute, which indicates that no child mailboxes 5034 exist now and none can be created in the future. 5036 If it is not feasible for the server to determine whether or not the 5037 mailbox is "interesting", the server SHOULD NOT send either \Marked 5038 or \Unmarked. The server MUST NOT send more than one of \Marked, 5039 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5040 these. 5042 In addition to the base name attributes defined above, an IMAP server 5043 MAY also include any or all of the following attributes that denote 5044 "role" (or "special-use") of a mailbox. These attributes are 5045 included along with base attributes defined above. A given mailbox 5046 may have none, one, or more than one of these attributes. In some 5047 cases, a special use is advice to a client about what to put in that 5048 mailbox. In other cases, it's advice to a client about what to 5049 expect to find there. 5051 \All This mailbox presents all messages in the user's message store. 5052 Implementations MAY omit some messages, such as, perhaps, those in 5053 \Trash and \Junk. When this special use is supported, it is 5054 almost certain to represent a virtual mailbox. 5056 \Archive This mailbox is used to archive messages. The meaning of 5057 an "archival" mailbox is server-dependent; typically, it will be 5058 used to get messages out of the inbox, or otherwise keep them out 5059 of the user's way, while still making them accessible. 5061 \Drafts This mailbox is used to hold draft messages -- typically, 5062 messages that are being composed but have not yet been sent. In 5063 some server implementations, this might be a virtual mailbox, 5064 containing messages from other mailboxes that are marked with the 5065 "\Draft" message flag. Alternatively, this might just be advice 5066 that a client put drafts here. 5068 \Flagged This mailbox presents all messages marked in some way as 5069 "important". When this special use is supported, it is likely to 5070 represent a virtual mailbox collecting messages (from other 5071 mailboxes) that are marked with the "\Flagged" message flag. 5073 \Junk This mailbox is where messages deemed to be junk mail are 5074 held. Some server implementations might put messages here 5075 automatically. Alternatively, this might just be advice to a 5076 client-side spam filter. 5078 \Sent This mailbox is used to hold copies of messages that have been 5079 sent. Some server implementations might put messages here 5080 automatically. Alternatively, this might just be advice that a 5081 client save sent messages here. 5083 \Trash This mailbox is used to hold messages that have been deleted 5084 or marked for deletion. In some server implementations, this 5085 might be a virtual mailbox, containing messages from other 5086 mailboxes that are marked with the "\Deleted" message flag. 5087 Alternatively, this might just be advice that a client that 5088 chooses not to use the IMAP "\Deleted" model should use this as 5089 its trash location. In server implementations that strictly 5090 expect the IMAP "\Deleted" model, this special use is likely not 5091 to be supported. 5093 All of special-use attributes are OPTIONAL, and any given server or 5094 message store may support any combination of the attributes, or none 5095 at all. In most cases, there will likely be at most one mailbox with 5096 a given attribute for a given user, but in some server or message 5097 store implementations it might be possible for multiple mailboxes to 5098 have the same special-use attribute. 5100 Special-use attributes are likely to be user-specific. User Adam 5101 might share his \Sent mailbox with user Barb, but that mailbox is 5102 unlikely to also serve as Barb's \Sent mailbox. 5104 The hierarchy delimiter is a character used to delimit levels of 5105 hierarchy in a mailbox name. A client can use it to create child 5106 mailboxes, and to search higher or lower levels of naming hierarchy. 5107 All children of a top-level hierarchy node MUST use the same 5108 separator character. A NIL hierarchy delimiter means that no 5109 hierarchy exists; the name is a "flat" name. 5111 The name represents an unambiguous left-to-right hierarchy, and MUST 5112 be valid for use as a reference in LIST command. Unless \Noselect or 5113 \NonExistent is indicated, the name MUST also be valid as an argument 5114 for commands, such as SELECT, that accept mailbox names. 5116 The name might be followed by an OPTIONAL series of extended fields, 5117 a parenthesized list of tagged data (also referred to as "extended 5118 data item"). The first element of an extended field is a tag, which 5119 identifies the type of data. 5121 The server MAY return data in the extended fields that was not 5122 directly solicited by the client in the corresponding LIST command. 5123 For example, the client can enable extra extended fields by using 5124 another IMAP extension that make use of the extended LIST responses. 5125 The client MUST ignore all extended fields it doesn't recognize. 5127 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5129 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5130 ("color" "red")) Sample "text") 5131 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5132 Sample ("text" "more text")) 5134 7.2.4. NAMESPACE Response 5136 Contents: the prefix and hierarchy delimiter to the server's 5137 Personal Namespace(s), Other Users' Namespace(s), and 5138 Shared Namespace(s) 5140 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5141 contains the prefix and hierarchy delimiter to the server's Personal 5142 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5143 the server wishes to expose. The response will contain a NIL for any 5144 namespace class that is not available. Namespace-Response-Extensions 5145 ABNF non terminal is defined for extensibility and MAY be included in 5146 the response. 5148 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5150 7.2.5. STATUS Response 5152 Contents: name 5153 status parenthesized list 5155 The STATUS response occurs as a result of an STATUS command. It 5156 returns the mailbox name that matches the STATUS specification and 5157 the requested mailbox status information. 5159 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5161 7.2.6. ESEARCH Response 5163 Contents: one or more search-return-data pairs 5165 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5166 command. 5168 The ESEARCH response starts with an optional search correlator. If 5169 it is missing, then the response was not caused by a particular IMAP 5170 command, whereas if it is present, it contains the tag of the command 5171 that caused the response to be returned. 5173 The search correlator is followed by an optional UID indicator. If 5174 this indicator is present, all data in the ESEARCH response refers to 5175 UIDs, otherwise all returned data refers to message numbers. 5177 The rest of the ESEARCH response contains one or more search data 5178 pairs. Each pair starts with unique return item name, followed by a 5179 space and the corresponding data. Search data pairs may be returned 5180 in any order. Unless specified otherwise by an extension, any return 5181 item name SHOULD appear only once in an ESEARCH response. 5183 [[TBD: describe the most common search data pairs returned.]] 5185 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5187 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5189 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5191 7.2.7. FLAGS Response 5193 Contents: flag parenthesized list 5195 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5196 The flag parenthesized list identifies the flags (at a minimum, the 5197 system-defined flags) that are applicable for this mailbox. Flags 5198 other than the system flags can also exist, depending on server 5199 implementation. 5201 The update from the FLAGS response MUST be recorded by the client. 5203 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5205 7.3. Server Responses - Mailbox Size 5207 These responses are always untagged. This is how changes in the size 5208 of the mailbox are transmitted from the server to the client. 5209 Immediately following the "*" token is a number that represents a 5210 message count. 5212 7.3.1. EXISTS Response 5214 Contents: none 5216 The EXISTS response reports the number of messages in the mailbox. 5217 This response occurs as a result of a SELECT or EXAMINE command, and 5218 if the size of the mailbox changes (e.g., new messages). 5220 The update from the EXISTS response MUST be recorded by the client. 5222 Example: S: * 23 EXISTS 5224 7.4. Server Responses - Message Status 5226 These responses are always untagged. This is how message data are 5227 transmitted from the server to the client, often as a result of a 5228 command with the same name. Immediately following the "*" token is a 5229 number that represents a message sequence number. 5231 7.4.1. EXPUNGE Response 5233 Contents: none 5235 The EXPUNGE response reports that the specified message sequence 5236 number has been permanently removed from the mailbox. The message 5237 sequence number for each successive message in the mailbox is 5238 immediately decremented by 1, and this decrement is reflected in 5239 message sequence numbers in subsequent responses (including other 5240 untagged EXPUNGE responses). 5242 The EXPUNGE response also decrements the number of messages in the 5243 mailbox; it is not necessary to send an EXISTS response with the new 5244 value. 5246 As a result of the immediate decrement rule, message sequence numbers 5247 that appear in a set of successive EXPUNGE responses depend upon 5248 whether the messages are removed starting from lower numbers to 5249 higher numbers, or from higher numbers to lower numbers. For 5250 example, if the last 5 messages in a 9-message mailbox are expunged, 5251 a "lower to higher" server will send five untagged EXPUNGE responses 5252 for message sequence number 5, whereas a "higher to lower server" 5253 will send successive untagged EXPUNGE responses for message sequence 5254 numbers 9, 8, 7, 6, and 5. 5256 An EXPUNGE response MUST NOT be sent when no command is in progress, 5257 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5258 is necessary to prevent a loss of synchronization of message sequence 5259 numbers between client and server. A command is not "in progress" 5260 until the complete command has been received; in particular, a 5261 command is not "in progress" during the negotiation of command 5262 continuation. 5264 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5265 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5266 during a UID command. 5268 The update from the EXPUNGE response MUST be recorded by the client. 5270 Example: S: * 44 EXPUNGE 5272 7.4.2. FETCH Response 5274 Contents: message data 5276 The FETCH response returns data about a message to the client. The 5277 data are pairs of data item names and their values in parentheses. 5278 This response occurs as the result of a FETCH or STORE command, as 5279 well as by unilateral server decision (e.g., flag updates). 5281 The current data items are: 5283 BINARY[]<> 5285 An or expressing the content of the 5286 specified section after removing any Content-Transfer-Encoding- 5287 related encoding. If is present it refers to the 5288 offset within the DECODED section data. 5290 If the domain of the decoded data is "8bit" and the data does 5291 not contain the NUL octet, the server SHOULD return the data in 5292 a instead of a ; this allows the client to 5293 determine if the "8bit" data contains the NUL octet without 5294 having to explicitly scan the data stream for for NULs. 5296 Messaging clients and servers have been notoriously lax in 5297 their adherence to the Internet CRLF convention for terminating 5298 lines of textual data (text/* media types) in Internet 5299 protocols. When sending data in BINARY[...] FETCH data item, 5300 servers MUST ensure that textual line-oriented sections are 5301 always transmitted using the IMAP4 CRLF line termination 5302 syntax, regardless of the underlying storage representation of 5303 the data on the server. 5305 If the server does not know how to decode the section's 5306 Content-Transfer-Encoding, it MUST fail the request and issue a 5307 "NO" response that contains the "UNKNOWN-CTE" response code. 5309 BINARY.SIZE[] 5311 The size of the section after removing any Content-Transfer- 5312 Encoding-related encoding. The value returned MUST match the 5313 size of the or that will be returned by 5314 the corresponding FETCH BINARY request. 5316 If the server does not know how to decode the section's 5317 Content-Transfer-Encoding, it MUST fail the request and issue a 5318 "NO" response that contains the "UNKNOWN-CTE" response code. 5320 BODY A form of BODYSTRUCTURE without extension data. 5322 BODY[
]<> 5324 A string expressing the body contents of the specified section. 5325 The string SHOULD be interpreted by the client according to the 5326 content transfer encoding, body type, and subtype. 5328 If the origin octet is specified, this string is a substring of 5329 the entire body contents, starting at that origin octet. This 5330 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5331 truncated. 5333 Note: The origin octet facility MUST NOT be used by a server 5334 in a FETCH response unless the client specifically requested 5335 it by means of a FETCH of a BODY[
]<> data 5336 item. 5338 8-bit textual data is permitted if a [CHARSET] identifier is 5339 part of the body parameter parenthesized list for this section. 5340 Note that headers (part specifiers HEADER or MIME, or the 5341 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5342 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5343 line between the header and the body is not affected by header 5344 line subsetting; the blank line is always included as part of 5345 header data, except in the case of a message which has no body 5346 and no blank line. 5348 Non-textual data such as binary data MUST be transfer encoded 5349 into a textual form, such as BASE64, prior to being sent to the 5350 client. To derive the original binary data, the client MUST 5351 decode the transfer encoded string. 5353 BODYSTRUCTURE 5355 A parenthesized list that describes the [MIME-IMB] body 5356 structure of a message. This is computed by the server by 5357 parsing the [MIME-IMB] header fields, defaulting various fields 5358 as necessary. 5360 For example, a simple text message of 48 lines and 2279 octets 5361 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5362 ASCII") NIL NIL "7BIT" 2279 48) 5364 Multiple parts are indicated by parenthesis nesting. Instead 5365 of a body type as the first element of the parenthesized list, 5366 there is a sequence of one or more nested body structures. The 5367 second element of the parenthesized list is the multipart 5368 subtype (mixed, digest, parallel, alternative, etc.). 5370 For example, a two part message consisting of a text and a 5371 BASE64-encoded text attachment can have a body structure of: 5372 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5373 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5374 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5375 "BASE64" 4554 73) "MIXED") 5377 Extension data follows the multipart subtype. Extension data 5378 is never returned with the BODY fetch, but can be returned with 5379 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5380 the defined order. The extension data of a multipart body part 5381 are in the following order: 5383 body parameter parenthesized list A parenthesized list of 5384 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5385 "bar" is the value of "foo", and "rag" is the value of 5386 "baz"] as defined in [MIME-IMB]. 5388 body parameter parenthesized list Servers SHOULD decode 5389 parameter value continuations as described in [RFC2231], for 5390 example, if the message contains parameters "foo*0*" and 5391 "foo*1*", the server should RFC2231-decode them, concatenate 5392 and return the resulting value as "foo*". 5394 body disposition A parenthesized list, consisting of a 5395 disposition type string, followed by a parenthesized list of 5396 disposition attribute/value pairs as defined in 5397 [DISPOSITION]. Servers SHOULD decode parameter value 5398 continuations as described in [RFC2231]. 5400 body language A string or parenthesized list giving the body 5401 language value as defined in [LANGUAGE-TAGS]. 5403 body location A string giving the body content URI as defined 5404 in [LOCATION]. 5406 Any following extension data are not yet defined in this 5407 version of the protocol. Such extension data can consist of 5408 zero or more NILs, strings, numbers, or potentially nested 5409 parenthesized lists of such data. Client implementations that 5410 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5411 extension data. Server implementations MUST NOT send such 5412 extension data until it has been defined by a revision of this 5413 protocol. 5415 The basic fields of a non-multipart body part are in the 5416 following order: 5418 body type A string giving the content media type name as 5419 defined in [MIME-IMB]. 5421 body subtype A string giving the content subtype name as 5422 defined in [MIME-IMB]. 5424 body parameter parenthesized list A parenthesized list of 5425 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5426 "bar" is the value of "foo" and "rag" is the value of "baz"] 5427 as defined in [MIME-IMB]. 5429 body id A string giving the Content-ID header field value as 5430 defined in Section 7 of [MIME-IMB]. 5432 body description A string giving the Content-Description 5433 header field value as defined in Section 8 of [MIME-IMB]. 5435 body encoding A string giving the content transfer encoding as 5436 defined in Section 6 of [MIME-IMB]. 5438 body size A number giving the size of the body in octets. 5439 Note that this size is the size in its transfer encoding and 5440 not the resulting size after any decoding. 5442 A body type of type MESSAGE and subtype RFC822 contains, 5443 immediately after the basic fields, the envelope structure, 5444 body structure, and size in text lines of the encapsulated 5445 message. 5447 A body type of type TEXT contains, immediately after the basic 5448 fields, the size of the body in text lines. Note that this 5449 size is the size in its content transfer encoding and not the 5450 resulting size after any decoding. 5452 Extension data follows the basic fields and the type-specific 5453 fields listed above. Extension data is never returned with the 5454 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5455 Extension data, if present, MUST be in the defined order. 5457 The extension data of a non-multipart body part are in the 5458 following order: 5460 body MD5 A string giving the body MD5 value as defined in 5461 [MD5]. 5463 body disposition A parenthesized list with the same content 5464 and function as the body disposition for a multipart body 5465 part. 5467 body language A string or parenthesized list giving the body 5468 language value as defined in [LANGUAGE-TAGS]. 5470 body location A string giving the body content URI as defined 5471 in [LOCATION]. 5473 Any following extension data are not yet defined in this 5474 version of the protocol, and would be as described above under 5475 multipart extension data. 5477 ENVELOPE 5479 A parenthesized list that describes the envelope structure of a 5480 message. This is computed by the server by parsing the 5481 [RFC-5322] header into the component parts, defaulting various 5482 fields as necessary. 5484 The fields of the envelope structure are in the following 5485 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5486 reply-to, and message-id. The date, subject, in-reply-to, and 5487 message-id fields are strings. The from, sender, reply-to, to, 5488 cc, and bcc fields are parenthesized lists of address 5489 structures. 5491 An address structure is a parenthesized list that describes an 5492 electronic mail address. The fields of an address structure 5493 are in the following order: personal name, [SMTP] at-domain- 5494 list (source route), mailbox name, and host name. 5496 [RFC-5322] group syntax is indicated by a special form of 5497 address structure in which the host name field is NIL. If the 5498 mailbox name field is also NIL, this is an end of group marker 5499 (semi-colon in RFC 822 syntax). If the mailbox name field is 5500 non-NIL, this is a start of group marker, and the mailbox name 5501 field holds the group name phrase. 5503 If the Date, Subject, In-Reply-To, and Message-ID header lines 5504 are absent in the [RFC-5322] header, the corresponding member 5505 of the envelope is NIL; if these header lines are present but 5506 empty the corresponding member of the envelope is the empty 5507 string. 5509 Note: some servers may return a NIL envelope member in the 5510 "present but empty" case. Clients SHOULD treat NIL and 5511 empty string as identical. 5513 Note: [RFC-5322] requires that all messages have a valid 5514 Date header. Therefore, the date member in the envelope can 5515 not be NIL or the empty string. 5517 Note: [RFC-5322] requires that the In-Reply-To and Message- 5518 ID headers, if present, have non-empty content. Therefore, 5519 the in-reply-to and message-id members in the envelope can 5520 not be the empty string. 5522 If the From, To, Cc, and Bcc header lines are absent in the 5523 [RFC-5322] header, or are present but empty, the corresponding 5524 member of the envelope is NIL. 5526 If the Sender or Reply-To lines are absent in the [RFC-5322] 5527 header, or are present but empty, the server sets the 5528 corresponding member of the envelope to be the same value as 5529 the from member (the client is not expected to know to do 5530 this). 5532 Note: [RFC-5322] requires that all messages have a valid 5533 From header. Therefore, the from, sender, and reply-to 5534 members in the envelope can not be NIL. 5536 FLAGS A parenthesized list of flags that are set for this message. 5538 INTERNALDATE A string representing the internal date of the message. 5540 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5542 UID A number expressing the unique identifier of the message. 5544 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5546 7.5. Server Responses - Command Continuation Request 5548 The command continuation request response is indicated by a "+" token 5549 instead of a tag. This form of response indicates that the server is 5550 ready to accept the continuation of a command from the client. The 5551 remainder of this response is a line of text. 5553 This response is used in the AUTHENTICATE command to transmit server 5554 data to the client, and request additional client data. This 5555 response is also used if an argument to any command is a 5556 synchronizing literal. 5558 The client is not permitted to send the octets of the synchronizing 5559 literal unless the server indicates that it is expected. This 5560 permits the server to process commands and reject errors on a line- 5561 by-line basis. The remainder of the command, including the CRLF that 5562 terminates a command, follows the octets of the literal. If there 5563 are any additional command arguments, the literal octets are followed 5564 by a space and those arguments. 5566 Example: C: A001 LOGIN {11} 5567 S: + Ready for additional command text 5568 C: FRED FOOBAR {7} 5569 S: + Ready for additional command text 5570 C: fat man 5571 S: A001 OK LOGIN completed 5572 C: A044 BLURDYBLOOP {102856} 5573 S: A044 BAD No such command as "BLURDYBLOOP" 5575 8. Sample IMAP4rev2 connection 5577 The following is a transcript of an IMAP4rev2 connection. A long 5578 line in this sample is broken for editorial clarity. 5580 S: * OK IMAP4rev2 Service Ready 5581 C: a001 login mrc secret 5582 S: a001 OK LOGIN completed 5583 C: a002 select inbox 5584 S: * 18 EXISTS 5585 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5586 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5587 S: a002 OK [READ-WRITE] SELECT completed 5588 C: a003 fetch 12 full 5589 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5590 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5591 "IMAP4rev2 WG mtg summary and minutes" 5592 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5593 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5594 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5595 ((NIL NIL "imap" "cac.washington.edu")) 5596 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5597 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5598 "") 5599 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5600 92)) 5601 S: a003 OK FETCH completed 5602 C: a004 fetch 12 body[header] 5603 S: * 12 FETCH (BODY[HEADER] {342} 5604 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5605 S: From: Terry Gray 5606 S: Subject: IMAP4rev2 WG mtg summary and minutes 5607 S: To: imap@cac.washington.edu 5608 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5609 S: Message-Id: 5610 S: MIME-Version: 1.0 5611 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5612 S: 5613 S: ) 5614 S: a004 OK FETCH completed 5615 C: a005 store 12 +flags \deleted 5616 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5617 S: a005 OK +FLAGS completed 5618 C: a006 logout 5619 S: * BYE IMAP4rev2 server terminating connection 5620 S: a006 OK LOGOUT completed 5622 9. Formal Syntax 5624 The following syntax specification uses the Augmented Backus-Naur 5625 Form (ABNF) notation as specified in [ABNF]. 5627 In the case of alternative or optional rules in which a later rule 5628 overlaps an earlier rule, the rule which is listed earlier MUST take 5629 priority. For example, "\Seen" when parsed as a flag is the \Seen 5630 flag name and not a flag-extension, even though "\Seen" can be parsed 5631 as a flag-extension. Some, but not all, instances of this rule are 5632 noted below. 5634 Note: [ABNF] rules MUST be followed strictly; in particular: 5636 (1) Except as noted otherwise, all alphabetic characters are case- 5637 insensitive. The use of upper or lower case characters to define 5638 token strings is for editorial clarity only. Implementations MUST 5639 accept these strings in a case-insensitive fashion. 5641 (2) In all cases, SP refers to exactly one space. It is NOT 5642 permitted to substitute TAB, insert additional spaces, or 5643 otherwise treat SP as being equivalent to LWSP. 5645 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5647 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5648 addr-host ")" 5650 addr-adl = nstring 5651 ; Holds route from [RFC-5322] route-addr if 5652 ; non-NIL 5654 addr-host = nstring 5655 ; NIL indicates [RFC-5322] group syntax. 5656 ; Otherwise, holds [RFC-5322] domain name 5658 addr-mailbox = nstring 5659 ; NIL indicates end of [RFC-5322] group; if 5660 ; non-NIL and addr-host is NIL, holds 5661 ; [RFC-5322] group name. 5662 ; Otherwise, holds [RFC-5322] local-part 5663 ; after removing [RFC-5322] quoting 5665 addr-name = nstring 5666 ; If non-NIL, holds phrase from [RFC-5322] 5667 ; mailbox after removing [RFC-5322] quoting 5669 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5670 literal 5672 append-uid = uniqueid 5674 astring = 1*ASTRING-CHAR / string 5675 ASTRING-CHAR = ATOM-CHAR / resp-specials 5677 atom = 1*ATOM-CHAR 5679 ATOM-CHAR = 5681 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5682 quoted-specials / resp-specials 5684 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5685 *(CRLF base64) 5687 auth-type = atom 5688 ; Defined by [SASL] 5690 base64 = *(4base64-char) [base64-terminal] 5692 base64-char = ALPHA / DIGIT / "+" / "/" 5693 ; Case-sensitive 5695 base64-terminal = (2base64-char "==") / (3base64-char "=") 5697 body = "(" (body-type-1part / body-type-mpart) ")" 5699 body-extension = nstring / number / 5700 "(" body-extension *(SP body-extension) ")" 5701 ; Future expansion. Client implementations 5702 ; MUST accept body-extension fields. Server 5703 ; implementations MUST NOT generate 5704 ; body-extension fields except as defined by 5705 ; future standard or standards-track 5706 ; revisions of this specification. 5708 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5709 [SP body-fld-loc *(SP body-extension)]]] 5710 ; MUST NOT be returned on non-extensible 5711 ; "BODY" fetch 5713 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5714 [SP body-fld-loc *(SP body-extension)]]] 5715 ; MUST NOT be returned on non-extensible 5716 ; "BODY" fetch 5718 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5719 body-fld-enc SP body-fld-octets 5721 body-fld-desc = nstring 5722 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5724 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5725 "QUOTED-PRINTABLE") DQUOTE) / string 5727 body-fld-id = nstring 5729 body-fld-lang = nstring / "(" string *(SP string) ")" 5731 body-fld-loc = nstring 5733 body-fld-lines = number 5735 body-fld-md5 = nstring 5737 body-fld-octets = number 5739 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5741 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5742 [SP body-ext-1part] 5744 body-type-basic = media-basic SP body-fields 5745 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5747 body-type-mpart = 1*body SP media-subtype 5748 [SP body-ext-mpart] 5749 ; MULTIPART body part 5751 body-type-msg = media-message SP body-fields SP envelope 5752 SP body SP body-fld-lines 5754 body-type-text = media-text SP body-fields SP body-fld-lines 5756 capability = ("AUTH=" auth-type) / atom 5757 ; New capabilities MUST begin with "X" or be 5758 ; registered with IANA as standard or 5759 ; standards-track 5761 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5762 *(SP capability) 5763 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5764 ; and LOGINDISABLED capabilities 5765 ; Servers which offer RFC 1730 compatibility MUST 5766 ; list "IMAP4" as the first capability. 5768 CHAR8 = %x01-ff 5769 ; any OCTET except NUL, %x00 5771 charset = atom / quoted 5773 childinfo-extended-item = "CHILDINFO" SP "(" 5774 list-select-base-opt-quoted 5775 *(SP list-select-base-opt-quoted) ")" 5776 ; Extended data item (mbox-list-extended-item) 5777 ; returned when the RECURSIVEMATCH 5778 ; selection option is specified. 5779 ; Note 1: the CHILDINFO tag can be returned 5780 ; with and without surrounding quotes, as per 5781 ; mbox-list-extended-item-tag production. 5782 ; Note 2: The selection options are always returned 5783 ; quoted, unlike their specification in 5784 ; the extended LIST command. 5786 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5787 ; attributes for CHILDREN return option, at most one 5788 ; possible per LIST response 5790 command = tag SP (command-any / command-auth / command-nonauth / 5791 command-select) CRLF 5792 ; Modal based on state 5794 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / enable / x-command 5795 ; Valid in all states 5797 command-auth = append / create / delete / examine / list / 5798 Namespace-Command / 5799 rename / select / status / subscribe / unsubscribe / 5800 idle 5801 ; Valid only in Authenticated or Selected state 5803 command-nonauth = login / authenticate / "STARTTLS" 5804 ; Valid only when in Not Authenticated state 5806 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 5807 move / fetch / store / search / uid 5808 ; Valid only when in Selected state 5810 continue-req = "+" SP (resp-text / base64) CRLF 5812 copy = "COPY" SP sequence-set SP mailbox 5814 create = "CREATE" SP mailbox 5815 ; Use of INBOX gives a NO error 5817 date = date-text / DQUOTE date-text DQUOTE 5818 date-day = 1*2DIGIT 5819 ; Day of month 5821 date-day-fixed = (SP DIGIT) / 2DIGIT 5822 ; Fixed-format version of date-day 5824 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 5825 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 5827 date-text = date-day "-" date-month "-" date-year 5829 date-year = 4DIGIT 5831 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 5832 SP time SP zone DQUOTE 5834 delete = "DELETE" SP mailbox 5835 ; Use of INBOX gives a NO error 5837 digit-nz = %x31-39 5838 ; 1-9 5840 eitem-standard-tag = atom 5841 ; a tag for extended list data defined in a Standard 5842 ; Track or Experimental RFC. 5844 eitem-vendor-tag = vendor-token "-" atom 5845 ; a vendor-specific tag for extended list data 5847 enable = "ENABLE" 1*(SP capability) 5849 enable-data = "ENABLED" *(SP capability) 5851 envelope = "(" env-date SP env-subject SP env-from SP 5852 env-sender SP env-reply-to SP env-to SP env-cc SP 5853 env-bcc SP env-in-reply-to SP env-message-id ")" 5855 env-bcc = "(" 1*address ")" / nil 5857 env-cc = "(" 1*address ")" / nil 5859 env-date = nstring 5861 env-from = "(" 1*address ")" / nil 5863 env-in-reply-to = nstring 5865 env-message-id = nstring 5866 env-reply-to = "(" 1*address ")" / nil 5868 env-sender = "(" 1*address ")" / nil 5870 env-subject = nstring 5872 env-to = "(" 1*address ")" / nil 5874 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 5875 *(SP search-return-data) 5876 ; ESEARCH response replaces SEARCH response 5877 ; from IMAP4rev1. 5879 examine = "EXAMINE" SP mailbox 5881 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 5882 fetch-att / "(" fetch-att *(SP fetch-att) ")") 5884 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 5885 "RFC822.SIZE" / 5886 "BODY" ["STRUCTURE"] / "UID" / 5887 "BODY" section [partial] / 5888 "BODY.PEEK" section [partial] / 5889 "BINARY" [".PEEK"] section-binary [partial] / 5890 "BINARY.SIZE" section-binary 5892 flag = "\Answered" / "\Flagged" / "\Deleted" / 5893 "\Seen" / "\Draft" / flag-keyword / flag-extension 5894 ; Does not include "\Recent" 5896 flag-extension = "\" atom 5897 ; Future expansion. Client implementations 5898 ; MUST accept flag-extension flags. Server 5899 ; implementations MUST NOT generate 5900 ; flag-extension flags except as defined by 5901 ; future standard or standards-track 5902 ; revisions of this specification. 5903 ; "\Recent" was defined in RFC 3501 5904 ; and is now deprecated. 5906 flag-fetch = flag 5908 flag-keyword = "$MDNSent" / "$Forwarded" / atom 5910 flag-list = "(" [flag *(SP flag)] ")" 5912 flag-perm = flag / "\*" 5913 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 5915 header-fld-name = astring 5917 header-list = "(" header-fld-name *(SP header-fld-name) ")" 5919 idle = "IDLE" CRLF "DONE" 5921 initial-resp = (base64 / "=") 5922 ; "initial response" defined in 5923 ; Section 5.1 of [RFC4422] 5925 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 5926 [SP list-return-opts] 5928 list-mailbox = 1*list-char / string 5930 list-char = ATOM-CHAR / list-wildcards / resp-specials 5932 list-return-opts = "RETURN" SP 5933 "(" [return-option *(SP return-option)] ")" 5934 ; list return options, e.g., CHILDREN 5936 list-select-base-opt = "SUBSCRIBED" / option-extension 5937 ; options that can be used by themselves 5939 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 5941 list-select-independent-opt = "REMOTE" / option-extension 5942 ; options that do not syntactically interact with 5943 ; other options 5945 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 5946 ; options that require a list-select-base-opt 5947 ; to also be present 5949 list-select-opt = list-select-base-opt / list-select-independent-opt 5950 / list-select-mod-opt 5951 ; An option registration template is described in 5952 ; Section 9.3 of this document. 5954 list-select-opts = "(" [ 5955 (*(list-select-opt SP) list-select-base-opt 5956 *(SP list-select-opt)) 5957 / (list-select-independent-opt 5958 *(SP list-select-independent-opt)) 5959 ] ")" 5961 ; Any number of options may be in any order. 5962 ; If a list-select-mod-opt appears, then a 5963 ; list-select-base-opt must also appear. 5964 ; This allows these: 5965 ; () 5966 ; (REMOTE) 5967 ; (SUBSCRIBED) 5968 ; (SUBSCRIBED REMOTE) 5969 ; (SUBSCRIBED RECURSIVEMATCH) 5970 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 5971 ; But does NOT allow these: 5972 ; (RECURSIVEMATCH) 5973 ; (REMOTE RECURSIVEMATCH) 5975 list-wildcards = "%" / "*" 5977 literal = "{" number ["+"] "}" CRLF *CHAR8 5978 ; represents the number of CHAR8s. 5979 ; A non-synchronizing literal is distinguished from 5980 ; a synchronizing literal by presence of the "+" 5981 ; before the closing "}". 5982 ; Non synchronizing literals are not allowed when 5983 ; sent from server to the client. 5985 literal8 = "~{" number "}" CRLF *OCTET 5986 ; represents the number of OCTETs 5987 ; in the response string. 5989 login = "LOGIN" SP userid SP password 5991 mailbox = "INBOX" / astring 5992 ; INBOX is case-insensitive. All case variants of 5993 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 5994 ; not as an astring. An astring which consists of 5995 ; the case-insensitive sequence "I" "N" "B" "O" "X" 5996 ; is considered to be INBOX and not an astring. 5997 ; Refer to section 5.1 for further 5998 ; semantic details of mailbox names. 6000 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6001 esearch-response / 6002 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6003 number SP "EXISTS" / Namespace-Response 6005 mailbox-list = "(" [mbx-list-flags] ")" SP 6006 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6007 [SP mbox-list-extended] 6008 ; This is the list information pointed to by the ABNF 6009 ; item "mailbox-data", which is defined in [IMAP4] 6011 mbox-list-extended = "(" [mbox-list-extended-item 6012 *(SP mbox-list-extended-item)] ")" 6014 mbox-list-extended-item = mbox-list-extended-item-tag SP 6015 tagged-ext-val 6017 mbox-list-extended-item-tag = astring 6018 ; The content MUST conform to either "eitem-vendor-tag" 6019 ; or "eitem-standard-tag" ABNF productions. 6021 mbox-or-pat = list-mailbox / patterns 6023 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6024 *(SP mbx-list-oflag) / 6025 mbx-list-oflag *(SP mbx-list-oflag) 6027 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6028 "\Subscribed" / "\Remote" / flag-extension 6029 ; Other flags; multiple possible per LIST response 6031 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6032 ; Selectability flags; only one per LIST response 6034 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6035 "MESSAGE" / "VIDEO" / "FONT") DQUOTE) / string) SP 6036 media-subtype 6037 ; Defined in [MIME-IMT]. 6038 ; FONT defined in RFC YYYY. 6040 media-message = DQUOTE "MESSAGE" DQUOTE SP 6041 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6042 ; Defined in [MIME-IMT] 6044 media-subtype = string 6045 ; Defined in [MIME-IMT] 6047 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6048 ; Defined in [MIME-IMT] 6050 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6052 move = "MOVE" SP sequence-set SP mailbox 6054 msg-att = "(" (msg-att-dynamic / msg-att-static) 6055 *(SP (msg-att-dynamic / msg-att-static)) ")" 6057 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6058 ; MAY change for a message 6060 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6061 "RFC822.SIZE" SP number / 6062 "BODY" ["STRUCTURE"] SP body / 6063 "BODY" section ["<" number ">"] SP nstring / 6064 "BINARY" section-binary SP (nstring / literal8) / 6065 "BINARY.SIZE" section-binary SP number / 6066 "UID" SP uniqueid 6067 ; MUST NOT change for a message 6069 Namespace = nil / "(" 1*Namespace-Descr ")" 6071 Namespace-Command = "NAMESPACE" 6073 Namespace-Descr = "(" string SP 6074 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6075 [Namespace-Response-Extensions] ")" 6077 Namespace-Response-Extensions = *(Namespace-Response-Extension) 6079 Namespace-Response-Extension = SP string SP 6080 "(" string *(SP string) ")" 6082 Namespace-Response = "NAMESPACE" SP Namespace 6083 SP Namespace SP Namespace 6084 ; The first Namespace is the Personal Namespace(s). 6085 ; The second Namespace is the Other Users' 6086 ; Namespace(s). 6087 ; The third Namespace is the Shared Namespace(s). 6089 nil = "NIL" 6091 nstring = string / nil 6093 number = 1*DIGIT 6094 ; Unsigned 32-bit integer 6095 ; (0 <= n < 4,294,967,296) 6097 number64 = 1*DIGIT 6098 ; Unsigned 63-bit integer 6099 ; (0 <= n <= 9,223,372,036,854,775,807) 6101 nz-number = digit-nz *DIGIT 6102 ; Non-zero unsigned 32-bit integer 6103 ; (0 < n < 4,294,967,296) 6105 option-extension = (option-standard-tag / option-vendor-tag) 6106 [SP option-value] 6108 option-standard-tag = atom 6109 ; an option defined in a Standards Track or 6110 ; Experimental RFC 6112 option-val-comp = astring / 6113 option-val-comp *(SP option-val-comp) / 6114 "(" option-val-comp ")" 6116 option-value = "(" option-val-comp ")" 6118 option-vendor-tag = vendor-token "-" atom 6119 ; a vendor-specific option, non-standard 6121 partial-range = number ["." nz-number] 6122 ; Copied from RFC 5092 (IMAP URL) 6124 partial = "<" number "." nz-number ">" 6125 ; Partial FETCH request. 0-based offset of 6126 ; the first octet, followed by the number of octets 6127 ; in the fragment. 6129 password = astring 6131 patterns = "(" list-mailbox *(SP list-mailbox) ")" 6133 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6135 QUOTED-CHAR = / 6136 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6138 quoted-specials = DQUOTE / "\" 6140 rename = "RENAME" SP mailbox SP mailbox 6141 ; Use of INBOX as a destination gives a NO error 6143 response = *(continue-req / response-data) response-done 6145 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6146 mailbox-data / message-data / capability-data / 6147 enable-data) CRLF 6149 response-done = response-tagged / response-fatal 6151 response-fatal = "*" SP resp-cond-bye CRLF 6152 ; Server closes connection immediately 6154 response-tagged = tag SP resp-cond-state CRLF 6156 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6158 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6160 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6161 ; Authentication condition 6163 resp-cond-bye = "BYE" SP resp-text 6165 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6166 ; Status condition 6168 resp-specials = "]" 6170 resp-text = ["[" resp-text-code "]" SP] [text] 6172 resp-text-code = "ALERT" / 6173 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6174 capability-data / "PARSE" / 6175 "PERMANENTFLAGS" SP "(" 6176 [flag-perm *(SP flag-perm)] ")" / 6177 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6178 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6179 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6180 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6181 "AUTHORIZATIONFAILED" / "EXPIRED" / 6182 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6183 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6184 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6185 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6186 "NONEXISTENT" / "NOTSAVED" / 6187 "CLOSED" / 6188 "UNKNOWN-CTE" / 6189 atom [SP 1*] 6191 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6192 option-extension 6194 search = "SEARCH" [search-return-opts] 6195 SP search-program 6197 search-correlator = SP "(" "TAG" SP tag-string ")" 6199 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6200 "BEFORE" SP date / "BODY" SP astring / 6201 "CC" SP astring / "DELETED" / "FLAGGED" / 6202 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6203 "ON" SP date / "SEEN" / 6204 "SINCE" SP date / "SUBJECT" SP astring / 6205 "TEXT" SP astring / "TO" SP astring / 6206 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6207 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6208 ; Above this line were in [IMAP2] 6209 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6210 "LARGER" SP number / "NOT" SP search-key / 6211 "OR" SP search-key SP search-key / 6212 "SENTBEFORE" SP date / "SENTON" SP date / 6213 "SENTSINCE" SP date / "SMALLER" SP number / 6214 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6215 "(" search-key *(SP search-key) ")" 6217 search-modifier-name = tagged-ext-label 6219 search-mod-params = tagged-ext-val 6220 ; This non-terminal shows recommended syntax 6221 ; for future extensions. 6223 search-program = ["CHARSET" SP charset SP] 6224 search-key *(SP search-key) 6225 ; CHARSET argument to SEARCH MUST be 6226 ; registered with IANA. 6228 search-ret-data-ext = search-modifier-name SP search-return-value 6229 ; Note that not every SEARCH return option 6230 ; is required to have the corresponding 6231 ; ESEARCH return data. 6233 search-return-data = "MIN" SP nz-number / 6234 "MAX" SP nz-number / 6235 "ALL" SP sequence-set / 6236 "COUNT" SP number / 6237 search-ret-data-ext 6238 ; All return data items conform to 6239 ; search-ret-data-ext syntax. 6240 ; Note that "$" marker is not allowed 6241 ; after the ALL return data item. 6243 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6244 *(SP search-return-opt)] ")" 6246 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6247 "SAVE" / 6248 search-ret-opt-ext 6249 ; conforms to generic search-ret-opt-ext 6250 ; syntax 6252 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6254 search-return-value = tagged-ext-val 6255 ; Data for the returned search option. 6256 ; A single "nz-number"/"number"/"number64" value 6257 ; can be returned as an atom (i.e., without 6258 ; quoting). A sequence-set can be returned 6259 ; as an atom as well. 6261 section = "[" [section-spec] "]" 6263 section-binary = "[" [section-part] "]" 6265 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6266 "TEXT" 6267 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6269 section-part = nz-number *("." nz-number) 6270 ; body part reference. 6271 ; Allows for accessing nested body parts. 6273 section-spec = section-msgtext / (section-part ["." section-text]) 6275 section-text = section-msgtext / "MIME" 6276 ; text other than actual body part (headers, etc.) 6278 select = "SELECT" SP mailbox 6280 seq-number = nz-number / "*" 6281 ; message sequence number (COPY, FETCH, STORE 6282 ; commands) or unique identifier (UID COPY, 6283 ; UID FETCH, UID STORE commands). 6284 ; * represents the largest number in use. In 6285 ; the case of message sequence numbers, it is 6286 ; the number of messages in a non-empty mailbox. 6287 ; In the case of unique identifiers, it is the 6288 ; unique identifier of the last message in the 6289 ; mailbox or, if the mailbox is empty, the 6290 ; mailbox's current UIDNEXT value. 6291 ; The server should respond with a tagged BAD 6292 ; response to a command that uses a message 6293 ; sequence number greater than the number of 6294 ; messages in the selected mailbox. This 6295 ; includes "*" if the selected mailbox is empty. 6297 seq-range = seq-number ":" seq-number 6298 ; two seq-number values and all values between 6299 ; these two regardless of order. 6300 ; Example: 2:4 and 4:2 are equivalent and indicate 6301 ; values 2, 3, and 4. 6302 ; Example: a unique identifier sequence range of 6303 ; 3291:* includes the UID of the last message in 6304 ; the mailbox, even if that value is less than 3291. 6306 sequence-set = (seq-number / seq-range) ["," sequence-set] 6307 ; set of seq-number values, regardless of order. 6308 ; Servers MAY coalesce overlaps and/or execute the 6309 ; sequence in any order. 6310 ; Example: a message sequence number set of 6311 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6312 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6313 ; Example: a message sequence number set of *:4,5:7 6314 ; for a mailbox with 10 messages is equivalent to 6315 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6316 ; overlap coalesced to be 4,5,6,7,8,9,10. 6318 sequence-set =/ seq-last-command 6319 ; Allow for "result of the last command" indicator. 6321 seq-last-command = "$" 6323 status = "STATUS" SP mailbox SP 6324 "(" status-att *(SP status-att) ")" 6326 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6327 "UNSEEN" / "DELETED" / "SIZE" 6329 status-att-val = ("MESSAGES" SP number) / 6330 ("UIDNEXT" SP nz-number) / 6331 ("UIDVALIDITY" SP nz-number) / 6332 ("UNSEEN" SP number) / 6333 ("DELETED" SP number) / 6334 ("SIZE" SP number64) 6335 ; Extensions to the STATUS responses 6336 ; should extend this production. 6337 ; Extensions should use the generic 6338 ; syntax defined by tagged-ext. 6340 status-att-list = status-att-val *(SP status-att-val) 6342 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6343 ; This ABNF production complies with 6344 ; syntax. 6346 store = "STORE" SP sequence-set SP store-att-flags 6348 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6349 (flag-list / (flag *(SP flag))) 6351 string = quoted / literal 6353 subscribe = "SUBSCRIBE" SP mailbox 6355 tag = 1* 6357 tagged-ext-label = tagged-label-fchar *tagged-label-char 6358 ;; Is a valid RFC 3501 "atom". 6360 tagged-label-fchar = ALPHA / "-" / "_" / "." 6362 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6364 tagged-ext-comp = astring / 6365 tagged-ext-comp *(SP tagged-ext-comp) / 6366 "(" tagged-ext-comp ")" 6367 ;; Extensions that follow this general 6368 ;; syntax should use nstring instead of 6369 ;; astring when appropriate in the context 6370 ;; of the extension. 6371 ;; Note that a message set or a "number" 6372 ;; can always be represented as an "atom". 6373 ;; An URL should be represented as 6374 ;; a "quoted" string. 6376 tagged-ext-simple = sequence-set / number / number64 6378 tagged-ext-val = tagged-ext-simple / 6379 "(" [tagged-ext-comp] ")" 6381 text = 1*TEXT-CHAR 6383 TEXT-CHAR = 6385 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6386 ; Hours minutes seconds 6388 uid = "UID" SP 6389 (copy / move / fetch / search / store / uid-expunge) 6390 ; Unique identifiers used instead of message 6391 ; sequence numbers 6393 uid-expunge = "EXPUNGE" SP sequence-set 6394 ; Unique identifiers used instead of message 6395 ; sequence numbers 6397 uid-set = (uniqueid / uid-range) *("," uid-set) 6399 uid-range = (uniqueid ":" uniqueid) 6400 ; two uniqueid values and all values 6401 ; between these two regards of order. 6402 ; Example: 2:4 and 4:2 are equivalent. 6404 uniqueid = nz-number 6405 ; Strictly ascending 6407 unsubscribe = "UNSUBSCRIBE" SP mailbox 6409 userid = astring 6411 UTF8-2 = 6413 UTF8-3 = 6415 UTF8-4 = 6417 x-command = "X" atom 6419 zone = ("+" / "-") 4DIGIT 6420 ; Signed four-digit value of hhmm representing 6421 ; hours and minutes east of Greenwich (that is, 6422 ; the amount that the given time differs from 6423 ; Universal Time). Subtracting the timezone 6424 ; from the given time will give the UT form. 6425 ; The Universal Time zone is "+0000". 6427 10. Author's Note 6429 This document is a revision or rewrite of earlier documents, and 6430 supercedes the protocol specification in those documents: RFC 2060, 6431 RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and RFC 1064. 6433 11. Security Considerations 6435 IMAP4rev2 protocol transactions, including electronic mail data, are 6436 sent in the clear over the network unless protection from snooping is 6437 negotiated. This can be accomplished either by the use of IMAPS 6438 service, STARTTLS command, negotiated privacy protection in the 6439 AUTHENTICATE command, or some other protection mechanism. 6441 11.1. STARTTLS Security Considerations 6443 IMAP client and server implementations MUST comply with relevant TLS 6444 recommendations from [RFC8314]. 6446 Additionally, when using TLS 1.2, IMAP implementations MUST implement 6447 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6448 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS] cipher suite. This 6449 is important as it assures that any two compliant implementations can 6450 be configured to interoperate. Other TLS cipher suites recommended 6451 in RFC 7525 are RECOMMENDED: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6452 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6453 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6454 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6456 During the [TLS] negotiation, the client MUST check its understanding 6457 of the server hostname against the server's identity as presented in 6458 the server Certificate message, in order to prevent man-in-the-middle 6459 attacks. This procedure is described in [RFC7817]. 6461 Both the client and server MUST check the result of the STARTTLS 6462 command and subsequent [TLS] negotiation to see whether acceptable 6463 authentication and/or privacy was achieved. 6465 11.2. COPYUID and APPENDUID response codes 6467 The COPYUID and APPENDUID response codes return information about the 6468 mailbox, which may be considered sensitive if the mailbox has 6469 permissions set that permit the client to COPY or APPEND to the 6470 mailbox, but not SELECT or EXAMINE it. 6472 Consequently, these response codes SHOULD NOT be issued if the client 6473 does not have access to SELECT or EXAMINE the mailbox. 6475 11.3. LIST command and Other Users' namespace 6477 In response to a LIST command containing an argument of the Other 6478 Users' Namespace prefix, a server SHOULD NOT list users that have not 6479 granted list access to their personal mailboxes to the currently 6480 authenticated user. Providing such a list, could compromise security 6481 by potentially disclosing confidential information of who is located 6482 on the server, or providing a starting point of a list of user 6483 accounts to attack. 6485 11.4. Other Security Considerations 6487 A server error message for an AUTHENTICATE command which fails due to 6488 invalid credentials SHOULD NOT detail why the credentials are 6489 invalid. 6491 Use of the LOGIN command sends passwords in the clear. This can be 6492 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6493 that does not use plaintext passwords, by first negotiating 6494 encryption via STARTTLS or some other protection mechanism. 6496 A server implementation MUST implement a configuration that, at the 6497 time of authentication, requires: 6498 (1) The STARTTLS command has been negotiated. 6499 OR 6500 (2) Some other mechanism that protects the session from password 6501 snooping has been provided. 6502 OR 6503 (3) The following measures are in place: 6504 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6505 (such as PLAIN) using plaintext passwords are NOT advertised in the 6506 CAPABILITY list. 6507 AND 6508 (b) The LOGIN command returns an error even if the password is 6509 correct. 6510 AND 6511 (c) The AUTHENTICATE command returns an error with all [SASL] 6512 mechanisms that use plaintext passwords, even if the password is 6513 correct. 6515 A server error message for a failing LOGIN command SHOULD NOT specify 6516 that the user name, as opposed to the password, is invalid. 6518 A server SHOULD have mechanisms in place to limit or delay failed 6519 AUTHENTICATE/LOGIN attempts. 6521 Additional security considerations are discussed in the section 6522 discussing the AUTHENTICATE and LOGIN commands. 6524 12. IANA Considerations 6526 IANA is requested to update "Service Names and Transport Protocol 6527 Port Numbers" registry as follows: 6529 1. Registration for TCP "imap" port 143 should be updated to point 6530 to this document and RFC 3501. 6532 2. Registration for TCP "imaps" port 993 should be updated to point 6533 to this document, RFC 8314 and RFC 3501. 6535 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6536 in the registry. 6538 Additional IANA actions are specified in subsection of this section. 6540 12.1. Updates to IMAP4 Capabilities registry 6542 IMAP4 capabilities are registered by publishing a standards track or 6543 IESG approved informational or experimental RFC. The registry is 6544 currently located at: http://www.iana.org/assignments/ 6545 imap4-capabilities 6547 As this specification revises the STARTTLS and LOGINDISABLED 6548 extensions previously defined in [IMAP-TLS], IANA is requested to 6549 update registry entries for these 2 extensions to point to this 6550 document. 6552 12.2. GSSAPI/SASL service name 6554 GSSAPI/Kerberos/SASL service names are registered by publishing a 6555 standards track or IESG approved experimental RFC. The registry is 6556 currently located at: http://www.iana.org/assignments/gssapi-service- 6557 names 6559 IANA is requested to update the "imap" service name previously 6560 registered in RFC 3501, to point to this document. 6562 13. References 6564 13.1. Normative References 6566 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6567 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6568 . 6570 [ANONYMOUS] 6571 Zeilenga, K., "Anonymous Simple Authentication and 6572 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6573 . 6575 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6576 Procedures", BCP 19, RFC 2978, October 2000, 6577 . 6579 [SCRAM-SHA-256] 6580 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6581 Authentication and Security Layer (SASL) Mechanisms", 6582 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6583 . 6585 [DISPOSITION] 6586 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6587 Presentation Information in Internet Messages: The 6588 Content-Disposition Header Field", RFC 2183, August 1997, 6589 . 6591 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6592 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6593 . 6595 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6596 Requirement Levels", BCP 14, RFC 2119, 6597 DOI 10.17487/RFC2119, March 1997, 6598 . 6600 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6601 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6602 May 2017, . 6604 [LANGUAGE-TAGS] 6605 Alvestrand, H., "Content Language Headers", RFC 3282, May 6606 2002, . 6608 [LOCATION] 6609 Palme, J., Hopmann, A., and N. Shelness, "MIME 6610 Encapsulation of Aggregate Documents, such as HTML 6611 (MHTML)", RFC 2557, March 1999, 6612 . 6614 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6615 RFC 1864, October 1995, 6616 . 6618 [MIME-HDRS] 6619 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6620 Part Three: Message Header Extensions for Non-ASCII Text", 6621 RFC 2047, November 1996, 6622 . 6624 [MIME-IMB] 6625 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6626 Extensions (MIME) Part One: Format of Internet Message 6627 Bodies", RFC 2045, November 1996, 6628 . 6630 [MIME-IMT] 6631 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6632 Extensions (MIME) Part Two: Media Types", RFC 2046, 6633 November 1996, . 6635 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6636 Word Extensions: Character Sets, Languages, and 6637 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6638 1997, . 6640 [RFC-5322] 6641 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6642 October 2008, . 6644 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6645 Authentication and Security Layer (SASL)", RFC 4422, June 6646 2006, . 6648 [TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security 6649 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6650 . 6652 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6653 Transformation Format of Unicode", RFC 2152, May 1997, 6654 . 6656 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6657 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6658 2003, . 6660 [MULTIAPPEND] 6661 Crispin, M., "Internet Message Access Protocol (IMAP) - 6662 MULTIAPPEND Extension", RFC 3502, March 2003, 6663 . 6665 [NET-UNICODE] 6666 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6667 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6668 . 6670 [I18N-HDRS] 6671 Yang, A., Steele, S., and N. Freed, "Internationalized 6672 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6673 2012, . 6675 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6676 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6677 . 6679 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6680 Server Identity Check Procedure for Email-Related 6681 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6682 . 6684 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6685 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6686 February 2017, . 6688 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6689 Use of Transport Layer Security (TLS) for Email Submission 6690 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6691 . 6693 [IMAP-IMPLEMENTATION] 6694 Leiba, B., "IMAP4 Implementation Recommendations", 6695 RFC 2683, September 1999, 6696 . 6698 [IMAP-MULTIACCESS] 6699 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6700 RFC 2180, July 1997, 6701 . 6703 13.2. Informative References (related protocols) 6705 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6706 Protocol - SORT and THREAD Extensions", RFC 5256, 6707 DOI 10.17487/RFC5256, June 2008, 6708 . 6710 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6711 Protocol version 4 - LIST Command Extensions", RFC 5258, 6712 DOI 10.17487/RFC5258, June 2008, 6713 . 6715 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6716 DOI 10.17487/RFC2193, September 1997, 6717 . 6719 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 6720 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 6721 DOI 10.17487/RFC3348, July 2002, 6722 . 6724 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 6725 RFC 7888, DOI 10.17487/RFC7888, May 2016, 6726 . 6728 [IMAP-DISC] 6729 Melnikov, A., Ed., "Synchronization Operations for 6730 Disconnected IMAP4 Clients", RFC 4549, June 2006, 6731 . 6733 [IMAP-I18N] 6734 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 6735 Message Access Protocol Internationalization", RFC 5255, 6736 DOI 10.17487/RFC5255, June 2008, 6737 . 6739 [IMAP-MODEL] 6740 Crispin, M., "Distributed Electronic Mail Models in 6741 IMAP4", RFC 1733, December 1994, 6742 . 6744 [IMAP-UTF-8] 6745 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 6746 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 6747 2013, . 6749 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 6750 October 2008, . 6752 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 6753 DOI 10.17487/RFC3516, April 2003, 6754 . 6756 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 6757 RFC 4314, December 2005, 6758 . 6760 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 6761 1997, . 6763 [IMAP-URL] 6764 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 6765 RFC 5092, DOI 10.17487/RFC5092, November 2007, 6766 . 6768 13.3. Informative References (historical aspects of IMAP and related 6769 protocols) 6771 [IMAP-COMPAT] 6772 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 6773 RFC 2061, December 1996, 6774 . 6776 [IMAP-HISTORICAL] 6777 Crispin, M., "IMAP4 Compatibility with IMAP2 and 6778 IMAP2bis", RFC 1732, December 1994, 6779 . 6781 [IMAP-OBSOLETE] 6782 Crispin, M., "Internet Message Access Protocol - Obsolete 6783 Syntax", RFC 2062, December 1996, 6784 . 6786 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 6787 2", RFC 1176, August 1990, 6788 . 6790 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 6791 TEXT MESSAGES", STD 11, RFC 822, August 1982, 6792 . 6794 [IMAP-TLS] 6795 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 6796 RFC 2595, June 1999, 6797 . 6799 Appendix A. Backward compatibility with IMAP4rev1 6801 An implementation that wants to remain compatible with IMAP4rev1 can 6802 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 6803 response code. While some IMAP4rev1 responses were removed in 6804 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 6806 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 6807 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 6809 Servers advertising both IMAP4rev1 and IMAP4rev2 SHOULD NOT 6811 generate UTF-8 quoted strings unless the client has issued "ENABLE 6812 IMAP4rev2". Consider implementation of mechanisms described or 6813 referenced in [IMAP-UTF-8] to achieve this goal. 6815 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 6816 intending to be compatible with IMAP4rev1 servers MUST be compatible 6817 with the international mailbox naming convention described in the 6818 following subsection. 6820 A.1. Mailbox International Naming Convention for compatibility with 6821 IMAP4rev1 6823 Support for the Mailbox International Naming Convention described in 6824 this section is not required for IMAP4rev2-only clients and servers. 6826 By convention, international mailbox names in IMAP4rev1 are specified 6827 using a modified version of the UTF-7 encoding described in [UTF-7]. 6828 Modified UTF-7 may also be usable in servers that implement an 6829 earlier version of this protocol. 6831 In modified UTF-7, printable US-ASCII characters, except for "&", 6832 represent themselves; that is, characters with octet values 0x20-0x25 6833 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 6834 octet sequence "&-". 6836 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 6837 represented in modified BASE64, with a further modification from 6838 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 6839 used to represent any printing US-ASCII character which can represent 6840 itself. Only characters inside the modified BASE64 alphabet are 6841 permitted in modified BASE64 text. 6843 "&" is used to shift to modified BASE64 and "-" to shift back to US- 6844 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 6845 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 6846 "&") are not permitted. However, all names start in US-ASCII, and 6847 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 6848 ISO-10646 character MUST end with a "-"). 6850 The purpose of these modifications is to correct the following 6851 problems with UTF-7: 6853 1. UTF-7 uses the "+" character for shifting; this conflicts with 6854 the common use of "+" in mailbox names, in particular USENET 6855 newsgroup names. 6857 2. UTF-7's encoding is BASE64 which uses the "/" character; this 6858 conflicts with the use of "/" as a popular hierarchy delimiter. 6860 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 6861 the use of "\" as a popular hierarchy delimiter. 6863 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 6864 the use of "~" in some servers as a home directory indicator. 6866 5. UTF-7 permits multiple alternate forms to represent the same 6867 string; in particular, printable US-ASCII characters can be 6868 represented in encoded form. 6870 Although modified UTF-7 is a convention, it establishes certain 6871 requirements on server handling of any mailbox name with an embedded 6872 "&" character. In particular, server implementations MUST preserve 6873 the exact form of the modified BASE64 portion of a modified UTF-7 6874 name and treat that text as case-sensitive, even if names are 6875 otherwise case-insensitive or case-folded. 6877 Server implementations SHOULD verify that any mailbox name with an 6878 embedded "&" character, used as an argument to CREATE, is: in the 6879 correctly modified UTF-7 syntax, has no superfluous shifts, and has 6880 no encoding in modified BASE64 of any printing US-ASCII character 6881 which can represent itself. However, client implementations MUST NOT 6882 depend upon the server doing this, and SHOULD NOT attempt to create a 6883 mailbox name with an embedded "&" character unless it complies with 6884 the modified UTF-7 syntax. 6886 Server implementations which export a mail store that does not follow 6887 the modified UTF-7 convention MUST convert to modified UTF-7 any 6888 mailbox name that contains either non-ASCII characters or the "&" 6889 character. 6891 For example, here is a mailbox name which mixes English, Chinese, 6892 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 6894 For example, the string "&Jjo!" is not a valid mailbox name 6895 because it does not contain a shift to US-ASCII before the "!". 6896 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 6897 not permitted because it contains a superfluous shift. The 6898 correct form is "&U,BTF2XlZyyKng-". 6900 Appendix B. Backward compatibility with BINARY extension 6902 IMAP4rev2 is incorporates subset of functionality provided by the 6903 BINARY extension [RFC3516], in particular it includes additional 6904 FETCH items (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions 6905 to the APPEND command. IMAP4rev2 implementations that supports full 6906 RFC 3516 functionality need to also advertise the BINARY token in the 6907 CAPABILITY response. 6909 Appendix C. Changes from RFC 3501 / IMAP4rev1 6911 The following is the plan for remaining changes. The plan might 6912 change over time. 6914 1. Fold in the following extensions/RFC: RFC 5530 (IMAP Response 6915 Codes, done), UIDPLUS (done), ENABLE (done), ESEARCH (done), 6916 SPECIAL-USE (list of new mailbox attributes is done), LITERAL- 6917 (done), NAMESPACE (done), SASL-IR (done), IDLE (done), MOVE 6918 (done). 6920 2. Add CLOSED response code (from CONDSTORE) - done 6922 3. Add support for $MDNSent and $Forwarded IMAP keywords - done. 6923 Add more examples showing their use? Also add other keywords 6924 like $Phishing, $Junk, $NonJunk? 6926 4. Require all unsolicited FETCH updates to include UID - done. 6928 5. Update recommendations on TLS ciphers to match UTA WG work (as 6929 per RFC 8314, RFC 7525 and RFC 7817) - done. 6931 6. Possibly fold in the following extensions/RFC: Base LIST- 6932 EXTENDED syntax plus deprecate LSUB (replace it with LIST 6933 \Subscribed) minus the requirement to support multiple list 6934 patterns - done, STATUS-in-LIST - done, SEARCHRES, BINARY (only 6935 the FETCH changes on leaf body part and make APPEND related ones 6936 optional. See the mailing list discussion) - done. 6938 6. 6940 7. Add STATUS SIZE (total mailbox size) - done. Add STATUS DELETED 6941 (number of messages with \Deleted flag set) - done. 6943 8. Drop UTF-7, all mailboxes are always in UTF-8 - done. 6945 9. Revise IANA registration of IMAP extensions and give advice on 6946 use of "X-" convention. 6948 10. Allow word-based searching (as per Chris Newman)? Need to 6949 discuss header field search, where exact/substring match is 6950 still required for interoperability. 6952 The following changes since RFC 3501 were done so far: 6954 1. Folded in IMAP UNSELECT (RFC 3691), UIDPLUS (RFC 4315), ESEARCH 6955 (RFC 4731), ENABLE (RFC 5161), IDLE (RFC 2177), SASL-IR (RFC 6956 4959), LIST-STATUS (RFC 5819) and MOVE (RFC 6851) extensions. 6958 Also folded RFC 5530 and FETCH side of the BINARY extension (RFC 6959 3516). 6961 2. Clarified that server should decode parameter value 6962 continuations as described in [RFC2231]. This requirement was 6963 hidden in RFC 2231 itself. 6965 3. SEARCH command now requires to return ESEARCH response (SEARCH 6966 response is now deprecated). 6968 4. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 6969 mailbox is already selected now require for the CLOSED response 6970 code to be returned. 6972 5. Updated to use modern TLS-related recommendations as per RFC 6973 8314, RFC 7817, RFC 7525. 6975 6. For future extensibility extended ABNF for tagged-ext-simple to 6976 allow for bare number64. 6978 7. Added SHOULD level requirement on IMAP servers to support 6979 $MDNSent and $Forwarded keywords. 6981 8. Added STATUS SIZE and STATUS DELETED. 6983 9. Mailbox names and message headers now allow for UTF-8. Support 6984 for Modified UTF-7 in mailbox names is not required, unless 6985 compatibility with IMAP4rev1 is desired. 6987 10. UNSEEN response code on SELECT/EXAMINE is now deprecated. 6989 11. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 6990 SEARCH NEW items are now deprecated. 6992 12. Clarified that the server doesn't need to send a new 6993 PERMANENTFLAGS response code when a new keyword was successfully 6994 added and the server advertised \* earlier for the same mailbox. 6996 13. Removed the CHECK command. Clients should use NOOP instead. 6998 14. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 6999 deprecated. Clients should use the corresponding BODY[] 7000 variants instead. 7002 15. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7003 MD5 was deprecated. 7005 16. LSUB command was deprecated. Clients should use LIST 7006 (SUBSCRIBED) instead. 7008 17. resp-text ABNF non terminal was updated to allow for empty text. 7010 18. IDLE command can now return updates not related to the currently 7011 selected mailbox state. 7013 Appendix D. Acknowledgement 7015 Earlier versions of this document were edited by Mark Crispin. 7016 Sadly, he is no longer available to help with this work. Editors of 7017 this revisions are hoping that Mark would have approved. 7019 Chris Newman has contributed text on I18N and use of UTF-8 in 7020 messages and mailbox names. 7022 Thank you to Tony Hansen for helping with the index generation. 7023 Thank you to Timo Sirainen, Bron Gondwana and Arnt Gulbrandsen for 7024 extensive feedback. 7026 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7027 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7028 Gulbrandsen), RFC 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo 7029 Sirainen), RFC 6154 (by Jamie Nicolson) 7031 so work done by authors/editors of these documents is appreciated. 7032 Note that editors of this document were redacted from the above list. 7034 Index 7036 $ 7037 $Forwarded (predefined flag) 12 7038 $MDNSent (predefined flag) 12 7040 + 7041 +FLAGS 90 7042 +FLAGS.SILENT 90 7044 - 7045 -FLAGS 90 7046 -FLAGS.SILENT 90 7048 A 7049 ALERT (response code) 97 7050 ALL (fetch item) 86 7051 ALL (search key) 76 7052 ALL (search result option) 74 7053 ALREADYEXISTS (response code) 97 7054 ANSWERED (search key) 76 7055 APPEND (command) 66 7056 APPENDUID (response code) 97 7057 AUTHENTICATE (command) 28 7058 AUTHENTICATIONFAILED (response code) 98 7059 AUTHORIZATIONFAILED (response code) 98 7061 B 7062 BAD (response) 106 7063 BADCHARSET (response code) 99 7064 BCC (search key) 76 7065 BEFORE (search key) 76 7066 BINARY.PEEK[]<> (fetch item) 86 7067 BINARY.SIZE[] (fetch item) 86 7068 BINARY.SIZE[] (fetch result) 116 7069 BINARY[]<> (fetch result) 115 7070 BINARY[]<> (fetch item) 86 7071 BODY (fetch item) 87 7072 BODY (fetch result) 116 7073 BODY (search key) 76 7074 BODY.PEEK[
]<> (fetch item) 89 7075 BODYSTRUCTURE (fetch item) 89 7076 BODYSTRUCTURE (fetch result) 117 7077 BODY[
]<> (fetch result) 116 7078 BODY[
]<> (fetch item) 87 7079 BYE (response) 106 7080 Body Structure (message attribute) 13 7082 C 7083 CANNOT (response code) 99 7084 CAPABILITY (command) 24 7085 CAPABILITY (response code) 99 7086 CAPABILITY (response) 107 7087 CC (search key) 76 7088 CLIENTBUG (response code) 99 7089 CLOSE (command) 71 7090 CLOSED (response code) 99 7091 CONTACTADMIN (response code) 100 7092 COPY (command) 90 7093 COPYUID (response code) 100 7094 CORRUPTION (response code) 100 7095 COUNT (search result option) 74 7096 CREATE (command) 37 7098 D 7099 DELETE (command) 38 7100 DELETED (search key) 76 7101 DELETED (status item) 66 7102 DRAFT (search key) 76 7104 E 7105 ENABLE (command) 32 7106 ENVELOPE (fetch item) 89 7107 ENVELOPE (fetch result) 119 7108 ESEARCH (response) 113 7109 EXAMINE (command) 36 7110 EXPIRED (response code) 101 7111 EXPUNGE (command) 72 7112 EXPUNGE (response) 114 7113 EXPUNGEISSUED (response code) 101 7114 Envelope Structure (message attribute) 13 7116 F 7117 FAST (fetch item) 86 7118 FETCH (command) 85 7119 FETCH (response) 115 7120 FLAGGED (search key) 76 7121 FLAGS (fetch item) 89 7122 FLAGS (fetch result) 120 7123 FLAGS (response) 113 7124 FLAGS (store command data item) 90 7125 FLAGS.SILENT (store command data item) 90 7126 FROM (search key) 76 7127 FULL (fetch item) 86 7128 Flags (message attribute) 11 7130 H 7131 HEADER (part specifier) 87 7132 HEADER (search key) 76 7133 HEADER.FIELDS (part specifier) 87 7134 HEADER.FIELDS.NOT (part specifier) 87 7136 I 7137 IDLE (command) 69 7138 INTERNALDATE (fetch item) 89 7139 INTERNALDATE (fetch result) 120 7140 INUSE (response code) 101 7141 Internal Date (message attribute) 12 7143 K 7144 KEYWORD (search key) 77 7145 Keyword (type of flag) 12 7147 L 7148 LARGER (search key) 77 7149 LIMIT (response code) 101 7150 LIST (command) 42 7151 LIST (response) 108 7152 LOGOUT (command) 26 7154 M 7155 MAX (search result option) 74 7156 MAY (specification requirement term) 5 7157 MESSAGES (status item) 66 7158 MIME (part specifier) 88 7159 MIN (search result option) 74 7160 MOVE (command) 91 7161 MUST (specification requirement term) 5 7162 MUST NOT (specification requirement term) 5 7163 Message Sequence Number (message attribute) 11 7165 N 7166 NAMESPACE (command) 60 7167 NAMESPACE (response) 112 7168 NO (response) 105 7169 NONEXISTENT (response code) 102 7170 NOOP (command) 25 7171 NOPERM (response code) 102 7172 NOT (search key) 77 7173 NOT RECOMMENDED (specification requirement term) 5 7175 O 7176 OK (response) 105 7177 ON (search key) 77 7178 OPTIONAL (specification requirement term) 5 7179 OR (search key) 77 7180 OVERQUOTA (response code) 102 7182 P 7183 PARSE (response code) 102 7184 PERMANENTFLAGS (response code) 102 7185 PREAUTH (response) 106 7186 PRIVACYREQUIRED (response code) 103 7187 Permanent Flag (class of flag) 12 7188 Predefined keywords 12 7190 R 7191 READ-ONLY (response code) 103 7192 READ-WRITE (response code) 103 7193 RECOMMENDED (specification requirement term) 5 7194 RENAME (command) 39 7195 REQUIRED (specification requirement term) 5 7196 RFC822.SIZE (fetch item) 89 7197 RFC822.SIZE (fetch result) 121 7199 S 7200 SAVE (search result option) 74 7201 SEARCH (command) 73 7202 SEEN (search key) 77 7203 SELECT (command) 34 7204 SENTBEFORE (search key) 77 7205 SENTON (search key) 77 7206 SENTSINCE (search key) 77 7207 SERVERBUG (response code) 103 7208 SHOULD (specification requirement term) 5 7209 SHOULD NOT (specification requirement term) 5 7210 SINCE (search key) 77 7211 SIZE (status item) 66 7212 SMALLER (search key) 77 7213 STARTTLS (command) 27 7214 STATUS (command) 65 7215 STATUS (response) 112 7216 STORE (command) 89 7217 SUBJECT (search key) 77 7218 SUBSCRIBE (command) 41 7219 Session Flag (class of flag) 12 7220 System Flag (type of flag) 11 7222 T 7223 TEXT (part specifier) 87 7224 TEXT (search key) 77 7225 TO (search key) 77 7226 TRYCREATE (response code) 103 7228 U 7229 UID (command) 93 7230 UID (fetch item) 89 7231 UID (fetch result) 121 7232 UID (search key) 78 7233 UIDNEXT (response code) 104 7234 UIDNEXT (status item) 66 7235 UIDNOTSTICKY (response code) 104 7236 UIDVALIDITY (response code) 104 7237 UIDVALIDITY (status item) 66 7238 UNANSWERED (search key) 78 7239 UNAVAILABLE (response code) 104 7240 UNDELETED (search key) 78 7241 UNDRAFT (search key) 78 7242 UNFLAGGED (search key) 78 7243 UNKEYWORD (search key) 78 7244 UNKNOWN-CTE (response code) 104 7245 UNSEEN (search key) 78 7246 UNSEEN (status item) 66 7247 UNSELECT (command) 72 7248 UNSUBSCRIBE (command) 42 7249 Unique Identifier (UID) (message attribute) 9 7251 X 7252 X (command) 95 7254 [ 7255 [RFC-5322] Size (message attribute) 13 7257 \ 7258 \All (mailbox name attribute) 110 7259 \Answered (system flag) 11 7260 \Archive (mailbox name attribute) 110 7261 \Deleted (system flag) 12 7262 \Draft (system flag) 12 7263 \Drafts (mailbox name attribute) 110 7264 \Flagged (mailbox name attribute) 111 7265 \Flagged (system flag) 11 7266 \HasChildren (mailbox name attribute) 109 7267 \HasNoChildren (mailbox name attribute) 109 7268 \Junk (mailbox name attribute) 111 7269 \Marked (mailbox name attribute) 110 7270 \Noinferiors (mailbox name attribute) 109 7271 \NonExistent (mailbox name attribute) 109 7272 \Noselect (mailbox name attribute) 109 7273 \Recent (system flag) 12 7274 \Remote (mailbox name attribute) 110 7275 \Seen (system flag) 11 7276 \Sent (mailbox name attribute) 111 7277 \Subscribed (mailbox name attribute) 110 7278 \Trash (mailbox name attribute) 111 7279 \Unmarked (mailbox name attribute) 110 7281 Authors' Addresses 7283 Alexey Melnikov (editor) 7284 Isode Ltd 7285 14 Castle Mews 7286 Hampton, Middlesex TW12 2NP 7287 UK 7289 Email: Alexey.Melnikov@isode.com 7290 Barry Leiba (editor) 7291 Huawei Technologies 7293 Phone: +1 646 827 0648 7294 Email: barryleiba@computer.org 7295 URI: http://internetmessagingtechnology.org/