idnits 2.17.00 (12 Aug 2021) /tmp/idnits36661/draft-ietf-extra-imap4rev2-18.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 3 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 (September 15, 2020) is 612 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'IMAP2' is mentioned on line 7049, but not defined == Missing Reference: 'IMAP-OBSOLETE' is mentioned on line 7044, but not defined == Missing Reference: 'IMAP-COMPAT' is mentioned on line 7034, but not defined == Missing Reference: 'IMAP-HISTORICAL' is mentioned on line 7039, but not defined == Missing Reference: 'RFC-822' is mentioned on line 7053, but not defined ** Obsolete undefined reference: RFC 822 (Obsoleted by RFC 2822) == Missing Reference: 'IMAP-MODEL' is mentioned on line 6983, but not defined == Missing Reference: 'IMAP-DISC' is mentioned on line 6972, but not defined == Missing Reference: 'RFC3503' is mentioned on line 6945, but not defined == Missing Reference: 'IMAP-KEYWORDS-REG' is mentioned on line 7012, but not defined == Missing Reference: 'SMTP' is mentioned on line 6993, but not defined == Missing Reference: 'RFC7888' is mentioned on line 6968, but not defined -- Looks like a reference, but probably isn't: '1' on line 886 == Missing Reference: 'IMAP-URL' is mentioned on line 7007, but not defined == Missing Reference: 'UIDVALIDITY 3857529045' is mentioned on line 5763, but not defined == Missing Reference: 'UIDNEXT 4392' is mentioned on line 1728, but not defined == Missing Reference: 'RFC2193' is mentioned on line 6955, but not defined == Missing Reference: 'RFC3348' is mentioned on line 7314, but not defined ** Obsolete undefined reference: RFC 3348 (Obsoleted by RFC 5258) == Missing Reference: 'RFC4314' is mentioned on line 7000, but not defined == Missing Reference: 'RFC3501' is mentioned on line 7030, but not defined ** Obsolete undefined reference: RFC 3501 (Obsoleted by RFC 9051) == Missing Reference: 'UIDNEXT 2' is mentioned on line 3258, but not defined == Missing Reference: 'UIDVALIDITY 1' is mentioned on line 3330, but not defined == Missing Reference: 'CHARSET-REG' is mentioned on line 7022, but not defined == Missing Reference: 'IMAP-I18N' is mentioned on line 6977, but not defined == Missing Reference: 'HEADER' is mentioned on line 5781, but not defined == Missing Reference: 'BADCHARSET UTF-8' is mentioned on line 3910, but not defined == Missing Reference: 'UID' is mentioned on line 4338, but not defined == Missing Reference: 'RFC2087' is mentioned on line 7004, but not defined ** Obsolete undefined reference: RFC 2087 (Obsoleted by RFC 9208) == Missing Reference: 'IMAP-MAILBOX-NAME-ATTRS-REG' is mentioned on line 7017, but not defined == Missing Reference: 'READ-WRITE' is mentioned on line 5765, but not defined == Missing Reference: 'RFC4422' is mentioned on line 6112, but not defined == Missing Reference: 'IMAP4' is mentioned on line 6197, but not defined == Missing Reference: 'Namespace-Response-Extensions' is mentioned on line 6267, but not defined == Missing Reference: 'IMAP-TLS' is mentioned on line 7057, but not defined == Missing Reference: 'RFCXXXX' is mentioned on line 6789, but not defined == Missing Reference: 'RFC5465' is mentioned on line 6964, but not defined == Missing Reference: 'RFC5256' is mentioned on line 6950, but not defined == Missing Reference: 'IMAP-UTF-8' is mentioned on line 7075, but not defined == Missing Reference: 'RFC3516' is mentioned on line 7165, but not defined ** Obsolete normative reference: RFC 5246 (ref. 'TLS') (Obsoleted by RFC 8446) ** Downref: Normative reference to an Informational RFC: RFC 2152 (ref. 'UTF-7') ** Downref: Normative reference to an Informational RFC: RFC 2683 (ref. 'IMAP-IMPLEMENTATION') ** Downref: Normative reference to an Informational RFC: RFC 2180 (ref. 'IMAP-MULTIACCESS') Summary: 10 errors (**), 0 flaws (~~), 39 warnings (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Melnikov, Ed. 3 Internet-Draft Isode Ltd 4 Obsoletes: 3501 (if approved) B. Leiba, Ed. 5 Intended status: Standards Track Futurewei Technologies 6 Expires: March 19, 2021 September 15, 2020 8 Internet Message Access Protocol (IMAP) - Version 4rev2 9 draft-ietf-extra-imap4rev2-18 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 March 19, 2021. 48 Copyright Notice 50 Copyright (c) 2020 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (https://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 This document may contain material from IETF Documents or IETF 64 Contributions published or made publicly available before November 65 10, 2008. The person(s) controlling the copyright in some of this 66 material may not have granted the IETF Trust the right to allow 67 modifications of such material outside the IETF Standards Process. 68 Without obtaining an adequate license from the person(s) controlling 69 the copyright in such materials, this document may not be modified 70 outside the IETF Standards Process, and derivative works of it may 71 not be created outside the IETF Standards Process, except to format 72 it for publication as an RFC or to translate it into languages other 73 than English. 75 Table of Contents 77 1. How to Read This Document . . . . . . . . . . . . . . . . . . 5 78 1.1. Organization of This Document . . . . . . . . . . . . . . 5 79 1.2. Conventions Used in This Document . . . . . . . . . . . . 5 80 1.3. Special Notes to Implementors . . . . . . . . . . . . . . 6 81 2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 82 2.1. Link Level . . . . . . . . . . . . . . . . . . . . . . . 7 83 2.2. Commands and Responses . . . . . . . . . . . . . . . . . 7 84 2.2.1. Client Protocol Sender and Server Protocol Receiver . 7 85 2.2.2. Server Protocol Sender and Client Protocol Receiver . 8 86 2.3. Message Attributes . . . . . . . . . . . . . . . . . . . 9 87 2.3.1. Message Numbers . . . . . . . . . . . . . . . . . . . 9 88 2.3.2. Flags Message Attribute . . . . . . . . . . . . . . . 11 89 2.3.3. Internal Date Message Attribute . . . . . . . . . . . 13 90 2.3.4. [RFC-5322] Size Message Attribute . . . . . . . . . . 14 91 2.3.5. Envelope Structure Message Attribute . . . . . . . . 14 92 2.3.6. Body Structure Message Attribute . . . . . . . . . . 14 93 2.4. Message Texts . . . . . . . . . . . . . . . . . . . . . . 14 94 3. State and Flow Diagram . . . . . . . . . . . . . . . . . . . 14 95 3.1. Not Authenticated State . . . . . . . . . . . . . . . . . 14 96 3.2. Authenticated State . . . . . . . . . . . . . . . . . . . 14 97 3.3. Selected State . . . . . . . . . . . . . . . . . . . . . 15 98 3.4. Logout State . . . . . . . . . . . . . . . . . . . . . . 15 99 4. Data Formats . . . . . . . . . . . . . . . . . . . . . . . . 17 100 4.1. Atom . . . . . . . . . . . . . . . . . . . . . . . . . . 17 101 4.1.1. Sequence set and UID set . . . . . . . . . . . . . . 17 102 4.2. Number . . . . . . . . . . . . . . . . . . . . . . . . . 17 103 4.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 17 104 4.3.1. 8-bit and Binary Strings . . . . . . . . . . . . . . 18 105 4.4. Parenthesized List . . . . . . . . . . . . . . . . . . . 19 106 4.5. NIL . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 107 5. Operational Considerations . . . . . . . . . . . . . . . . . 20 108 5.1. Mailbox Naming . . . . . . . . . . . . . . . . . . . . . 20 109 5.1.1. Mailbox Hierarchy Naming . . . . . . . . . . . . . . 21 110 5.1.2. Namespaces . . . . . . . . . . . . . . . . . . . . . 21 111 5.2. Mailbox Size and Message Status Updates . . . . . . . . . 23 112 5.3. Response when no Command in Progress . . . . . . . . . . 23 113 5.4. Autologout Timer . . . . . . . . . . . . . . . . . . . . 23 114 5.5. Multiple Commands in Progress (Command Pipelining) . . . 23 115 6. Client Commands . . . . . . . . . . . . . . . . . . . . . . . 25 116 6.1. Client Commands - Any State . . . . . . . . . . . . . . . 25 117 6.1.1. CAPABILITY Command . . . . . . . . . . . . . . . . . 25 118 6.1.2. NOOP Command . . . . . . . . . . . . . . . . . . . . 26 119 6.1.3. LOGOUT Command . . . . . . . . . . . . . . . . . . . 27 120 6.2. Client Commands - Not Authenticated State . . . . . . . . 27 121 6.2.1. STARTTLS Command . . . . . . . . . . . . . . . . . . 28 122 6.2.2. AUTHENTICATE Command . . . . . . . . . . . . . . . . 29 123 6.2.3. LOGIN Command . . . . . . . . . . . . . . . . . . . . 32 124 6.3. Client Commands - Authenticated State . . . . . . . . . . 33 125 6.3.1. ENABLE Command . . . . . . . . . . . . . . . . . . . 33 126 6.3.2. SELECT Command . . . . . . . . . . . . . . . . . . . 35 127 6.3.3. EXAMINE Command . . . . . . . . . . . . . . . . . . . 37 128 6.3.4. CREATE Command . . . . . . . . . . . . . . . . . . . 38 129 6.3.5. DELETE Command . . . . . . . . . . . . . . . . . . . 39 130 6.3.6. RENAME Command . . . . . . . . . . . . . . . . . . . 41 131 6.3.7. SUBSCRIBE Command . . . . . . . . . . . . . . . . . . 43 132 6.3.8. UNSUBSCRIBE Command . . . . . . . . . . . . . . . . . 44 133 6.3.9. LIST Command . . . . . . . . . . . . . . . . . . . . 44 134 6.3.10. NAMESPACE Command . . . . . . . . . . . . . . . . . . 62 135 6.3.11. STATUS Command . . . . . . . . . . . . . . . . . . . 67 136 6.3.12. APPEND Command . . . . . . . . . . . . . . . . . . . 68 137 6.3.13. IDLE Command . . . . . . . . . . . . . . . . . . . . 71 138 6.4. Client Commands - Selected State . . . . . . . . . . . . 73 139 6.4.1. CLOSE Command . . . . . . . . . . . . . . . . . . . . 74 140 6.4.2. UNSELECT Command . . . . . . . . . . . . . . . . . . 74 141 6.4.3. EXPUNGE Command . . . . . . . . . . . . . . . . . . . 75 142 6.4.4. SEARCH Command . . . . . . . . . . . . . . . . . . . 75 143 6.4.5. FETCH Command . . . . . . . . . . . . . . . . . . . . 87 144 6.4.6. STORE Command . . . . . . . . . . . . . . . . . . . . 92 145 6.4.7. COPY Command . . . . . . . . . . . . . . . . . . . . 93 146 6.4.8. MOVE Command . . . . . . . . . . . . . . . . . . . . 94 147 6.4.9. UID Command . . . . . . . . . . . . . . . . . . . . . 96 148 6.5. Client Commands - Experimental/Expansion . . . . . . . . 97 149 6.5.1. X Command . . . . . . . . . . . . . . . . . . . 97 150 7. Server Responses . . . . . . . . . . . . . . . . . . . . . . 98 151 7.1. Server Responses - Status Responses . . . . . . . . . . . 99 152 7.1.1. OK Response . . . . . . . . . . . . . . . . . . . . . 107 153 7.1.2. NO Response . . . . . . . . . . . . . . . . . . . . . 108 154 7.1.3. BAD Response . . . . . . . . . . . . . . . . . . . . 108 155 7.1.4. PREAUTH Response . . . . . . . . . . . . . . . . . . 108 156 7.1.5. BYE Response . . . . . . . . . . . . . . . . . . . . 109 157 7.2. Server Responses - Server and Mailbox Status . . . . . . 109 158 7.2.1. The ENABLED Response . . . . . . . . . . . . . . . . 110 159 7.2.2. CAPABILITY Response . . . . . . . . . . . . . . . . . 110 160 7.2.3. LIST Response . . . . . . . . . . . . . . . . . . . . 111 161 7.2.4. NAMESPACE Response . . . . . . . . . . . . . . . . . 115 162 7.2.5. STATUS Response . . . . . . . . . . . . . . . . . . . 115 163 7.2.6. ESEARCH Response . . . . . . . . . . . . . . . . . . 115 164 7.2.7. FLAGS Response . . . . . . . . . . . . . . . . . . . 116 165 7.3. Server Responses - Mailbox Size . . . . . . . . . . . . . 116 166 7.3.1. EXISTS Response . . . . . . . . . . . . . . . . . . . 116 167 7.4. Server Responses - Message Status . . . . . . . . . . . . 117 168 7.4.1. EXPUNGE Response . . . . . . . . . . . . . . . . . . 117 169 7.4.2. FETCH Response . . . . . . . . . . . . . . . . . . . 118 170 7.5. Server Responses - Command Continuation Request . . . . . 124 171 8. Sample IMAP4rev2 connection . . . . . . . . . . . . . . . . . 124 172 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . . 125 173 10. Author's Note . . . . . . . . . . . . . . . . . . . . . . . . 143 174 11. Security Considerations . . . . . . . . . . . . . . . . . . . 143 175 11.1. STARTTLS Security Considerations . . . . . . . . . . . . 143 176 11.2. COPYUID and APPENDUID response codes . . . . . . . . . . 144 177 11.3. LIST command and Other Users' namespace . . . . . . . . 144 178 11.4. Other Security Considerations . . . . . . . . . . . . . 144 179 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 145 180 12.1. Updates to IMAP4 Capabilities registry . . . . . . . . . 145 181 12.2. GSSAPI/SASL service name . . . . . . . . . . . . . . . . 146 182 12.3. LIST Selection Options, LIST Return Options, LIST 183 extended data items . . . . . . . . . . . . . . . . . . 146 184 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 146 185 13.1. Normative References . . . . . . . . . . . . . . . . . . 146 186 13.2. Informative References (related protocols) . . . . . . . 149 187 13.3. Informative References (historical aspects of IMAP and 188 related protocols) . . . . . . . . . . . . . . . . . . . 151 189 Appendix A. Backward compatibility with IMAP4rev1 . . . . . . . 152 190 A.1. Mailbox International Naming Convention for compatibility 191 with IMAP4rev1 . . . . . . . . . . . . . . . . . . . . . 152 193 Appendix B. Backward compatibility with BINARY extension . . . . 154 194 Appendix C. Backward compatibility with LIST-EXTENDED extension 154 195 Appendix D. Changes from RFC 3501 / IMAP4rev1 . . . . . . . . . 154 196 Appendix E. Acknowledgement . . . . . . . . . . . . . . . . . . 157 197 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 198 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 162 200 1. How to Read This Document 202 1.1. Organization of This Document 204 This document is written from the point of view of the implementor of 205 an IMAP4rev2 client or server. Beyond the protocol overview in 206 section 2, it is not optimized for someone trying to understand the 207 operation of the protocol. The material in sections 3 through 5 208 provides the general context and definitions with which IMAP4rev2 209 operates. 211 Sections 6, 7, and 9 describe the IMAP commands, responses, and 212 syntax, respectively. The relationships among these are such that it 213 is almost impossible to understand any of them separately. In 214 particular, do not attempt to deduce command syntax from the command 215 section alone; instead refer to the Formal Syntax section. 217 1.2. Conventions Used in This Document 219 "Conventions" are basic principles or procedures. Document 220 conventions are noted in this section. 222 In examples, "C:" and "S:" indicate lines sent by the client and 223 server respectively. 225 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 226 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 227 "OPTIONAL" in this document are to be interpreted as described in BCP 228 14 [RFC2119] [RFC8174] when, and only when, they appear in all 229 capitals, as shown here. 231 The word "can" (not "may") is used to refer to a possible 232 circumstance or situation, as opposed to an optional facility of the 233 protocol. 235 "User" is used to refer to a human user, whereas "client" refers to 236 the software being run by the user. 238 "Connection" refers to the entire sequence of client/server 239 interaction from the initial establishment of the network connection 240 until its termination. 242 "Session" refers to the sequence of client/server interaction from 243 the time that a mailbox is selected (SELECT or EXAMINE command) until 244 the time that selection ends (SELECT or EXAMINE of another mailbox, 245 CLOSE command, UNSELECT command, or connection termination). 247 Characters are 8-bit UTF-8 (of which 7-bit US-ASCII is a subset) 248 unless otherwise specified. Other character sets are indicated using 249 a "CHARSET", as described in [MIME-IMT] and defined in [CHARSET]. 250 CHARSETs have important additional semantics in addition to defining 251 character set; refer to these documents for more detail. 253 There are several protocol conventions in IMAP. These refer to 254 aspects of the specification which are not strictly part of the IMAP 255 protocol, but reflect generally-accepted practice. Implementations 256 need to be aware of these conventions, and avoid conflicts whether or 257 not they implement the convention. For example, "&" may not be used 258 as a hierarchy delimiter since it conflicts with the Mailbox 259 International Naming Convention, and other uses of "&" in mailbox 260 names are impacted as well. 262 1.3. Special Notes to Implementors 264 Implementors of the IMAP protocol are strongly encouraged to read the 265 IMAP implementation recommendations document [IMAP-IMPLEMENTATION] in 266 conjunction with this document, to help understand the intricacies of 267 this protocol and how best to build an interoperable product. 269 IMAP4rev2 is designed to be upwards compatible from the [IMAP2] and 270 unpublished IMAP2bis protocols. IMAP4rev2 is largely compatible with 271 the IMAP4rev1 protocol described in RFC 3501 and the IMAP4 protocol 272 described in RFC 1730; the exception being in certain facilities 273 added in RFC 1730 that proved problematic and were subsequently 274 removed. In the course of the evolution of IMAP4rev2, some aspects 275 in the earlier protocols have become obsolete. Obsolete commands, 276 responses, and data formats which an IMAP4rev2 implementation can 277 encounter when used with an earlier implementation are described in 278 Appendix D and [IMAP-OBSOLETE]. 280 Other compatibility issues with IMAP2bis, the most common variant of 281 the earlier protocol, are discussed in [IMAP-COMPAT]. A full 282 discussion of compatibility issues with rare (and presumed extinct) 283 variants of [IMAP2] is in [IMAP-HISTORICAL]; this document is 284 primarily of historical interest. 286 IMAP was originally developed for the older [RFC-822] standard, and 287 as a consequence several fetch items in IMAP incorporate "RFC822" in 288 their name. In all cases, "RFC822" should be interpreted as a 289 reference to the updated [RFC-5322] standard. 291 2. Protocol Overview 293 2.1. Link Level 295 The IMAP4rev2 protocol assumes a reliable data stream such as that 296 provided by TCP. When TCP is used, an IMAP4rev2 server listens on 297 port 143 or port 993 (IMAP-over-TLS). 299 2.2. Commands and Responses 301 An IMAP4rev2 connection consists of the establishment of a client/ 302 server network connection, an initial greeting from the server, and 303 client/server interactions. These client/server interactions consist 304 of a client command, server data, and a server completion result 305 response. 307 All interactions transmitted by client and server are in the form of 308 lines, that is, strings that end with a CRLF. The protocol receiver 309 of an IMAP4rev2 client or server is either reading a line, or is 310 reading a sequence of octets with a known count followed by a line. 312 2.2.1. Client Protocol Sender and Server Protocol Receiver 314 The client command begins an operation. Each client command is 315 prefixed with an identifier (typically a short alphanumeric string, 316 e.g., A0001, A0002, etc.) called a "tag". A different tag is 317 generated by the client for each command. (More formally: the client 318 SHOULD generate a unique tag for every command, but a server MUST 319 accept tag reuse.) 321 Clients MUST follow the syntax outlined in this specification 322 strictly. It is a syntax error to send a command with missing or 323 extraneous spaces or arguments. 325 There are two cases in which a line from the client does not 326 represent a complete command. In one case, a command argument is 327 quoted with an octet count (see the description of literal in String 328 under Data Formats); in the other case, the command arguments require 329 server feedback (see the AUTHENTICATE command). In either case, the 330 server sends a command continuation request response if it is ready 331 for the octets (if appropriate) and the remainder of the command. 332 This response is prefixed with the token "+". 334 Note: If instead, the server detected an error in the command, it 335 sends a BAD completion response with a tag matching the command 336 (as described below) to reject the command and prevent the client 337 from sending any more of the command. 339 It is also possible for the server to send a completion response 340 for some other command (if multiple commands are in progress), or 341 untagged data. In either case, the command continuation request 342 is still pending; the client takes the appropriate action for the 343 response, and reads another response from the server. In all 344 cases, the client MUST send a complete command (including 345 receiving all command continuation request responses and command 346 continuations for the command) before initiating a new command. 348 The protocol receiver of an IMAP4rev2 server reads a command line 349 from the client, parses the command and its arguments, and transmits 350 server data and a server command completion result response. 352 2.2.2. Server Protocol Sender and Client Protocol Receiver 354 Data transmitted by the server to the client and status responses 355 that do not indicate command completion are prefixed with the token 356 "*", and are called untagged responses. 358 Server data MAY be sent as a result of a client command, or MAY be 359 sent unilaterally by the server. There is no syntactic difference 360 between server data that resulted from a specific command and server 361 data that were sent unilaterally. 363 The server completion result response indicates the success or 364 failure of the operation. It is tagged with the same tag as the 365 client command which began the operation. Thus, if more than one 366 command is in progress, the tag in a server completion response 367 identifies the command to which the response applies. There are 368 three possible server completion responses: OK (indicating success), 369 NO (indicating failure), or BAD (indicating a protocol error such as 370 unrecognized command or command syntax error). 372 Servers SHOULD enforce the syntax outlined in this specification 373 strictly. Any client command with a protocol syntax error, including 374 (but not limited to) missing or extraneous spaces or arguments, 375 SHOULD be rejected, and the client given a BAD server completion 376 response. 378 The protocol receiver of an IMAP4rev2 client reads a response line 379 from the server. It then takes action on the response based upon the 380 first token of the response, which can be a tag, a "*", or a "+". 382 A client MUST be prepared to accept any server response at all times. 383 This includes server data that was not requested. Server data SHOULD 384 be recorded, so that the client can reference its recorded copy 385 rather than sending a command to the server to request the data. In 386 the case of certain server data, the data MUST be recorded. 388 This topic is discussed in greater detail in the Server Responses 389 section. 391 2.3. Message Attributes 393 In addition to message text, each message has several attributes 394 associated with it. These attributes can be retrieved individually 395 or in conjunction with other attributes or message texts. 397 2.3.1. Message Numbers 399 Messages in IMAP4rev2 are accessed by one of two numbers; the unique 400 identifier or the message sequence number. 402 2.3.1.1. Unique Identifier (UID) Message Attribute 404 An unsigned non-zero 32-bit value assigned to each message, which 405 when used with the unique identifier validity value (see below) forms 406 a 64-bit value that MUST NOT refer to any other message in the 407 mailbox or any subsequent mailbox with the same name forever. Unique 408 identifiers are assigned in a strictly ascending fashion in the 409 mailbox; as each message is added to the mailbox it is assigned a 410 higher UID than the message(s) which were added previously. Unlike 411 message sequence numbers, unique identifiers are not necessarily 412 contiguous. 414 The unique identifier of a message MUST NOT change during the 415 session, and SHOULD NOT change between sessions. Any change of 416 unique identifiers between sessions MUST be detectable using the 417 UIDVALIDITY mechanism discussed below. Persistent unique identifiers 418 are required for a client to resynchronize its state from a previous 419 session with the server (e.g., disconnected or offline access clients 420 [IMAP-MODEL]); this is discussed further in [IMAP-DISC]. 422 Associated with every mailbox are two 32-bit unsigned non-zero values 423 which aid in unique identifier handling: the next unique identifier 424 value (UIDNEXT) and the unique identifier validity value 425 (UIDVALIDITY). 427 The next unique identifier value is the predicted value that will be 428 assigned to a new message in the mailbox. Unless the unique 429 identifier validity also changes (see below), the next unique 430 identifier value MUST have the following two characteristics. First, 431 the next unique identifier value MUST NOT change unless new messages 432 are added to the mailbox; and second, the next unique identifier 433 value MUST change whenever new messages are added to the mailbox, 434 even if those new messages are subsequently expunged. 436 Note: The next unique identifier value is intended to provide a 437 means for a client to determine whether any messages have been 438 delivered to the mailbox since the previous time it checked this 439 value. It is not intended to provide any guarantee that any 440 message will have this unique identifier. A client can only 441 assume, at the time that it obtains the next unique identifier 442 value, that messages arriving after that time will have a UID 443 greater than or equal to that value. 445 The unique identifier validity value is sent in a UIDVALIDITY 446 response code in an OK untagged response at mailbox selection time. 447 If unique identifiers from an earlier session fail to persist in this 448 session, the unique identifier validity value MUST be greater than 449 the one used in the earlier session. A good UIDVALIDITY value to use 450 is a 32-bit representation of the current date/time when the value is 451 assigned: this ensures that the value is unique and always increases. 452 Another possible alternative is a global counter that gets 453 incremented every time a mailbox is created. 455 Note: Ideally, unique identifiers SHOULD persist at all times. 456 Although this specification recognizes that failure to persist can 457 be unavoidable in certain server environments, it STRONGLY 458 ENCOURAGES message store implementation techniques that avoid this 459 problem. For example: 461 1. Unique identifiers MUST be strictly ascending in the mailbox 462 at all times. If the physical message store is re-ordered by 463 a non-IMAP agent, this requires that the unique identifiers in 464 the mailbox be regenerated, since the former unique 465 identifiers are no longer strictly ascending as a result of 466 the re-ordering. 468 2. If the message store has no mechanism to store unique 469 identifiers, it must regenerate unique identifiers at each 470 session, and each session must have a unique UIDVALIDITY 471 value. 473 3. If the mailbox is deleted/renamed and a new mailbox with the 474 same name is created at a later date, the server must either 475 keep track of unique identifiers from the previous instance of 476 the mailbox, or it must assign a new UIDVALIDITY value to the 477 new instance of the mailbox. 479 4. The combination of mailbox name, UIDVALIDITY, and UID must 480 refer to a single immutable (or expunged) message on that 481 server forever. In particular, the internal date, [RFC-5322] 482 size, envelope, body structure, and message texts (all 483 BODY[...] fetch data items) must never change. This does not 484 include message numbers, nor does it include attributes that 485 can be set by a STORE command (e.g., FLAGS). When a message 486 is expunged, its UID MUST NOT be reused under the same 487 UIDVALIDITY value. 489 2.3.1.2. Message Sequence Number Message Attribute 491 A relative position from 1 to the number of messages in the mailbox. 492 This position MUST be ordered by ascending unique identifier. As 493 each new message is added, it is assigned a message sequence number 494 that is 1 higher than the number of messages in the mailbox before 495 that new message was added. 497 Message sequence numbers can be reassigned during the session. For 498 example, when a message is permanently removed (expunged) from the 499 mailbox, the message sequence number for all subsequent messages is 500 decremented. The number of messages in the mailbox is also 501 decremented. Similarly, a new message can be assigned a message 502 sequence number that was once held by some other message prior to an 503 expunge. 505 In addition to accessing messages by relative position in the 506 mailbox, message sequence numbers can be used in mathematical 507 calculations. For example, if an untagged "11 EXISTS" is received, 508 and previously an untagged "8 EXISTS" was received, three new 509 messages have arrived with message sequence numbers of 9, 10, and 11. 510 Another example, if message 287 in a 523 message mailbox has UID 511 12345, there are exactly 286 messages which have lesser UIDs and 236 512 messages which have greater UIDs. 514 2.3.2. Flags Message Attribute 516 A list of zero or more named tokens associated with the message. A 517 flag is set by its addition to this list, and is cleared by its 518 removal. There are two types of flags in IMAP4rev2. A flag of 519 either type can be permanent or session-only. 521 A system flag is a flag name that is pre-defined in this 522 specification and begin with "\". Certain system flags (\Deleted and 523 \Seen) have special semantics described elsewhere in this document. 524 The currently-defined system flags are: 526 \Seen Message has been read 528 \Answered Message has been answered 530 \Flagged Message is "flagged" for urgent/special attention 531 \Deleted Message is "deleted" for removal by later EXPUNGE 533 \Draft Message has not completed composition (marked as a draft). 535 \Recent This flag was in used in IMAP4rev1 and is now deprecated. 537 A keyword is defined by the server implementation. Keywords do not 538 begin with "\". Servers MAY permit the client to define new keywords 539 in the mailbox (see the description of the PERMANENTFLAGS response 540 code for more information). Some keywords that start with "$" are 541 also defined in this specification. 543 This document defines several keywords that were not originally 544 defined in RFC 3501, but which were found to be useful by client 545 implementations. These keywords SHOULD be supported (i.e. allowed in 546 SEARCH, allowed and preserved in APPEND, COPY, MOVE commands) by 547 server implementations: 549 $Forwarded Message has been forwarded to another email address, 550 embedded within or attached to a new message. An email client 551 sets this keyword when it successfully forwards the message to 552 another email address. Typical usage of this keyword is to show a 553 different (or additional) icon for a message that has been 554 forwarded. Once set, the flag SHOULD NOT be cleared. 556 $MDNSent Message Disposition Notification [RFC8098] was generated 557 and sent for this message. See [RFC3503] for more details on how 558 this keyword is used. 560 $Junk The user (or a delivery agent on behalf of the user) may 561 choose to mark a message as definitely containing junk ($Junk; see 562 also the related keyword $NotJunk). The $Junk keyword can be used 563 to mark (and potentially move/delete messages later), group or 564 hide undesirable messages. See [IMAP-KEYWORDS-REG] for more 565 information. 567 $NotJunk The user (or a delivery agent on behalf of the user) may 568 choose to mark a message as definitely not containing junk 569 ($NotJunk; see also the related keyword $Junk). The $NotJunk 570 keyword can be used to mark, group or show messages that the user 571 wants to see. See [IMAP-KEYWORDS-REG] for more information. 573 $Phishing The $Phishing keyword can be used by a delivery agent to 574 mark a message as highly likely to be a phishing email. An email 575 that's determined to be a phishing email by the delivery agent 576 should also be considered a junk email and have the appropriate 577 junk filtering applied, including setting the $Junk flag and 578 placing in the \Junk special-use mailbox (see Section 7.2.3) if 579 available. 580 If both the $Phishing flag and the $Junk flag are set, the user 581 agent should display an additional warning message to the user. 582 User agents should not use the term "phishing" in their warning 583 message as most users do not understand this term. Phrasing of 584 the form "this message may be trying to steal your personal 585 information" is recommended. Additionally the user agent may 586 display a warning when clicking on any hyperlinks within the 587 message. 588 The requirement for both $Phishing and $Junk to be set before a 589 user agent displays a warning is for better backwards 590 compatibility with existing clients that understand the $Junk flag 591 but not the $Phishing flag. This so that when an unextended 592 client removes the $Junk flag, an extended client will also show 593 the correct state. See [IMAP-KEYWORDS-REG] for more information. 595 $Junk and $NotJunk are mutually exclusive. If more than one of them 596 is set for a message, the client MUST treat this as if none of them 597 is set and SHOULD unset both of them on the IMAP server. 599 Other registered keywords can be found in the "IMAP and JMAP 600 Keywords" registry [IMAP-KEYWORDS-REG]. New keywords SHOULD be 601 registered in this registry using the procedure specified in 602 [RFC5788]. 604 A flag can be permanent or session-only on a per-flag basis. 605 Permanent flags are those which the client can add or remove from the 606 message flags permanently; that is, concurrent and subsequent 607 sessions will see any change in permanent flags. Changes to session 608 flags are valid only in that session. 610 2.3.3. Internal Date Message Attribute 612 The internal date and time of the message on the server. This is not 613 the date and time in the [RFC-5322] header, but rather a date and 614 time which reflects when the message was received. In the case of 615 messages delivered via [SMTP], this SHOULD be the date and time of 616 final delivery of the message as defined by [SMTP]. In the case of 617 messages delivered by the IMAP4rev2 COPY or MOVE command, this SHOULD 618 be the internal date and time of the source message. In the case of 619 messages delivered by the IMAP4rev2 APPEND command, this SHOULD be 620 the date and time as specified in the APPEND command description. 621 All other cases are implementation defined. 623 2.3.4. [RFC-5322] Size Message Attribute 625 The number of octets in the message, as expressed in [RFC-5322] 626 format. 628 2.3.5. Envelope Structure Message Attribute 630 A parsed representation of the [RFC-5322] header of the message. 631 Note that the IMAP Envelope structure is not the same as an [SMTP] 632 envelope. 634 2.3.6. Body Structure Message Attribute 636 A parsed representation of the [MIME-IMB] body structure information 637 of the message. 639 2.4. Message Texts 641 In addition to being able to fetch the full [RFC-5322] text of a 642 message, IMAP4rev2 permits the fetching of portions of the full 643 message text. Specifically, it is possible to fetch the [RFC-5322] 644 message header, [RFC-5322] message body, a [MIME-IMB] body part, or a 645 [MIME-IMB] header. 647 3. State and Flow Diagram 649 Once the connection between client and server is established, an 650 IMAP4rev2 connection is in one of four states. The initial state is 651 identified in the server greeting. Most commands are only valid in 652 certain states. It is a protocol error for the client to attempt a 653 command while the connection is in an inappropriate state, and the 654 server will respond with a BAD or NO (depending upon server 655 implementation) command completion result. 657 3.1. Not Authenticated State 659 In the not authenticated state, the client MUST supply authentication 660 credentials before most commands will be permitted. This state is 661 entered when a connection starts unless the connection has been pre- 662 authenticated. 664 3.2. Authenticated State 666 In the authenticated state, the client is authenticated and MUST 667 select a mailbox to access before commands that affect messages will 668 be permitted. This state is entered when a pre-authenticated 669 connection starts, when acceptable authentication credentials have 670 been provided, after an error in selecting a mailbox, or after a 671 successful CLOSE command. 673 3.3. Selected State 675 In a selected state, a mailbox has been selected to access. This 676 state is entered when a mailbox has been successfully selected. 678 3.4. Logout State 680 In the logout state, the connection is being terminated. This state 681 can be entered as a result of a client request (via the LOGOUT 682 command) or by unilateral action on the part of either the client or 683 server. 685 If the client requests the logout state, the server MUST send an 686 untagged BYE response and a tagged OK response to the LOGOUT command 687 before the server closes the connection; and the client MUST read the 688 tagged OK response to the LOGOUT command before the client closes the 689 connection. 691 A server SHOULD NOT unilaterally close the connection without sending 692 an untagged BYE response that contains the reason for having done so. 693 A client SHOULD NOT unilaterally close the connection, and instead 694 SHOULD issue a LOGOUT command. If the server detects that the client 695 has unilaterally closed the connection, the server MAY omit the 696 untagged BYE response and simply close its connection. 698 +----------------------+ 699 |connection established| 700 +----------------------+ 701 || 702 \/ 703 +--------------------------------------+ 704 | server greeting | 705 +--------------------------------------+ 706 || (1) || (2) || (3) 707 \/ || || 708 +-----------------+ || || 709 |Not Authenticated| || || 710 +-----------------+ || || 711 || (7) || (4) || || 712 || \/ \/ || 713 || +----------------+ || 714 || | Authenticated |<=++ || 715 || +----------------+ || || 716 || || (7) || (5) || (6) || 717 || || \/ || || 718 || || +--------+ || || 719 || || |Selected|==++ || 720 || || +--------+ || 721 || || || (7) || 722 \/ \/ \/ \/ 723 +--------------------------------------+ 724 | Logout | 725 +--------------------------------------+ 726 || 727 \/ 728 +-------------------------------+ 729 |both sides close the connection| 730 +-------------------------------+ 732 (1) connection without pre-authentication (OK greeting) 733 (2) pre-authenticated connection (PREAUTH greeting) 734 (3) rejected connection (BYE greeting) 735 (4) successful LOGIN or AUTHENTICATE command 736 (5) successful SELECT or EXAMINE command 737 (6) CLOSE command, unsolicited CLOSED response code or 738 failed SELECT or EXAMINE command 739 (7) LOGOUT command, server shutdown, or connection closed 741 4. Data Formats 743 IMAP4rev2 uses textual commands and responses. Data in IMAP4rev2 can 744 be in one of several forms: atom, number, string, parenthesized list, 745 or NIL. Note that a particular data item may take more than one 746 form; for example, a data item defined as using "astring" syntax may 747 be either an atom or a string. 749 4.1. Atom 751 An atom consists of one or more non-special characters. 753 4.1.1. Sequence set and UID set 755 A set of messages can be referenced by a sequence set containing 756 either message sequence numbers or unique identifiers. See Section 9 757 for details. Sequence sets can contain ranges (e.g. "5:50"), an 758 enumeration of specific message/UID numbers, a special symbol "*", or 759 a combination of the above. 761 A "UID set" is similar to the sequence set of unique identifiers; 762 however, the "*" value for a sequence number is not permitted. 764 4.2. Number 766 A number consists of one or more digit characters, and represents a 767 numeric value. 769 4.3. String 771 A string is in one of three forms: synchonizing literal, non- 772 synchronizing literal or quoted string. The synchronizing literal 773 form is the general form of string. The non-synchronizing literal 774 form is also the general form, but has length limitation. The quoted 775 string form is an alternative that avoids the overhead of processing 776 a literal at the cost of limitations of characters which may be used. 778 When the distinction between synchronizing and non-synchronizing 779 literals is not important, this document just uses the term 780 "literal". 782 A synchronizing literal is a sequence of zero or more octets 783 (including CR and LF), prefix-quoted with an octet count in the form 784 of an open brace ("{"), the number of octets, close brace ("}"), and 785 CRLF. In the case of synchronizing literals transmitted from server 786 to client, the CRLF is immediately followed by the octet data. In 787 the case of synchronizing literals transmitted from client to server, 788 the client MUST wait to receive a command continuation request 789 (described later in this document) before sending the octet data (and 790 the remainder of the command). 792 The non-synchronizing literal is an alternate form of synchronizing 793 literal, and it may appear in communication from client to server 794 instead of the synchonizing form of literal. The non-synchronizing 795 literal form MUST NOT be sent from server to client. The non- 796 synchronizing literal is distinguished from the synchronizing literal 797 by having a plus ("+") between the octet count and the closing brace 798 ("}"). The server does not generate a command continuation request 799 in response to a non-synchronizing literal, and clients are not 800 required to wait before sending the octets of a non- synchronizing 801 literal. Non-synchronizing literals MUST NOT be larger than 4096 802 octets. Any literal larger than 4096 bytes MUST be sent as a 803 synchronizing literal. (Non-synchronizing literals defined in this 804 document are the same as non-synchronizing literals defined by the 805 LITERAL- extension from [RFC7888]. See that document for details on 806 how to handle invalid non-synchronizing literals longer than 4096 807 octets and for interaction with other IMAP extensions.) 809 A quoted string is a sequence of zero or more Unicode characters, 810 excluding CR and LF, encoded in UTF-8, with double quote (<">) 811 characters at each end. 813 The empty string is represented as "" (a quoted string with zero 814 characters between double quotes), as {0} followed by CRLF (a 815 synchronizing literal with an octet count of 0) or as {0+} followed 816 by CRLF (a non-synchronizing literal with an octet count of 0). 818 Note: Even if the octet count is 0, a client transmitting a 819 synchronizing literal MUST wait to receive a command continuation 820 request. 822 4.3.1. 8-bit and Binary Strings 824 8-bit textual and binary mail is supported through the use of a 825 [MIME-IMB] content transfer encoding. IMAP4rev2 implementations MAY 826 transmit 8-bit or multi-octet characters in literals, but SHOULD do 827 so only when the [CHARSET] is identified. 829 IMAP4rev2 is compatible with [I18N-HDRS]. As a result, the 830 identified charset for header-field values with 8-bit content is 831 UTF-8 [UTF-8]. IMAP4rev2 implementations MUST accept and MAY 832 transmit [UTF-8] text in quoted-strings as long as the string does 833 not contain NUL, CR, or LF. This differs from IMAP4rev1 834 implementations. 836 Although a BINARY content transfer encoding is defined, unencoded 837 binary strings are not permitted, unless returned in a in 838 response to BINARY.PEEK[]<> or 839 BINARY[]<> FETCH data item. A "binary 840 string" is any string with NUL characters. A string with an 841 excessive amount of CTL characters MAY also be considered to be 842 binary. Unless returned in response to BINARY.PEEK[...]/BINARY[...] 843 FETCH, client and server implementations MUST encode binary data into 844 a textual form, such as BASE64, before transmitting the data. 846 4.4. Parenthesized List 848 Data structures are represented as a "parenthesized list"; a sequence 849 of data items, delimited by space, and bounded at each end by 850 parentheses. A parenthesized list can contain other parenthesized 851 lists, using multiple levels of parentheses to indicate nesting. 853 The empty list is represented as () -- a parenthesized list with no 854 members. 856 4.5. NIL 858 The special form "NIL" represents the non-existence of a particular 859 data item that is represented as a string or parenthesized list, as 860 distinct from the empty string "" or the empty parenthesized list (). 862 Note: NIL is never used for any data item which takes the form of 863 an atom. For example, a mailbox name of "NIL" is a mailbox named 864 NIL as opposed to a non-existent mailbox name. This is because 865 mailbox uses "astring" syntax which is an atom or a string. 866 Conversely, an addr-name of NIL is a non-existent personal name, 867 because addr-name uses "nstring" syntax which is NIL or a string, 868 but never an atom. 870 Examples: 872 The following LIST response: 874 * LIST () "/" NIL 876 is equivalent to: 877 * LIST () "/" "NIL" 879 as LIST response ABNF is using astring for mailbox name. 881 However, the following response 883 * FETCH 1 (BODY[1] NIL) 885 is not equivalent to: 886 * FETCH 1 (BODY[1] "NIL") 887 The former means absence of the body part, while the latter 888 means that it contains literal sequence of characters "NIL". 890 5. Operational Considerations 892 The following rules are listed here to ensure that all IMAP4rev2 893 implementations interoperate properly. 895 5.1. Mailbox Naming 897 In IMAP4rev2, Mailbox names are encoded in Net-Unicode [NET-UNICODE] 898 (this differs from IMAP4rev1). Client implementations MAY attempt to 899 create Net-Unicode mailbox names, and MUST interpret any 8-bit 900 mailbox names returned by LIST as [NET-UNICODE]. Server 901 implementations MUST prohibit the creation of 8-bit mailbox names 902 that do not comply with Net-Unicode. However, servers MAY accept a 903 de-normalized UTF-8 mailbox name and convert it to Unicode 904 normalization form "NFC" (as per Net-Unicode requirements) prior to 905 mailbox creation. Servers that choose to accept such de-normalized 906 UTF-8 mailbox names MUST accept them in all IMAP commands that have a 907 mailbox name parameter. In particular SELECT must open the 908 same mailbox that was successfully created with CREATE , even 909 if is a de-normalized UTF-8 mailbox name. 911 The case-insensitive mailbox name INBOX is a special name reserved to 912 mean "the primary mailbox for this user on this server". (Note that 913 this special name may not exist on some servers for some users, for 914 example if the user has no access to personal namespace.) The 915 interpretation of all other names is implementation-dependent. 917 In particular, this specification takes no position on case 918 sensitivity in non-INBOX mailbox names. Some server implementations 919 are fully case-sensitive in ASCII range; others preserve case of a 920 newly-created name but otherwise are case-insensitive; and yet others 921 coerce names to a particular case. Client implementations must be 922 able to interact with any of these. 924 There are certain client considerations when creating a new mailbox 925 name: 927 1. Any character which is one of the atom-specials (see the Formal 928 Syntax) will require that the mailbox name be represented as a 929 quoted string or literal. 931 2. CTL and other non-graphic characters are difficult to represent 932 in a user interface and are best avoided. Servers MAY refuse to 933 create mailbox names containing Unicode CTL characters. 935 3. Although the list-wildcard characters ("%" and "*") are valid in 936 a mailbox name, it is difficult to use such mailbox names with 937 the LIST command due to the conflict with wildcard 938 interpretation. 940 4. Usually, a character (determined by the server implementation) is 941 reserved to delimit levels of hierarchy. 943 5. Two characters, "#" and "&", have meanings by convention, and 944 should be avoided except when used in that convention. See 945 Section 5.1.2.1 and Appendix A.1 respectively. 947 5.1.1. Mailbox Hierarchy Naming 949 If it is desired to export hierarchical mailbox names, mailbox names 950 MUST be left-to-right hierarchical using a single character to 951 separate levels of hierarchy. The same hierarchy separator character 952 is used for all levels of hierarchy within a single name. 954 5.1.2. Namespaces 956 Personal Namespace: A namespace that the server considers within the 957 personal scope of the authenticated user on a particular connection. 958 Typically, only the authenticated user has access to mailboxes in 959 their Personal Namespace. It is the part of the namespace that 960 belongs to the user that is allocated for mailboxes. If an INBOX 961 exists for a user, it MUST appear within the user's personal 962 namespace. In the typical case, there SHOULD be only one Personal 963 Namespace on a server. 965 Other Users' Namespace: A namespace that consists of mailboxes from 966 the Personal Namespaces of other users. To access mailboxes in the 967 Other Users' Namespace, the currently authenticated user MUST be 968 explicitly granted access rights. For example, it is common for a 969 manager to grant to their secretary access rights to their mailbox. 970 In the typical case, there SHOULD be only one Other Users' Namespace 971 on a server. 973 Shared Namespace: A namespace that consists of mailboxes that are 974 intended to be shared amongst users and do not exist within a user's 975 Personal Namespace. 977 The namespaces a server uses MAY differ on a per-user basis. 979 5.1.2.1. Historic Mailbox Namespace Naming Convention 981 By convention, the first hierarchical element of any mailbox name 982 which begins with "#" identifies the "namespace" of the remainder of 983 the name. This makes it possible to disambiguate between different 984 types of mailbox stores, each of which have their own namespaces. 986 For example, implementations which offer access to USENET 987 newsgroups MAY use the "#news" namespace to partition the USENET 988 newsgroup namespace from that of other mailboxes. Thus, the 989 comp.mail.misc newsgroup would have a mailbox name of 990 "#news.comp.mail.misc", and the name "comp.mail.misc" can refer to 991 a different object (e.g., a user's private mailbox). 993 Namespaces that include the "#" character are not IMAP URL [IMAP-URL] 994 friendly requiring the "#" character to be represented as %23 when 995 within URLs. As such, server implementers MAY instead consider using 996 namespace prefixes that do not contain the "#" character. 998 5.1.2.2. Common namespace models 1000 Previous version of this protocol does not define a default server 1001 namespace. Two common namespace models have evolved: 1003 The "Personal Mailbox" model, in which the default namespace that is 1004 presented consists of only the user's personal mailboxes. To access 1005 shared mailboxes, the user must use an escape mechanism to reach 1006 another namespace. 1008 The "Complete Hierarchy" model, in which the default namespace that 1009 is presented includes the user's personal mailboxes along with any 1010 other mailboxes they have access to. 1012 5.2. Mailbox Size and Message Status Updates 1014 At any time, a server can send data that the client did not request. 1015 Sometimes, such behavior is REQUIRED. For example, agents other than 1016 the server MAY add messages to the mailbox (e.g., new message 1017 delivery), change the flags of the messages in the mailbox (e.g., 1018 simultaneous access to the same mailbox by multiple agents), or even 1019 remove messages from the mailbox. A server MUST send mailbox size 1020 updates automatically if a mailbox size change is observed during the 1021 processing of a command. A server SHOULD send message flag updates 1022 automatically, without requiring the client to request such updates 1023 explicitly. 1025 Special rules exist for server notification of a client about the 1026 removal of messages to prevent synchronization errors; see the 1027 description of the EXPUNGE response for more detail. In particular, 1028 it is NOT permitted to send an EXISTS response that would reduce the 1029 number of messages in the mailbox; only the EXPUNGE response can do 1030 this. 1032 Regardless of what implementation decisions a client makes on 1033 remembering data from the server, a client implementation MUST record 1034 mailbox size updates. It MUST NOT assume that any command after the 1035 initial mailbox selection will return the size of the mailbox. 1037 5.3. Response when no Command in Progress 1039 Server implementations are permitted to send an untagged response 1040 (except for EXPUNGE) while there is no command in progress. Server 1041 implementations that send such responses MUST deal with flow control 1042 considerations. Specifically, they MUST either (1) verify that the 1043 size of the data does not exceed the underlying transport's available 1044 window size, or (2) use non-blocking writes. 1046 5.4. Autologout Timer 1048 If a server has an inactivity autologout timer that applies to 1049 sessions after authentication, the duration of that timer MUST be at 1050 least 30 minutes. The receipt of ANY command from the client during 1051 that interval SHOULD suffice to reset the autologout timer. 1053 5.5. Multiple Commands in Progress (Command Pipelining) 1055 The client MAY send another command without waiting for the 1056 completion result response of a command, subject to ambiguity rules 1057 (see below) and flow control constraints on the underlying data 1058 stream. Similarly, a server MAY begin processing another command 1059 before processing the current command to completion, subject to 1060 ambiguity rules. However, any command continuation request responses 1061 and command continuations MUST be negotiated before any subsequent 1062 command is initiated. 1064 The exception is if an ambiguity would result because of a command 1065 that would affect the results of other commands. If the server 1066 detects a possible ambiguity, it MUST execute commands to completion 1067 in the order given by the client. 1069 The most obvious example of ambiguity is when a command would affect 1070 the results of another command, e.g., a FETCH of a message's flags 1071 and a STORE of that same message's flags. 1073 A non-obvious ambiguity occurs with commands that permit an untagged 1074 EXPUNGE response (commands other than FETCH, STORE, and SEARCH), 1075 since an untagged EXPUNGE response can invalidate sequence numbers in 1076 a subsequent command. This is not a problem for FETCH, STORE, or 1077 SEARCH commands because servers are prohibited from sending EXPUNGE 1078 responses while any of those commands are in progress. Therefore, if 1079 the client sends any command other than FETCH, STORE, or SEARCH, it 1080 MUST wait for the completion result response before sending a command 1081 with message sequence numbers. 1083 Note: EXPUNGE responses are permitted while UID FETCH, UID STORE, 1084 and UID SEARCH are in progress. If the client sends a UID 1085 command, it MUST wait for a completion result response before 1086 sending a command which uses message sequence numbers (this may 1087 include UID SEARCH). Any message sequence numbers in an argument 1088 to UID SEARCH are associated with messages prior to the effect of 1089 any untagged EXPUNGE returned by the UID SEARCH. 1091 For example, the following non-waiting command sequences are invalid: 1093 FETCH + NOOP + STORE 1095 STORE + COPY + FETCH 1097 COPY + COPY 1099 The following are examples of valid non-waiting command sequences: 1101 FETCH + STORE + SEARCH + NOOP 1103 STORE + COPY + EXPUNGE 1105 UID SEARCH + UID SEARCH may be valid or invalid as a non-waiting 1106 command sequence, depending upon whether or not the second UID 1107 SEARCH contains message sequence numbers. 1109 Use of SEARCH result variable (see Section 6.4.4.1) creates direct 1110 dependency between two commands. See Section 6.4.4.2 for more 1111 considerations about pipelining such dependent commands. 1113 6. Client Commands 1115 IMAP4rev2 commands are described in this section. Commands are 1116 organized by the state in which the command is permitted. Commands 1117 which are permitted in multiple states are listed in the minimum 1118 permitted state (for example, commands valid in authenticated and 1119 selected state are listed in the authenticated state commands). 1121 Command arguments, identified by "Arguments:" in the command 1122 descriptions below, are described by function, not by syntax. The 1123 precise syntax of command arguments is described in the Formal Syntax 1124 (Section 9). 1126 Some commands cause specific server responses to be returned; these 1127 are identified by "Responses:" in the command descriptions below. 1128 See the response descriptions in the Responses section for 1129 information on these responses, and the Formal Syntax section for the 1130 precise syntax of these responses. It is possible for server data to 1131 be transmitted as a result of any command. Thus, commands that do 1132 not specifically require server data specify "no specific responses 1133 for this command" instead of "none". 1135 The "Result:" in the command description refers to the possible 1136 tagged status responses to a command, and any special interpretation 1137 of these status responses. 1139 The state of a connection is only changed by successful commands 1140 which are documented as changing state. A rejected command (BAD 1141 response) never changes the state of the connection or of the 1142 selected mailbox. A failed command (NO response) generally does not 1143 change the state of the connection or of the selected mailbox; the 1144 exception being the SELECT and EXAMINE commands. 1146 6.1. Client Commands - Any State 1148 The following commands are valid in any state: CAPABILITY, NOOP, and 1149 LOGOUT. 1151 6.1.1. CAPABILITY Command 1153 Arguments: none 1155 Responses: REQUIRED untagged response: CAPABILITY 1156 Result: OK - capability completed 1157 BAD - command unknown or arguments invalid 1159 The CAPABILITY command requests a listing of capabilities that the 1160 server supports. The server MUST send a single untagged CAPABILITY 1161 response with "IMAP4rev2" as one of the listed capabilities before 1162 the (tagged) OK response. 1164 A capability name which begins with "AUTH=" indicates that the server 1165 supports that particular authentication mechanism. All such names 1166 are, by definition, part of this specification. For example, the 1167 authorization capability for an experimental "blurdybloop" 1168 authenticator would be "AUTH=XBLURDYBLOOP" and not 1169 "XAUTH=BLURDYBLOOP" or "XAUTH=XBLURDYBLOOP". 1171 Other capability names refer to extensions, revisions, or amendments 1172 to this specification. See the documentation of the CAPABILITY 1173 response for additional information. No capabilities, beyond the 1174 base IMAP4rev2 set defined in this specification, are enabled without 1175 explicit client action to invoke the capability. 1177 Client and server implementations MUST implement the STARTTLS, 1178 LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) capabilities. 1179 See the Security Considerations section for important information. 1181 See the section entitled "Client Commands - Experimental/Expansion" 1182 for information about the form of site or implementation-specific 1183 capabilities. 1185 Example: C: abcd CAPABILITY 1186 S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI 1187 LOGINDISABLED 1188 S: abcd OK CAPABILITY completed 1189 C: efgh STARTTLS 1190 S: efgh OK STARTLS completed 1191 1192 C: ijkl CAPABILITY 1193 S: * CAPABILITY IMAP4rev2 AUTH=GSSAPI AUTH=PLAIN 1194 S: ijkl OK CAPABILITY completed 1196 6.1.2. NOOP Command 1198 Arguments: none 1200 Responses: no specific responses for this command (but see below) 1202 Result: OK - noop completed 1203 BAD - command unknown or arguments invalid 1205 The NOOP command always succeeds. It does nothing. 1207 Since any command can return a status update as untagged data, the 1208 NOOP command can be used as a periodic poll for new messages or 1209 message status updates during a period of inactivity (the IDLE 1210 command Section 6.3.13 should be used instead of NOOP if real-time 1211 updates to mailbox state are desirable). The NOOP command can also 1212 be used to reset any inactivity autologout timer on the server. 1214 Example: C: a002 NOOP 1215 S: a002 OK NOOP completed 1216 . . . 1217 C: a047 NOOP 1218 S: * 22 EXPUNGE 1219 S: * 23 EXISTS 1220 S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted)) 1221 S: a047 OK NOOP completed 1223 6.1.3. LOGOUT Command 1225 Arguments: none 1227 Responses: REQUIRED untagged response: BYE 1229 Result: OK - logout completed 1230 BAD - command unknown or arguments invalid 1232 The LOGOUT command informs the server that the client is done with 1233 the connection. The server MUST send a BYE untagged response before 1234 the (tagged) OK response, and then close the network connection. 1236 Example: C: A023 LOGOUT 1237 S: * BYE IMAP4rev2 Server logging out 1238 S: A023 OK LOGOUT completed 1239 (Server and client then close the connection) 1241 6.2. Client Commands - Not Authenticated State 1243 In the not authenticated state, the AUTHENTICATE or LOGIN command 1244 establishes authentication and enters the authenticated state. The 1245 AUTHENTICATE command provides a general mechanism for a variety of 1246 authentication techniques, privacy protection, and integrity 1247 checking; whereas the LOGIN command uses a traditional user name and 1248 plaintext password pair and has no means of establishing privacy 1249 protection or integrity checking. 1251 The STARTTLS command is an alternate form of establishing session 1252 privacy protection and integrity checking, but does not by itself 1253 establish authentication or enter the authenticated state. 1255 Server implementations MAY allow access to certain mailboxes without 1256 establishing authentication. This can be done by means of the 1257 ANONYMOUS [SASL] authenticator described in [ANONYMOUS]. An older 1258 convention is a LOGIN command using the userid "anonymous"; in this 1259 case, a password is required although the server may choose to accept 1260 any password. The restrictions placed on anonymous users are 1261 implementation-dependent. 1263 Once authenticated (including as anonymous), it is not possible to 1264 re-enter not authenticated state. 1266 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1267 the following commands are valid in the not authenticated state: 1268 STARTTLS, AUTHENTICATE and LOGIN. See the Security Considerations 1269 section for important information about these commands. 1271 6.2.1. STARTTLS Command 1273 Arguments: none 1275 Responses: no specific response for this command 1277 Result: OK - starttls completed, begin TLS negotiation 1278 BAD - command unknown or arguments invalid 1280 A [TLS] negotiation begins immediately after the CRLF at the end of 1281 the tagged OK response from the server. Once a client issues a 1282 STARTTLS command, it MUST NOT issue further commands until a server 1283 response is seen and the [TLS] negotiation is complete. 1285 The server remains in the non-authenticated state, even if client 1286 credentials are supplied during the [TLS] negotiation. This does not 1287 preclude an authentication mechanism such as EXTERNAL (defined in 1288 [SASL]) from using client identity determined by the [TLS] 1289 negotiation. 1291 Once [TLS] has been started, the client MUST discard cached 1292 information about server capabilities and SHOULD re-issue the 1293 CAPABILITY command. This is necessary to protect against man-in- 1294 the-middle attacks which alter the capabilities list prior to 1295 STARTTLS. The server MAY advertise different capabilities, and in 1296 particular SHOULD NOT advertise the STARTTLS capability, after a 1297 successful STARTTLS command. 1299 Example: C: a001 CAPABILITY 1300 S: * CAPABILITY IMAP4rev2 STARTTLS LOGINDISABLED 1301 S: a001 OK CAPABILITY completed 1302 C: a002 STARTTLS 1303 S: a002 OK Begin TLS negotiation now 1304 1305 C: a003 CAPABILITY 1306 S: * CAPABILITY IMAP4rev2 AUTH=PLAIN 1307 S: a003 OK CAPABILITY completed 1308 C: a004 LOGIN joe password 1309 S: a004 OK LOGIN completed 1311 6.2.2. AUTHENTICATE Command 1313 Arguments: SASL authentication mechanism name 1314 OPTIONAL initial response 1316 Responses: continuation data can be requested 1318 Result: OK - authenticate completed, now in authenticated state 1319 NO - authenticate failure: unsupported authentication 1320 mechanism, credentials rejected 1321 BAD - command unknown or arguments invalid, 1322 authentication exchange cancelled 1324 The AUTHENTICATE command indicates a [SASL] authentication mechanism 1325 to the server. If the server supports the requested authentication 1326 mechanism, it performs an authentication protocol exchange to 1327 authenticate and identify the client. It MAY also negotiate an 1328 OPTIONAL security layer for subsequent protocol interactions. If the 1329 requested authentication mechanism is not supported, the server 1330 SHOULD reject the AUTHENTICATE command by sending a tagged NO 1331 response. 1333 The AUTHENTICATE command supports the optional "initial response" 1334 feature defined in Section 5.1 of [SASL]. The client doesn't need to 1335 use it. If a SASL mechanism supports "initial response", but it is 1336 not specified by the client, the server handles this as specified in 1337 Section 3 of [SASL]. 1339 The service name specified by this protocol's profile of [SASL] is 1340 "imap". 1342 The authentication protocol exchange consists of a series of server 1343 challenges and client responses that are specific to the 1344 authentication mechanism. A server challenge consists of a command 1345 continuation request response with the "+" token followed by a BASE64 1346 encoded (see Section 4 of [RFC4648]) string. The client response 1347 consists of a single line consisting of a BASE64 encoded string. If 1348 the client wishes to cancel an authentication exchange, it issues a 1349 line consisting of a single "*". If the server receives such a 1350 response, or if it receives an invalid BASE64 string (e.g. 1351 characters outside the BASE64 alphabet, or non-terminal "="), it MUST 1352 reject the AUTHENTICATE command by sending a tagged BAD response. 1354 As with any other client response, this initial response MUST be 1355 encoded as BASE64. It also MUST be transmitted outside of a quoted 1356 string or literal. To send a zero-length initial response, the 1357 client MUST send a single pad character ("="). This indicates that 1358 the response is present, but is a zero-length string. 1360 When decoding the BASE64 data in the initial response, decoding 1361 errors MUST be treated as in any normal SASL client response, i.e. 1362 with a tagged BAD response. In particular, the server should check 1363 for any characters not explicitly allowed by the BASE64 alphabet, as 1364 well as any sequence of BASE64 characters that contains the pad 1365 character ('=') anywhere other than the end of the string (e.g., 1366 "=AAA" and "AAA=BBB" are not allowed). 1368 If the client uses an initial response with a SASL mechanism that 1369 does not support an initial response, the server MUST reject the 1370 command with a tagged BAD response. 1372 If a security layer is negotiated through the [SASL] authentication 1373 exchange, it takes effect immediately following the CRLF that 1374 concludes the authentication exchange for the client, and the CRLF of 1375 the tagged OK response for the server. 1377 While client and server implementations MUST implement the 1378 AUTHENTICATE command itself, it is not required to implement any 1379 authentication mechanisms other than the PLAIN mechanism described in 1380 [PLAIN]. Also, an authentication mechanism is not required to 1381 support any security layers. 1383 Note: a server implementation MUST implement a configuration in 1384 which it does NOT permit any plaintext password mechanisms, unless 1385 either the STARTTLS command has been negotiated or some other 1386 mechanism that protects the session from password snooping has 1387 been provided. Server sites SHOULD NOT use any configuration 1388 which permits a plaintext password mechanism without such a 1389 protection mechanism against password snooping. Client and server 1390 implementations SHOULD implement additional [SASL] mechanisms that 1391 do not use plaintext passwords, such the GSSAPI mechanism 1392 described in [SASL] and/or the SCRAM-SHA-256/SCRAM-SHA-256-PLUS 1393 [SCRAM-SHA-256] mechanisms. 1395 Servers and clients can support multiple authentication mechanisms. 1396 The server SHOULD list its supported authentication mechanisms in the 1397 response to the CAPABILITY command so that the client knows which 1398 authentication mechanisms to use. 1400 A server MAY include a CAPABILITY response code in the tagged OK 1401 response of a successful AUTHENTICATE command in order to send 1402 capabilities automatically. It is unnecessary for a client to send a 1403 separate CAPABILITY command if it recognizes these automatic 1404 capabilities. This should only be done if a security layer was not 1405 negotiated by the AUTHENTICATE command, because the tagged OK 1406 response as part of an AUTHENTICATE command is not protected by 1407 encryption/integrity checking. [SASL] requires the client to re- 1408 issue a CAPABILITY command in this case. The server MAY advertise 1409 different capabilities after a successful AUTHENTICATE command. 1411 If an AUTHENTICATE command fails with a NO response, the client MAY 1412 try another authentication mechanism by issuing another AUTHENTICATE 1413 command. It MAY also attempt to authenticate by using the LOGIN 1414 command (see Section 6.2.3 for more detail). In other words, the 1415 client MAY request authentication types in decreasing order of 1416 preference, with the LOGIN command as a last resort. 1418 The authorization identity passed from the client to the server 1419 during the authentication exchange is interpreted by the server as 1420 the user name whose privileges the client is requesting. 1422 Example: S: * OK IMAP4rev2 Server 1423 C: A001 AUTHENTICATE GSSAPI 1424 S: + 1425 C: YIIB+wYJKoZIhvcSAQICAQBuggHqMIIB5qADAgEFoQMCAQ6iBw 1426 MFACAAAACjggEmYYIBIjCCAR6gAwIBBaESGxB1Lndhc2hpbmd0 1427 b24uZWR1oi0wK6ADAgEDoSQwIhsEaW1hcBsac2hpdmFtcy5jYW 1428 Mud2FzaGluZ3Rvbi5lZHWjgdMwgdCgAwIBAaEDAgEDooHDBIHA 1429 cS1GSa5b+fXnPZNmXB9SjL8Ollj2SKyb+3S0iXMljen/jNkpJX 1430 AleKTz6BQPzj8duz8EtoOuNfKgweViyn/9B9bccy1uuAE2HI0y 1431 C/PHXNNU9ZrBziJ8Lm0tTNc98kUpjXnHZhsMcz5Mx2GR6dGknb 1432 I0iaGcRerMUsWOuBmKKKRmVMMdR9T3EZdpqsBd7jZCNMWotjhi 1433 vd5zovQlFqQ2Wjc2+y46vKP/iXxWIuQJuDiisyXF0Y8+5GTpAL 1434 pHDc1/pIGmMIGjoAMCAQGigZsEgZg2on5mSuxoDHEA1w9bcW9n 1435 FdFxDKpdrQhVGVRDIzcCMCTzvUboqb5KjY1NJKJsfjRQiBYBdE 1436 NKfzK+g5DlV8nrw81uOcP8NOQCLR5XkoMHC0Dr/80ziQzbNqhx 1437 O6652Npft0LQwJvenwDI13YxpwOdMXzkWZN/XrEqOWp6GCgXTB 1438 vCyLWLlWnbaUkZdEYbKHBPjd8t/1x5Yg== 1439 S: + YGgGCSqGSIb3EgECAgIAb1kwV6ADAgEFoQMCAQ+iSzBJoAMC 1440 AQGiQgRAtHTEuOP2BXb9sBYFR4SJlDZxmg39IxmRBOhXRKdDA0 1441 uHTCOT9Bq3OsUTXUlk0CsFLoa8j+gvGDlgHuqzWHPSQg== 1442 C: 1443 S: + YDMGCSqGSIb3EgECAgIBAAD/////6jcyG4GE3KkTzBeBiVHe 1444 ceP2CWY0SR0fAQAgAAQEBAQ= 1445 C: YDMGCSqGSIb3EgECAgIBAAD/////3LQBHXTpFfZgrejpLlLImP 1446 wkhbfa2QteAQAgAG1yYwE= 1447 S: A001 OK GSSAPI authentication successful 1449 Note: The line breaks within server challenges and client responses 1450 are for editorial clarity and are not in real authenticators. 1452 6.2.3. LOGIN Command 1454 Arguments: user name 1455 password 1457 Responses: no specific responses for this command 1459 Result: OK - login completed, now in authenticated state 1460 NO - login failure: user name or password rejected 1461 BAD - command unknown or arguments invalid 1463 The LOGIN command identifies the client to the server and carries the 1464 plaintext password authenticating this user. 1466 A server MAY include a CAPABILITY response code in the tagged OK 1467 response to a successful LOGIN command in order to send capabilities 1468 automatically. It is unnecessary for a client to send a separate 1469 CAPABILITY command if it recognizes these automatic capabilities. 1471 Example: C: a001 LOGIN SMITH SESAME 1472 S: a001 OK LOGIN completed 1474 Note: Use of the LOGIN command over an insecure network (such as the 1475 Internet) is a security risk, because anyone monitoring network 1476 traffic can obtain plaintext passwords. The LOGIN command SHOULD NOT 1477 be used except as a last resort, and it is recommended that client 1478 implementations have a means to disable any automatic use of the 1479 LOGIN command. 1481 Unless either the client is accessing IMAP service on IMAPS port 1482 [RFC8314], the STARTTLS command has been negotiated or some other 1483 mechanism that protects the session from password snooping has been 1484 provided, a server implementation MUST implement a configuration in 1485 which it advertises the LOGINDISABLED capability and does NOT permit 1486 the LOGIN command. Server sites SHOULD NOT use any configuration 1487 which permits the LOGIN command without such a protection mechanism 1488 against password snooping. A client implementation MUST NOT send a 1489 LOGIN command if the LOGINDISABLED capability is advertised. 1491 6.3. Client Commands - Authenticated State 1493 In the authenticated state, commands that manipulate mailboxes as 1494 atomic entities are permitted. Of these commands, the SELECT and 1495 EXAMINE commands will select a mailbox for access and enter the 1496 selected state. 1498 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 1499 the following commands are valid in the authenticated state: ENABLE, 1500 SELECT, EXAMINE, NAMESPACE, CREATE, DELETE, RENAME, SUBSCRIBE, 1501 UNSUBSCRIBE, LIST, STATUS, APPEND and IDLE. 1503 6.3.1. ENABLE Command 1505 Arguments: capability names 1507 Responses: no specific responses for this command 1509 Result: OK - Relevant capabilities enabled 1510 BAD - No arguments, or syntax error in an argument 1512 Several IMAP extensions allow the server to return unsolicited 1513 responses specific to these extensions in certain circumstances. 1514 However, servers cannot send those unsolicited responses (with the 1515 exception of response codes (see Section 7.1) included in tagged or 1516 untagged OK/NO/BAD responses, which can always be sent) until they 1517 know that the clients support such extensions and thus won't choke on 1518 the extension response data. 1520 The ENABLE command provides an explicit indication from the client 1521 that it supports particular extensions. It is designed such that the 1522 client can send a simple constant string with the extensions it 1523 supports, and the server will enable the shared subset that both 1524 support. 1526 The ENABLE command takes a list of capability names, and requests the 1527 server to enable the named extensions. Once enabled using ENABLE, 1528 each extension remains active until the IMAP connection is closed. 1529 For each argument, the server does the following: 1531 o If the argument is not an extension known to the server, the 1532 server MUST ignore the argument. 1534 o If the argument is an extension known to the server, and it is not 1535 specifically permitted to be enabled using ENABLE, the server MUST 1536 ignore the argument. (Note that knowing about an extension 1537 doesn't necessarily imply supporting that extension.) 1539 o If the argument is an extension that is supported by the server 1540 and that needs to be enabled, the server MUST enable the extension 1541 for the duration of the connection. Note that once an extension 1542 is enabled, there is no way to disable it. 1544 If the ENABLE command is successful, the server MUST send an untagged 1545 ENABLED response Section 7.2.1. 1547 Clients SHOULD only include extensions that need to be enabled by the 1548 server. For example, a client can enable IMAP4rev2 specific 1549 behaviour when both IMAP4rev1 and IMAP4rev2 are advertised in the 1550 CAPABILITY response. Future RFCs may add to this list. 1552 The ENABLE command is only valid in the authenticated state, before 1553 any mailbox is selected. Clients MUST NOT issue ENABLE once they 1554 SELECT/EXAMINE a mailbox; however, server implementations don't have 1555 to check that no mailbox is selected or was previously selected 1556 during the duration of a connection. 1558 The ENABLE command can be issued multiple times in a session. It is 1559 additive; i.e., "ENABLE a b", followed by "ENABLE c" is the same as a 1560 single command "ENABLE a b c". When multiple ENABLE commands are 1561 issued, each corresponding ENABLED response SHOULD only contain 1562 extensions enabled by the corresponding ENABLE command, i.e. for the 1563 above example, the ENABLED response to "ENABLE c" should not contain 1564 "a" or "b". 1566 There are no limitations on pipelining ENABLE. For example, it is 1567 possible to send ENABLE and then immediately SELECT, or a LOGIN 1568 immediately followed by ENABLE. 1570 The server MUST NOT change the CAPABILITY list as a result of 1571 executing ENABLE; i.e., a CAPABILITY command issued right after an 1572 ENABLE command MUST list the same capabilities as a CAPABILITY 1573 command issued before the ENABLE command. This is demonstrated in 1574 the following example: 1576 C: t1 CAPABILITY 1577 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1578 S: t1 OK foo 1579 C: t2 ENABLE CONDSTORE X-GOOD-IDEA 1580 S: * ENABLED X-GOOD-IDEA 1581 S: t2 OK foo 1582 C: t3 CAPABILITY 1583 S: * CAPABILITY IMAP4rev2 ID LITERAL+ X-GOOD-IDEA 1584 S: t3 OK foo again 1586 In the following example, the client enables CONDSTORE: 1588 C: a1 ENABLE CONDSTORE 1589 S: * ENABLED CONDSTORE 1590 S: a1 OK Conditional Store enabled 1592 6.3.1.1. Note to Designers of Extensions That May Use the ENABLE 1593 Command 1595 Designers of IMAP extensions are discouraged from creating extensions 1596 that require ENABLE unless there is no good alternative design. 1597 Specifically, extensions that cause potentially incompatible behavior 1598 changes to deployed server responses (and thus benefit from ENABLE) 1599 have a higher complexity cost than extensions that do not. 1601 6.3.2. SELECT Command 1603 Arguments: mailbox name 1605 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1606 REQUIRED OK untagged responses: PERMANENTFLAGS, 1607 UIDNEXT, UIDVALIDITY 1608 REQUIRED untagged response: LIST 1610 Result: OK - select completed, now in selected state 1611 NO - select failure, now in authenticated state: no 1612 such mailbox, can't access mailbox 1613 BAD - command unknown or arguments invalid 1615 The SELECT command selects a mailbox so that messages in the mailbox 1616 can be accessed. Before returning an OK to the client, the server 1617 MUST send the following untagged data to the client. (The order of 1618 individual responses is not important.) Note that earlier versions 1619 of this protocol (e.g. IMAP2bis) only required the FLAGS and EXISTS 1620 untagged data; consequently, client implementations SHOULD implement 1621 default behavior for missing data as discussed with the individual 1622 item. 1624 FLAGS Defined flags in the mailbox. See the description of the 1625 FLAGS response for more detail. 1627 EXISTS The number of messages in the mailbox. See the 1628 description of the EXISTS response for more detail. 1630 LIST The server MUST return a LIST response with the mailbox name. 1631 If the server allows de-normalized UTF-8 mailbox names (see 1632 Section 5.1) and the supplied mailbox name differs from the 1633 normalized version, the server MUST return LIST with the OLDNAME 1634 extended data item. See Section 6.3.9.7 for more details. 1636 OK [PERMANENTFLAGS ()] A list of message flags that 1637 the client can change permanently. If this is missing, the client 1638 should assume that all flags can be changed permanently. 1640 OK [UIDNEXT ] The next unique identifier value. Refer to 1641 Section 2.3.1.1 for more information. 1643 OK [UIDVALIDITY ] The unique identifier validity value. Refer to 1644 Section 2.3.1.1 for more information. 1646 Only one mailbox can be selected at a time in a connection; 1647 simultaneous access to multiple mailboxes requires multiple 1648 connections. The SELECT command automatically deselects any 1649 currently selected mailbox before attempting the new selection. 1650 Consequently, if a mailbox is selected and a SELECT command that 1651 fails is attempted, no mailbox is selected. When deselecting a 1652 selected mailbox, the server MUST return an untagged OK response with 1653 the "[CLOSED]" response code when the currently selected mailbox is 1654 closed (see Paragraph 10). 1656 If the client is permitted to modify the mailbox, the server SHOULD 1657 prefix the text of the tagged OK response with the "[READ-WRITE]" 1658 response code. 1660 If the client is not permitted to modify the mailbox but is permitted 1661 read access, the mailbox is selected as read-only, and the server 1662 MUST prefix the text of the tagged OK response to SELECT with the 1663 "[READ-ONLY]" response code. Read-only access through SELECT differs 1664 from the EXAMINE command in that certain read-only mailboxes MAY 1665 permit the change of permanent state on a per-user (as opposed to 1666 global) basis. Netnews messages marked in a server-based .newsrc 1667 file are an example of such per-user permanent state that can be 1668 modified with read-only mailboxes. 1670 Example: C: A142 SELECT INBOX 1671 S: * 172 EXISTS 1672 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1673 S: * OK [UIDNEXT 4392] Predicted next UID 1674 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1675 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1676 S: * LIST () "/" INBOX 1677 S: A142 OK [READ-WRITE] SELECT completed 1679 Example: C: A142 SELECT INBOX 1680 S: * 172 EXISTS 1681 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1682 S: * OK [UIDNEXT 4392] Predicted next UID 1683 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1684 S: * OK [PERMANENTFLAGS (\Deleted \Seen \*)] Limited 1685 S: A142 OK [READ-WRITE] SELECT completed 1686 [...some time later...] 1687 C: A143 SELECT Drafts 1688 S: * OK [CLOSED] Previous mailbox is now closed 1689 S: * 5 EXISTS 1690 S: * OK [UIDVALIDITY 9877410381] UIDs valid 1691 S: * OK [UIDNEXT 102] Predicted next UID 1692 S: * LIST () "/" Drafts 1693 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1694 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Answered 1695 \Flagged \Draft \*)] System flags and keywords allowed 1696 S: A143 OK [READ-WRITE] SELECT completed 1698 Note that IMAP4rev1 compliant servers can also send the untagged 1699 RECENT response which was deprecated in IMAP4rev2. E.g. "* 0 1700 RECENT". Pure IMAP4rev2 clients are advised to ignore the untagged 1701 RECENT response. 1703 6.3.3. EXAMINE Command 1705 Arguments: mailbox name 1707 Responses: REQUIRED untagged responses: FLAGS, EXISTS 1708 REQUIRED OK untagged responses: PERMANENTFLAGS, 1709 UIDNEXT, UIDVALIDITY 1710 REQUIRED untagged response: LIST 1712 Result: OK - examine completed, now in selected state 1713 NO - examine failure, now in authenticated state: no 1714 such mailbox, can't access mailbox BAD - command unknown 1715 or arguments invalid 1717 The EXAMINE command is identical to SELECT and returns the same 1718 output; however, the selected mailbox is identified as read-only. No 1719 changes to the permanent state of the mailbox, including per-user 1720 state, are permitted. 1722 The text of the tagged OK response to the EXAMINE command MUST begin 1723 with the "[READ-ONLY]" response code. 1725 Example: C: A932 EXAMINE blurdybloop 1726 S: * 17 EXISTS 1727 S: * OK [UIDVALIDITY 3857529045] UIDs valid 1728 S: * OK [UIDNEXT 4392] Predicted next UID 1729 S: * LIST () "/" blurdybloop 1730 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 1731 S: * OK [PERMANENTFLAGS ()] No permanent flags permitted 1732 S: A932 OK [READ-ONLY] EXAMINE completed 1734 6.3.4. CREATE Command 1736 Arguments: mailbox name 1738 Responses: OPTIONAL untagged response: LIST 1740 Result: OK - create completed 1741 NO - create failure: can't create mailbox with that name 1742 BAD - command unknown or arguments invalid 1744 The CREATE command creates a mailbox with the given name. An OK 1745 response is returned only if a new mailbox with that name has been 1746 created. It is an error to attempt to create INBOX or a mailbox with 1747 a name that refers to an extant mailbox. Any error in creation will 1748 return a tagged NO response. If a client attempts to create a UTF-8 1749 mailbox name that is not a valid Net-Unicode name, the server MUST 1750 reject the creation or convert the name to Net-Unicode prior to 1751 creating the mailbox. If the server decides to convert (normalize) 1752 the name, it SHOULD return an untagged LIST with OLDNAME extended 1753 data item, with the OLDNAME value being the supplied mailbox name and 1754 the name parameter being the normalized mailbox name. (See 1755 Section 6.3.9.7 for more details.) 1757 Mailboxes created in one IMAP session MAY be announced to other IMAP 1758 sessions using unsolicited LIST response. If the server 1759 automatically subscribes a mailbox when it is created, then the 1760 unsolicited LIST response for each affected subscribed mailbox name 1761 MUST include the \Subscribed attribute. 1763 If the mailbox name is suffixed with the server's hierarchy separator 1764 character (as returned from the server by a LIST command), this is a 1765 declaration that the client intends to create mailbox names under 1766 this name in the hierarchy. Server implementations that do not 1767 require this declaration MUST ignore the declaration. In any case, 1768 the name created is without the trailing hierarchy delimiter. 1770 If the server's hierarchy separator character appears elsewhere in 1771 the name, the server SHOULD create any superior hierarchical names 1772 that are needed for the CREATE command to be successfully completed. 1773 In other words, an attempt to create "foo/bar/zap" on a server in 1774 which "/" is the hierarchy separator character SHOULD create foo/ and 1775 foo/bar/ if they do not already exist. 1777 If a new mailbox is created with the same name as a mailbox which was 1778 deleted, its unique identifiers MUST be greater than any unique 1779 identifiers used in the previous incarnation of the mailbox UNLESS 1780 the new incarnation has a different unique identifier validity value. 1781 See the description of the UID command for more detail. 1783 Example: C: A003 CREATE owatagusiam/ 1784 S: A003 OK CREATE completed 1785 C: A004 CREATE owatagusiam/blurdybloop 1786 S: A004 OK CREATE completed 1787 C: A005 CREATE NonNormalized 1788 S: * LIST () "/" "Normalized" ("OLDNAME" ("NonNormalized")) 1789 S: A005 OK CREATE completed 1791 (in the last example imagine that "NonNormalized" is 1792 a non NFC normalized Unicode mailbox name and that 1793 "Normalized" is its NFC normalized version.) 1795 Note: The interpretation of this example depends on whether "/" 1796 was returned as the hierarchy separator from LIST. If "/" is the 1797 hierarchy separator, a new level of hierarchy named "owatagusiam" 1798 with a member called "blurdybloop" is created. Otherwise, two 1799 mailboxes at the same hierarchy level are created. 1801 6.3.5. DELETE Command 1803 Arguments: mailbox name 1805 Responses: OPTIONAL untagged response: LIST 1807 Result: OK - delete completed 1808 NO - delete failure: can't delete mailbox with that name 1809 BAD - command unknown or arguments invalid 1811 The DELETE command permanently removes the mailbox with the given 1812 name. A tagged OK response is returned only if the mailbox has been 1813 deleted. It is an error to attempt to delete INBOX or a mailbox name 1814 that does not exist. 1816 The DELETE command MUST NOT remove inferior hierarchical names. For 1817 example, if a mailbox "foo" has an inferior "foo.bar" (assuming "." 1818 is the hierarchy delimiter character), removing "foo" MUST NOT remove 1819 "foo.bar". It is an error to attempt to delete a name that has 1820 inferior hierarchical names and also has the \Noselect mailbox name 1821 attribute (see the description of the LIST response for more 1822 details). 1824 It is permitted to delete a name that has inferior hierarchical names 1825 and does not have the \Noselect mailbox name attribute. If the 1826 server implementation does not permit deleting the name while 1827 inferior hierarchical names exists then it SHOULD disallow the DELETE 1828 command by returning a tagged NO response. The NO response SHOULD 1829 include the HASCHILDREN response code. Alternatively the server MAY 1830 allow the DELETE command, but sets the \Noselect mailbox name 1831 attribute for that name. 1833 If the server returns OK response, all messages in that mailbox are 1834 removed by the DELETE command. 1836 The value of the highest-used unique identifier of the deleted 1837 mailbox MUST be preserved so that a new mailbox created with the same 1838 name will not reuse the identifiers of the former incarnation, UNLESS 1839 the new incarnation has a different unique identifier validity value. 1840 See the description of the UID command for more detail. 1842 If the server decides to convert (normalize) the mailbox name, it 1843 SHOULD return an untagged LIST with the "\NonExistent" attribute and 1844 OLDNAME extended data item, with the OLDNAME value being the supplied 1845 mailbox name and the name parameter being the normalized mailbox 1846 name. (See Section 6.3.9.7 for more details.) 1848 Mailboxes deleted in one IMAP session MAY be announced to other IMAP 1849 sessions using unsolicited LIST response, containing the 1850 "\NonExistent" attribute. 1852 Examples: C: A682 LIST "" * 1853 S: * LIST () "/" blurdybloop 1854 S: * LIST (\Noselect) "/" foo 1855 S: * LIST () "/" foo/bar 1856 S: A682 OK LIST completed 1857 C: A683 DELETE blurdybloop 1858 S: A683 OK DELETE completed 1859 C: A684 DELETE foo 1860 S: A684 NO Name "foo" has inferior hierarchical names 1861 C: A685 DELETE foo/bar 1862 S: A685 OK DELETE Completed 1863 C: A686 LIST "" * 1864 S: * LIST (\Noselect) "/" foo 1865 S: A686 OK LIST completed 1866 C: A687 DELETE foo 1867 S: A687 OK DELETE Completed 1868 C: A82 LIST "" * 1869 S: * LIST () "." blurdybloop 1870 S: * LIST () "." foo 1871 S: * LIST () "." foo.bar 1872 S: A82 OK LIST completed 1873 C: A83 DELETE blurdybloop 1874 S: A83 OK DELETE completed 1875 C: A84 DELETE foo 1876 S: A84 OK DELETE Completed 1877 C: A85 LIST "" * 1878 S: * LIST () "." foo.bar 1879 S: A85 OK LIST completed 1880 C: A86 LIST "" % 1881 S: * LIST (\Noselect) "." foo 1882 S: A86 OK LIST completed 1884 6.3.6. RENAME Command 1886 Arguments: existing mailbox name 1887 new mailbox name 1889 Responses: OPTIONAL untagged response: LIST 1891 Result: OK - rename completed 1892 NO - rename failure: can't rename mailbox with that name, 1893 can't rename to mailbox with that name 1894 BAD - command unknown or arguments invalid 1896 The RENAME command changes the name of a mailbox. A tagged OK 1897 response is returned only if the mailbox has been renamed. It is an 1898 error to attempt to rename from a mailbox name that does not exist or 1899 to a mailbox name that already exists. Any error in renaming will 1900 return a tagged NO response. 1902 If the name has inferior hierarchical names, then the inferior 1903 hierarchical names MUST also be renamed. For example, a rename of 1904 "foo" to "zap" will rename "foo/bar" (assuming "/" is the hierarchy 1905 delimiter character) to "zap/bar". 1907 If the server's hierarchy separator character appears in the name, 1908 the server SHOULD create any superior hierarchical names that are 1909 needed for the RENAME command to complete successfully. In other 1910 words, an attempt to rename "foo/bar/zap" to baz/rag/zowie on a 1911 server in which "/" is the hierarchy separator character in the 1912 corresponding namespace SHOULD create baz/ and baz/rag/ if they do 1913 not already exist. 1915 The value of the highest-used unique identifier of the old mailbox 1916 name MUST be preserved so that a new mailbox created with the same 1917 name will not reuse the identifiers of the former incarnation, UNLESS 1918 the new incarnation has a different unique identifier validity value. 1919 See the description of the UID command for more detail. 1921 Renaming INBOX is permitted, and has special behavior. (Note that 1922 some servers disallow renaming INBOX, so clients need to be able to 1923 handle such RENAME failing). It moves all messages in INBOX to a new 1924 mailbox with the given name, leaving INBOX empty. If the server 1925 implementation supports inferior hierarchical names of INBOX, these 1926 are unaffected by a rename of INBOX. 1928 If the server allows creation of mailboxes with names that are not 1929 valid Net-Unicode names, the server normalizes both the existing 1930 mailbox name parameter and the new mailbox name parameter. If the 1931 normalized version of any of these 2 parameters differs from the 1932 corresponding supplied version, the server SHOULD return an untagged 1933 LIST response with OLDNAME extended data item, with the OLDNAME value 1934 being the supplied existing mailbox name and the name parameter being 1935 the normalized new mailbox name (see Section 6.3.9.7). This would 1936 allow the client to correlate supplied name with the normalized name. 1938 Mailboxes renamed in one IMAP session MAY be announced to other IMAP 1939 sessions using unsolicited LIST response with OLDNAME extended data 1940 item. 1942 In both of the above cases: if the server automatically subscribes a 1943 mailbox when it is renamed, then the unsolicited LIST response for 1944 each affected subscribed mailbox name MUST include the \Subscribed 1945 attribute. No unsolicited LIST responses need to be sent for 1946 children mailboxes, if any. When INBOX is successfully renamed, a 1947 new INBOX is assumed to be created. No unsolicited LIST responses 1948 need to be sent for INBOX in this case. 1950 Examples: C: A682 LIST "" * 1951 S: * LIST () "/" blurdybloop 1952 S: * LIST (\Noselect) "/" foo 1953 S: * LIST () "/" foo/bar 1954 S: A682 OK LIST completed 1955 C: A683 RENAME blurdybloop sarasoop 1956 S: A683 OK RENAME completed 1957 C: A684 RENAME foo zowie 1958 S: A684 OK RENAME Completed 1959 C: A685 LIST "" * 1960 S: * LIST () "/" sarasoop 1961 S: * LIST (\Noselect) "/" zowie 1962 S: * LIST () "/" zowie/bar 1963 S: A685 OK LIST completed 1965 C: Z432 LIST "" * 1966 S: * LIST () "." INBOX 1967 S: * LIST () "." INBOX.bar 1968 S: Z432 OK LIST completed 1969 C: Z433 RENAME INBOX old-mail 1970 S: Z433 OK RENAME completed 1971 C: Z434 LIST "" * 1972 S: * LIST () "." INBOX 1973 S: * LIST () "." INBOX.bar 1974 S: * LIST () "." old-mail 1975 S: Z434 OK LIST completed 1977 Note that renaming a mailbox doesn't update subscription information 1978 on the original name. To keep subscription information in sync, the 1979 following sequence of commands can be used: 1981 C: 1001 RENAME X Y 1982 C: 1002 SUBSCRIBE Y 1983 C: 1003 UNSUBSCRIBE X 1985 Note that the above sequence of commands doesn't account for updating 1986 subscription for any children mailboxes of mailbox X. 1988 6.3.7. SUBSCRIBE Command 1990 Arguments: mailbox 1992 Responses: no specific responses for this command 1994 Result: OK - subscribe completed 1995 NO - subscribe failure: can't subscribe to that name 1996 BAD - command unknown or arguments invalid 1998 The SUBSCRIBE command adds the specified mailbox name to the server's 1999 set of "active" or "subscribed" mailboxes as returned by the LIST 2000 (SUBSCRIBED) command. This command returns a tagged OK response if 2001 the subscription is successful or if the mailbox is already 2002 subscribed. 2004 A server MAY validate the mailbox argument to SUBSCRIBE to verify 2005 that it exists. However, it SHOULD NOT unilaterally remove an 2006 existing mailbox name from the subscription list even if a mailbox by 2007 that name no longer exists. 2009 Note: This requirement is because a server site can choose to 2010 routinely remove a mailbox with a well-known name (e.g., "system- 2011 alerts") after its contents expire, with the intention of 2012 recreating it when new contents are appropriate. 2014 Example: C: A002 SUBSCRIBE #news.comp.mail.mime 2015 S: A002 OK SUBSCRIBE completed 2017 6.3.8. UNSUBSCRIBE Command 2019 Arguments: mailbox name 2021 Responses: no specific responses for this command 2023 Result: OK - unsubscribe completed 2024 NO - unsubscribe failure: can't unsubscribe that name 2025 BAD - command unknown or arguments invalid 2027 The UNSUBSCRIBE command removes the specified mailbox name from the 2028 server's set of "active" or "subscribed" mailboxes as returned by the 2029 LIST (SUBSCRIBED) command. This command returns a tagged OK response 2030 if the unsubscription is successful or if the mailbox is not 2031 subscribed. 2033 Example: C: A002 UNSUBSCRIBE #news.comp.mail.mime 2034 S: A002 OK UNSUBSCRIBE completed 2036 6.3.9. LIST Command 2038 Arguments (basic): reference name 2039 mailbox name with possible wildcards 2041 Arguments (extended): selection options (OPTIONAL) 2042 reference name 2043 mailbox patterns 2044 return options (OPTIONAL) 2046 Responses: untagged responses: LIST 2048 Result: OK - list completed 2049 NO - list failure: can't list that reference or name 2050 BAD - command unknown or arguments invalid 2052 The LIST command returns a subset of names from the complete set of 2053 all names available to the client. Zero or more untagged LIST 2054 replies are returned, containing the name attributes, hierarchy 2055 delimiter, name, and possible extension information; see the 2056 description of the LIST reply for more detail. 2058 The LIST command SHOULD return its data quickly, without undue delay. 2059 For example, it SHOULD NOT go to excess trouble to calculate the 2060 \Marked or \Unmarked status or perform other processing; if each name 2061 requires 1 second of processing, then a list of 1200 names would take 2062 20 minutes! 2064 The extended LIST command, originally introduced in [RFC5258], 2065 provides capabilities beyond that of the original IMAP LIST command. 2066 The extended syntax is being used if one or more of the following 2067 conditions is true: 2069 1. if the first word after the command name begins with a 2070 parenthesis ("LIST selection options"); 2072 2. if the second word after the command name begins with a 2073 parenthesis; 2075 3. if the LIST command has more than 2 parameters ("LIST return 2076 options") 2078 An empty ("" string) reference name argument indicates that the 2079 mailbox name is interpreted as by SELECT. The returned mailbox names 2080 MUST match the supplied mailbox name pattern(s). A non-empty 2081 reference name argument is the name of a mailbox or a level of 2082 mailbox hierarchy, and indicates the context in which the mailbox 2083 name is interpreted. Clients SHOULD use the empty reference 2084 argument. 2086 In the basic syntax only, an empty ("" string) mailbox name argument 2087 is a special request to return the hierarchy delimiter and the root 2088 name of the name given in the reference. The value returned as the 2089 root MAY be the empty string if the reference is non-rooted or is an 2090 empty string. In all cases, a hierarchy delimiter (or NIL if there 2091 is no hierarchy) is returned. This permits a client to get the 2092 hierarchy delimiter (or find out that the mailbox names are flat) 2093 even when no mailboxes by that name currently exist. 2095 In the extended syntax, any mailbox name arguments that are empty 2096 strings are ignored. There is no special meaning for empty mailbox 2097 names when the extended syntax is used. 2099 The reference and mailbox name arguments are interpreted into a 2100 canonical form that represents an unambiguous left-to-right 2101 hierarchy. The returned mailbox names will be in the interpreted 2102 form, that we call "canonical LIST pattern" later in this document. 2103 To define the term "canonical LIST pattern" formally: it refers to 2104 the canonical pattern constructed internally by the server from the 2105 reference and mailbox name arguments. 2107 Note: The interpretation of the reference argument is 2108 implementation-defined. It depends upon whether the server 2109 implementation has a concept of the "current working directory" 2110 and leading "break out characters", which override the current 2111 working directory. 2113 For example, on a server which exports a UNIX or NT filesystem, 2114 the reference argument contains the current working directory, and 2115 the mailbox name argument would contain the name as interpreted in 2116 the current working directory. 2118 If a server implementation has no concept of break out characters, 2119 the canonical form is normally the reference name appended with 2120 the mailbox name. Note that if the server implements the 2121 namespace convention (Section 5.1.2.1), "#" is a break out 2122 character and must be treated as such. 2124 If the reference argument is not a level of mailbox hierarchy 2125 (that is, it is a \NoInferiors name), and/or the reference 2126 argument does not end with the hierarchy delimiter, it is 2127 implementation-dependent how this is interpreted. For example, a 2128 reference of "foo/bar" and mailbox name of "rag/baz" could be 2129 interpreted as "foo/bar/rag/baz", "foo/barrag/baz", or "foo/rag/ 2130 baz". A client SHOULD NOT use such a reference argument except at 2131 the explicit request of the user. A hierarchical browser MUST NOT 2132 make any assumptions about server interpretation of the reference 2133 unless the reference is a level of mailbox hierarchy AND ends with 2134 the hierarchy delimiter. 2136 Any part of the reference argument that is included in the 2137 interpreted form SHOULD prefix the interpreted form. It SHOULD also 2138 be in the same form as the reference name argument. This rule 2139 permits the client to determine if the returned mailbox name is in 2140 the context of the reference argument, or if something about the 2141 mailbox argument overrode the reference argument. Without this rule, 2142 the client would have to have knowledge of the server's naming 2143 semantics including what characters are "breakouts" that override a 2144 naming context. 2146 For example, here are some examples of how references 2147 and mailbox names might be interpreted on a UNIX-based 2148 server: 2150 Reference Mailbox Name Interpretation 2151 ------------ ------------ -------------- 2152 ~smith/Mail/ foo.* ~smith/Mail/foo.* 2153 archive/ % archive/% 2154 #news. comp.mail.* #news.comp.mail.* 2155 ~smith/Mail/ /usr/doc/foo /usr/doc/foo 2156 archive/ ~fred/Mail/* ~fred/Mail/* 2158 The first three examples demonstrate interpretations in 2159 the context of the reference argument. Note that 2160 "~smith/Mail" SHOULD NOT be transformed into something 2161 like "/u2/users/smith/Mail", or it would be impossible 2162 for the client to determine that the interpretation was 2163 in the context of the reference. 2165 The character "*" is a wildcard, and matches zero or more characters 2166 at this position. The character "%" is similar to "*", but it does 2167 not match a hierarchy delimiter. If the "%" wildcard is the last 2168 character of a mailbox name argument, matching levels of hierarchy 2169 are also returned. If these levels of hierarchy are not also 2170 selectable mailboxes, they are returned with the \Noselect mailbox 2171 name attribute (see the description of the LIST response for more 2172 details). 2174 Any syntactically valid pattern that is not accepted by a server for 2175 any reason MUST be silently ignored. I.e. it results in no LIST 2176 responses and the LIST command still returns tagged OK response. 2178 Selection options tell the server to limit the mailbox names that are 2179 selected by the LIST operation. If selection options are used, the 2180 mailboxes returned are those that match both the list of canonical 2181 LIST patterns and the selection options. Unless a particular 2182 selection option provides special rules, the selection options are 2183 cumulative: a mailbox that matches the mailbox patterns is selected 2184 only if it also matches all of the selection options. (An example of 2185 a selection option with special rules is the RECURSIVEMATCH option.) 2186 Return options control what information is returned for each matched 2187 mailbox. Return options MUST NOT cause the server to report 2188 information about additional mailbox names other than those that 2189 match the canonical LIST patterns and selection options. If no 2190 return options are specified, the client is only expecting 2191 information about mailbox attributes. The server MAY return other 2192 information about the matched mailboxes, and clients MUST be able to 2193 handle that situation. 2195 Initial selection options and return options are defined in the 2196 following subsections, and new ones will also be defined in 2197 extensions. Initial options defined in this document MUST be 2198 supported. Each non-initial option will be enabled by a capability 2199 string (one capability may enable multiple options), and a client 2200 MUST NOT send an option for which the server has not advertised 2201 support. A server MUST respond to options it does not recognize with 2202 a BAD response. The client SHOULD NOT specify any option more than 2203 once; however, if the client does this, the server MUST act as if it 2204 received the option only once. The order in which options are 2205 specified by the client is not significant. 2207 In general, each selection option except RECURSIVEMATCH will have a 2208 corresponding return option with the same name. The REMOTE selection 2209 option is an anomaly in this regard, and does not have a 2210 corresponding return option. That is because it expands, rather than 2211 restricts, the set of mailboxes that are returned. Future extensions 2212 to this specification should keep this parallelism in mind and define 2213 a pair of corresponding selection and return options. 2215 Server implementations are permitted to "hide" otherwise accessible 2216 mailboxes from the wildcard characters, by preventing certain 2217 characters or names from matching a wildcard in certain situations. 2218 For example, a UNIX-based server might restrict the interpretation of 2219 "*" so that an initial "/" character does not match. 2221 The special name INBOX is included in the output from LIST, if INBOX 2222 is supported by this server for this user and if the uppercase string 2223 "INBOX" matches the interpreted reference and mailbox name arguments 2224 with wildcards as described above. The criteria for omitting INBOX 2225 is whether SELECT INBOX will return failure; it is not relevant 2226 whether the user's real INBOX resides on this or some other server. 2228 6.3.9.1. LIST Selection Options 2230 The selection options defined in this specification are as follows: 2232 SUBSCRIBED - causes the LIST command to list subscribed names, 2233 rather than the existing mailboxes. This will often be a subset 2234 of the actual mailboxes. It's also possible for this list to 2235 contain the names of mailboxes that don't exist. In any case, the 2236 list MUST include exactly those mailbox names that match the 2237 canonical list pattern and are subscribed to. 2239 This option defines a mailbox attribute, "\Subscribed", that 2240 indicates that a mailbox name is subscribed to. The "\Subscribed" 2241 attribute MUST be supported and MUST be accurately computed when 2242 the SUBSCRIBED selection option is specified. 2244 Note that the SUBSCRIBED selection option implies the SUBSCRIBED 2245 return option (see below). 2247 REMOTE - causes the LIST command to show remote mailboxes as well as 2248 local ones, as described in [RFC2193]. This option is intended to 2249 replace the RLIST command and, in conjunction with the SUBSCRIBED 2250 selection option, the RLSUB command. Servers that don't support 2251 remote mailboxes just ignore this option. 2253 This option defines a mailbox attribute, "\Remote", that indicates 2254 that a mailbox is a remote mailbox. The "\Remote" attribute MUST 2255 be accurately computed when the REMOTE option is specified. 2257 The REMOTE selection option has no interaction with other options. 2258 Its effect is to tell the server to apply the other options, if 2259 any, to remote mailboxes, in addition to local ones. In 2260 particular, it has no interaction with RECURSIVEMATCH (see below). 2261 A request for (REMOTE RECURSIVEMATCH) is invalid, because a 2262 request for (RECURSIVEMATCH) is also invalid. A request for 2263 (REMOTE RECURSIVEMATCH SUBSCRIBED) is asking for all subscribed 2264 mailboxes, both local and remote. 2266 RECURSIVEMATCH - this option forces the server to return information 2267 about parent mailboxes that don't match other selection options, 2268 but have some submailboxes that do. Information about children is 2269 returned in the CHILDINFO extended data item, as described in 2270 Section 6.3.9.6. 2272 Note 1: In order for a parent mailbox to be returned, it still has 2273 to match the canonical LIST pattern. 2275 Note 2: When returning the CHILDINFO extended data item, it 2276 doesn't matter whether or not the submailbox matches the canonical 2277 LIST pattern. See also example 9 in Section 6.3.9.8. 2279 The RECURSIVEMATCH option MUST NOT occur as the only selection 2280 option (or only with REMOTE), as it only makes sense when other 2281 selection options are also used. The server MUST return BAD 2282 tagged response in such case. 2284 Note that even if the RECURSIVEMATCH option is specified, the 2285 client MUST still be able to handle a case when a CHILDINFO 2286 extended data item is returned and there are no submailboxes that 2287 meet the selection criteria of the subsequent LIST command, as 2288 they can be deleted/renamed after the LIST response was sent, but 2289 before the client had a chance to access them. 2291 6.3.9.2. LIST Return Options 2293 The return options defined in this specification are as follows: 2295 SUBSCRIBED - causes the LIST command to return subscription state 2296 for all matching mailbox names. The "\Subscribed" attribute MUST 2297 be supported and MUST be accurately computed when the SUBSCRIBED 2298 return option is specified. Further, all mailbox flags MUST be 2299 accurately computed (this differs from the behavior of the 2300 obsolete LSUB command from IMAP4rev1). 2302 CHILDREN - requests mailbox child information as originally proposed 2303 in [RFC3348]. See Section 6.3.9.5, below, for details. This 2304 option MUST be supported by all servers. 2306 STATUS - requests STATUS response for each matching mailbox. 2308 This option takes STATUS data items as parameters. For each 2309 selectable mailbox matching the list pattern and selection 2310 options, the server MUST return an untagged LIST response 2311 followed by an untagged STATUS response containing the 2312 information requested in the STATUS return option, except for 2313 some cases described below. 2315 If an attempted STATUS for a listed mailbox fails because the 2316 mailbox can't be selected (e.g., if the "l" ACL right [RFC4314] 2317 is granted to the mailbox and the "r" right is not granted, or 2318 due to a race condition between LIST and STATUS changing the 2319 mailbox to \NoSelect), the STATUS response MUST NOT be returned 2320 and the LIST response MUST include the \NoSelect attribute. 2321 This means the server may have to buffer the LIST reply until 2322 it has successfully looked up the necessary STATUS information. 2324 If the server runs into unexpected problems while trying to 2325 look up the STATUS information, it MAY drop the corresponding 2326 STATUS reply. In such a situation, the LIST command would 2327 still return a tagged OK reply. 2329 6.3.9.3. General Principles for Returning LIST Responses 2331 This section outlines several principles that can be used by server 2332 implementations of this document to decide whether a LIST response 2333 should be returned, as well as how many responses and what kind of 2334 information they may contain. 2336 1. At most one LIST response should be returned for each mailbox 2337 name that matches the canonical LIST pattern. Server 2338 implementors must not assume that clients will be able to 2339 assemble mailbox attributes and other information returned in 2340 multiple LIST responses. 2342 2. There are only two reasons for including a matching mailbox name 2343 in the responses to the LIST command (note that the server is 2344 allowed to return unsolicited responses at any time, and such 2345 responses are not governed by this rule): 2347 A. The mailbox name also satisfies the selection criteria. 2349 B. The mailbox name doesn't satisfy the selection criteria, but 2350 it has at least one descendant mailbox name that satisfies 2351 the selection criteria and that doesn't match the canonical 2352 LIST pattern. 2354 For more information on this case, see the CHILDINFO extended 2355 data item described in Section 6.3.9.6. Note that the 2356 CHILDINFO extended data item can only be returned when the 2357 RECURSIVEMATCH selection option is specified. 2359 3. Attributes returned in the same LIST response must be treated 2360 additively. For example, the following response 2362 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2364 means that the "Fruit/Peach" mailbox doesn't exist, but it is 2365 subscribed. 2367 6.3.9.4. Additional LIST-related Requirements on Clients 2369 All clients MUST treat a LIST attribute with a stronger meaning as 2370 implying any attribute that can be inferred from it. (See 2371 Section 7.2.3 for the list of currently defined attributes). For 2372 example, the client must treat the presence of the \NoInferiors 2373 attribute as if the \HasNoChildren attribute was also sent by the 2374 server. 2376 The following table summarizes inference rules. 2378 +--------------------+-------------------+ 2379 | returned attribute | implied attribute | 2380 +--------------------+-------------------+ 2381 | \NoInferiors | \HasNoChildren | 2382 | \NonExistent | \NoSelect | 2383 +--------------------+-------------------+ 2385 6.3.9.5. The CHILDREN Return Option 2387 The CHILDREN return option is simply an indication that the client 2388 wants information about whether or not mailboxes contain children 2389 mailboxes; a server MAY provide it even if the option is not 2390 specified. 2392 Many IMAP4 clients present to the user a hierarchical view of the 2393 mailboxes that a user has access to. Rather than initially 2394 presenting to the user the entire mailbox hierarchy, it is often 2395 preferable to show to the user a collapsed outline list of the 2396 mailbox hierarchy (particularly if there is a large number of 2397 mailboxes). The user can then expand the collapsed outline hierarchy 2398 as needed. It is common to include within the collapsed hierarchy a 2399 visual clue (such as a ''+'') to indicate that there are child 2400 mailboxes under a particular mailbox. When the visual clue is 2401 clicked, the hierarchy list is expanded to show the child mailboxes. 2402 The CHILDREN return option provides a mechanism for a client to 2403 efficiently determine whether a particular mailbox has children, 2404 without issuing a LIST "" * or a LIST "" % for each mailbox name. 2405 The CHILDREN return option defines two new attributes that MUST be 2406 returned within a LIST response: \HasChildren and \HasNoChildren. 2407 Although these attributes MAY be returned in response to any LIST 2408 command, the CHILDREN return option is provided to indicate that the 2409 client particularly wants this information. If the CHILDREN return 2410 option is present, the server MUST return these attributes even if 2411 their computation is expensive. 2413 \HasChildren 2415 The presence of this attribute indicates that the mailbox has 2416 child mailboxes. A server SHOULD NOT set this attribute if 2417 there are child mailboxes and the user does not have permission 2418 to access any of them. In this case, \HasNoChildren SHOULD be 2419 used. In many cases, however, a server may not be able to 2420 efficiently compute whether a user has access to any child 2421 mailbox. Note that even though the \HasChildren attribute for a 2422 mailbox must be correct at the time of processing of the 2423 mailbox, a client must be prepared to deal with a situation when 2424 a mailbox is marked with the \HasChildren attribute, but no 2425 child mailbox appears in the response to the LIST command. This 2426 might happen, for example, due to children mailboxes being 2427 deleted or made inaccessible to the user (using access control) 2428 by another client before the server is able to list them. 2430 \HasNoChildren 2432 The presence of this attribute indicates that the mailbox has NO 2433 child mailboxes that are accessible to the currently 2434 authenticated user. 2436 It is an error for the server to return both a \HasChildren and a 2437 \HasNoChildren attribute in the same LIST response. 2439 Note: the \HasNoChildren attribute should not be confused with the 2440 the \NoInferiors attribute, which indicates that no child mailboxes 2441 exist now and none can be created in the future. 2443 6.3.9.6. CHILDINFO Extended Data Item 2445 The CHILDINFO extended data item MUST NOT be returned unless the 2446 client has specified the RECURSIVEMATCH selection option. 2448 The CHILDINFO extended data item in a LIST response describes the 2449 selection criteria that has caused it to be returned and indicates 2450 that the mailbox has at least one descendant mailbox that matches the 2451 selection criteria. 2453 Note: Some servers allow for mailboxes to exist without requiring 2454 their parent to exist. For example, a mailbox "Customers/ABC" can 2455 exist while the mailbox "Customers" does not. As CHILDINFO extended 2456 data item is not allowed if the RECURSIVEMATCH selection option is 2457 not specified, such servers SHOULD use the "\NonExistent 2458 \HasChildren" attribute pair to signal to the client that there is a 2459 descendant mailbox that matches the selection criteria. See example 2460 11 in Section 6.3.9.8. 2462 The returned selection criteria allow the client to distinguish a 2463 solicited response from an unsolicited one, as well as to distinguish 2464 among solicited responses caused by multiple pipelined LIST commands 2465 that specify different criteria. 2467 Servers SHOULD ONLY return a non-matching mailbox name along with 2468 CHILDINFO if at least one matching child is not also being returned. 2469 That is, servers SHOULD suppress redundant CHILDINFO responses. 2471 Examples 8 and 10 in Section 6.3.9.8 demonstrate the difference 2472 between present CHILDINFO extended data item and the "\HasChildren" 2473 attribute. 2475 The following table summarizes interaction between the "\NonExistent" 2476 attribute and CHILDINFO (the first column indicates whether the 2477 parent mailbox exists): 2479 +--------+-------------+------------------+-------------------------+ 2480 | exists | meets the | has a child that | returned | 2481 | | selection | meets the | IMAP4rev2/LIST-EXTENDED | 2482 | | criteria | selection | attributes and | 2483 | | | criteria | CHILDINFO | 2484 +--------+-------------+------------------+-------------------------+ 2485 | no | no | no | no LIST response | 2486 | | | | returned | 2487 | yes | no | no | no LIST response | 2488 | | | | returned | 2489 | no | yes | no | (\NonExistent ) | 2490 | yes | yes | no | () | 2491 | no | no | yes | (\NonExistent) + | 2492 | | | | CHILDINFO | 2493 | yes | no | yes | () + CHILDINFO | 2494 | no | yes | yes | (\NonExistent ) + | 2495 | | | | CHILDINFO | 2496 | yes | yes | yes | () + CHILDINFO | 2497 +--------+-------------+------------------+-------------------------+ 2499 where is one or more attributes that correspond to the 2500 selection criteria; for example, for the SUBSCRIBED option the 2501 is \Subscribed. 2503 6.3.9.7. OLDNAME Extended Data Item 2505 The OLDNAME extended data item is included when a mailbox name is 2506 created (with CREATE command), renamed (with RENAME command) or 2507 deleted (with DELETE command). (When a mailbox is deleted the 2508 "\NonExistent" attribute is also included.) IMAP extensions can 2509 specify other conditions when OLDNAME extended data item should be 2510 included. 2512 If the server allows de-normalized mailbox names (see Section 5.1) in 2513 SELECT/EXAMINE, CREATE, RENAME or DELETE, it SHOULD return an 2514 unsolicited LIST response that includes OLDNAME extended data item, 2515 whenever the supplied mailbox name differs from the resulting 2516 normalized mailbox name. From the client point of view this is 2517 indistinguishable from another user renaming of deleting the mailbox, 2518 as specified in the previous paragraph. 2520 A deleted mailbox can be announced like this: 2522 S: * LIST (\NonExistent) "." "INBOX.DeletedMailbox" 2524 Example of a renamed mailbox: 2526 S: * LIST () "/" "NewMailbox" ("OLDNAME" ("OldMailbox")) 2528 6.3.9.8. LIST Command Examples 2530 This example shows some uses of the basic LIST command: 2532 Example: C: A101 LIST "" "" 2533 S: * LIST (\Noselect) "/" "" 2534 S: A101 OK LIST Completed 2535 C: A102 LIST #news.comp.mail.misc "" 2536 S: * LIST (\Noselect) "." #news. 2537 S: A102 OK LIST Completed 2538 C: A103 LIST /usr/staff/jones "" 2539 S: * LIST (\Noselect) "/" / 2540 S: A103 OK LIST Completed 2541 C: A202 LIST ~/Mail/ % 2542 S: * LIST (\Noselect) "/" ~/Mail/foo 2543 S: * LIST () "/" ~/Mail/meetings 2544 S: A202 OK LIST completed 2546 Extended examples: 2548 1: The first example shows the complete local hierarchy that will 2549 be used for the other examples. 2551 C: A01 LIST "" "*" 2552 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2553 S: * LIST () "/" "Fruit" 2554 S: * LIST () "/" "Fruit/Apple" 2555 S: * LIST () "/" "Fruit/Banana" 2556 S: * LIST () "/" "Tofu" 2557 S: * LIST () "/" "Vegetable" 2558 S: * LIST () "/" "Vegetable/Broccoli" 2559 S: * LIST () "/" "Vegetable/Corn" 2560 S: A01 OK done 2562 2: In the next example, we will see the subscribed mailboxes. This 2563 is similar to, but not equivalent with now deprecated, (see [RFC3501] for more details on LSUB command). Note 2565 that the mailbox called "Fruit/Peach" is subscribed to, but does 2566 not actually exist (perhaps it was deleted while still 2567 subscribed). The "Fruit" mailbox is not subscribed to, but it 2568 has two subscribed children. The "Vegetable" mailbox is 2569 subscribed and has two children; one of them is subscribed as 2570 well. 2572 C: A02 LIST (SUBSCRIBED) "" "*" 2573 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2574 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2575 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2576 S: * LIST (\Subscribed) "/" "Vegetable" 2577 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2578 S: A02 OK done 2580 3: The next example shows the use of the CHILDREN option. The 2581 client, without having to list the second level of hierarchy, 2582 now knows which of the top-level mailboxes have submailboxes 2583 (children) and which do not. Note that it's not necessary for 2584 the server to return the \HasNoChildren attribute for the inbox, 2585 because the \NoInferiors attribute already implies that, and has 2586 a stronger meaning. 2588 C: A03 LIST () "" "%" RETURN (CHILDREN) 2589 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2590 S: * LIST (\HasChildren) "/" "Fruit" 2591 S: * LIST (\HasNoChildren) "/" "Tofu" 2592 S: * LIST (\HasChildren) "/" "Vegetable" 2593 S: A03 OK done 2595 4: In this example, we see more mailboxes that reside on another 2596 server. This is similar to the command . 2598 C: A04 LIST (REMOTE) "" "%" RETURN (CHILDREN) 2599 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2600 S: * LIST (\HasChildren) "/" "Fruit" 2601 S: * LIST (\HasNoChildren) "/" "Tofu" 2602 S: * LIST (\HasChildren) "/" "Vegetable" 2603 S: * LIST (\Remote) "/" "Bread" 2604 S: * LIST (\HasChildren \Remote) "/" "Meat" 2605 S: A04 OK done 2607 5: The following example also requests the server to include 2608 mailboxes that reside on another server. The server returns 2609 information about all mailboxes that are subscribed. This is 2610 similar to the command (see [RFC2193] for more 2611 details on RLSUB). We also see the use of two selection 2612 options. 2614 C: A05 LIST (REMOTE SUBSCRIBED) "" "*" 2615 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2616 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2617 S: * LIST (\Subscribed \NonExistent) "/" "Fruit/Peach" 2618 S: * LIST (\Subscribed) "/" "Vegetable" 2619 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2620 S: * LIST (\Remote \Subscribed) "/" "Bread" 2621 S: A05 OK done 2623 6: The following example requests the server to include mailboxes 2624 that reside on another server. The server is asked to return 2625 subscription information for all returned mailboxes. This is 2626 different from the example above. 2628 Note that the output of this command is not a superset of the 2629 output in the previous example, as it doesn't include LIST 2630 response for the non-existent "Fruit/Peach". 2632 C: A06 LIST (REMOTE) "" "*" RETURN (SUBSCRIBED) 2633 S: * LIST (\Marked \NoInferiors \Subscribed) "/" "inbox" 2634 S: * LIST () "/" "Fruit" 2635 S: * LIST () "/" "Fruit/Apple" 2636 S: * LIST (\Subscribed) "/" "Fruit/Banana" 2637 S: * LIST () "/" "Tofu" 2638 S: * LIST (\Subscribed) "/" "Vegetable" 2639 S: * LIST (\Subscribed) "/" "Vegetable/Broccoli" 2640 S: * LIST () "/" "Vegetable/Corn" 2641 S: * LIST (\Remote \Subscribed) "/" "Bread" 2642 S: * LIST (\Remote) "/" "Meat" 2643 S: A06 OK done 2645 7: The following example demonstrates the difference between the 2646 \HasChildren attribute and the CHILDINFO extended data item. 2648 Let's assume there is the following hierarchy: 2650 C: C01 LIST "" "*" 2651 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2652 S: * LIST () "/" "Foo" 2653 S: * LIST () "/" "Foo/Bar" 2654 S: * LIST () "/" "Foo/Baz" 2655 S: * LIST () "/" "Moo" 2656 S: C01 OK done 2658 If the client asks RETURN (CHILDREN), it will get this: 2660 C: CA3 LIST "" "%" RETURN (CHILDREN) 2661 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2662 S: * LIST (\HasChildren) "/" "Foo" 2663 S: * LIST (\HasNoChildren) "/" "Moo" 2664 S: CA3 OK done 2666 A) Let's also assume that the mailbox "Foo/Baz" is the only 2667 subscribed mailbox. Then we get this result: 2669 C: C02 LIST (SUBSCRIBED) "" "*" 2670 S: * LIST (\Subscribed) "/" "Foo/Baz" 2671 S: C02 OK done 2673 Now, if the client issues , the server 2674 will return no mailboxes (as the mailboxes "Moo", "Foo", and 2675 "Inbox" are NOT subscribed). However, if the client issues 2676 this: 2678 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2679 S: * LIST () "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2680 S: C04 OK done 2682 (i.e., the mailbox "Foo" is not subscribed, but it has a child 2683 that is.) 2685 A1) If the mailbox "Foo" had also been subscribed, the last 2686 command would return this: 2688 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2689 S: * LIST (\Subscribed) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2690 S: C04 OK done 2692 or even this: 2694 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2695 S: * LIST (\Subscribed \HasChildren) "/" "Foo" ("CHILDINFO" 2696 ("SUBSCRIBED")) 2697 S: C04 OK done 2699 A2) If we assume instead that the mailbox "Foo" is not part of 2700 the original hierarchy and is not subscribed, the last command 2701 will give this result: 2703 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" 2704 S: * LIST (\NonExistent) "/" "Foo" ("CHILDINFO" ("SUBSCRIBED")) 2705 S: C04 OK done 2706 B) Now, let's assume that no mailbox is subscribed. In this 2707 case, the command will 2708 return no responses, as there are no subscribed children (even 2709 though "Foo" has children). 2711 C) And finally, suppose that only the mailboxes "Foo" and "Moo" 2712 are subscribed. In that case, we see this result: 2714 C: C04 LIST (SUBSCRIBED RECURSIVEMATCH) "" "%" RETURN (CHILDREN) 2715 S: * LIST (\HasChildren \Subscribed) "/" "Foo" 2716 S: * LIST (\HasNoChildren \Subscribed) "/" "Moo" 2717 S: C04 OK done 2719 (which means that the mailbox "Foo" has children, but none of 2720 them is subscribed). 2722 8: The following example demonstrates that the CHILDINFO extended 2723 data item is returned whether or not children mailboxes match 2724 the canonical LIST pattern. 2726 Let's assume there is the following hierarchy: 2728 C: D01 LIST "" "*" 2729 S: * LIST (\Marked \NoInferiors) "/" "inbox" 2730 S: * LIST () "/" "foo2" 2731 S: * LIST () "/" "foo2/bar1" 2732 S: * LIST () "/" "foo2/bar2" 2733 S: * LIST () "/" "baz2" 2734 S: * LIST () "/" "baz2/bar2" 2735 S: * LIST () "/" "baz2/bar22" 2736 S: * LIST () "/" "baz2/bar222" 2737 S: * LIST () "/" "eps2" 2738 S: * LIST () "/" "eps2/mamba" 2739 S: * LIST () "/" "qux2/bar2" 2740 S: D01 OK done 2742 And that the following mailboxes are subscribed: 2744 C: D02 LIST (SUBSCRIBED) "" "*" 2745 S: * LIST (\Subscribed) "/" "foo2/bar1" 2746 S: * LIST (\Subscribed) "/" "foo2/bar2" 2747 S: * LIST (\Subscribed) "/" "baz2/bar2" 2748 S: * LIST (\Subscribed) "/" "baz2/bar22" 2749 S: * LIST (\Subscribed) "/" "baz2/bar222" 2750 S: * LIST (\Subscribed) "/" "eps2" 2751 S: * LIST (\Subscribed) "/" "eps2/mamba" 2752 S: * LIST (\Subscribed) "/" "qux2/bar2" 2753 S: D02 OK done 2754 The client issues the following command first: 2756 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*2" 2757 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2758 S: * LIST (\Subscribed) "/" "foo2/bar2" 2759 S: * LIST (\Subscribed) "/" "baz2/bar2" 2760 S: * LIST (\Subscribed) "/" "baz2/bar22" 2761 S: * LIST (\Subscribed) "/" "baz2/bar222" 2762 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2763 S: * LIST (\Subscribed) "/" "qux2/bar2" 2764 S: D03 OK done 2766 and the server may also include (but this would violate a SHOULD 2767 NOT in Section 3.5, because CHILDINFO is redundant) 2769 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2770 S: * LIST (\NonExistent) "/" "qux2" ("CHILDINFO" ("SUBSCRIBED")) 2772 The CHILDINFO extended data item is returned for mailboxes 2773 "foo2", "baz2", and "eps2", because all of them have subscribed 2774 children, even though for the mailbox "foo2" only one of the two 2775 subscribed children matches the pattern, for the mailbox "baz2" 2776 all the subscribed children match the pattern, and for the 2777 mailbox "eps2" none of the subscribed children matches the 2778 pattern. 2780 Note that if the client issues 2782 C: D03 LIST (RECURSIVEMATCH SUBSCRIBED) "" "*" 2783 S: * LIST () "/" "foo2" ("CHILDINFO" ("SUBSCRIBED")) 2784 S: * LIST (\Subscribed) "/" "foo2/bar1" 2785 S: * LIST (\Subscribed) "/" "foo2/bar2" 2786 S: * LIST () "/" "baz2" ("CHILDINFO" ("SUBSCRIBED")) 2787 S: * LIST (\Subscribed) "/" "baz2/bar2" 2788 S: * LIST (\Subscribed) "/" "baz2/bar22" 2789 S: * LIST (\Subscribed) "/" "baz2/bar222" 2790 S: * LIST (\Subscribed) "/" "eps2" ("CHILDINFO" ("SUBSCRIBED")) 2791 S: * LIST (\Subscribed) "/" "eps2/mamba" 2792 S: * LIST (\Subscribed) "/" "qux2/bar2" 2793 S: D03 OK done 2795 The LIST responses for mailboxes "foo2", "baz2", and "eps2" 2796 still have the CHILDINFO extended data item, even though this 2797 information is redundant and the client can determine it by 2798 itself. 2800 9: The following example shows usage of extended syntax for mailbox 2801 pattern. It also demonstrates that the presence of the 2802 CHILDINFO extended data item doesn't necessarily imply 2803 \HasChildren. 2805 C: a1 LIST "" ("foo") 2806 S: * LIST () "/" foo 2807 S: a1 OK done 2809 C: a2 LIST (SUBSCRIBED) "" "foo/*" 2810 S: * LIST (\Subscribed \NonExistent) "/" foo/bar 2811 S: a2 OK done 2813 C: a3 LIST (SUBSCRIBED RECURSIVEMATCH) "" foo RETURN (CHILDREN) 2814 S: * LIST (\HasNoChildren) "/" foo ("CHILDINFO" ("SUBSCRIBED")) 2815 S: a3 OK done 2817 10: The following example shows how a server that supports missing 2818 mailbox hierarchy elements can signal to a client that didn't 2819 specify the RECURSIVEMATCH selection option that there is a 2820 child mailbox that matches the selection criteria. 2822 C: a1 LIST (REMOTE) "" * 2823 S: * LIST () "/" music/rock 2824 S: * LIST (\Remote) "/" also/jazz 2825 S: a1 OK done 2827 C: a2 LIST () "" % 2828 S: * LIST (\NonExistent \HasChildren) "/" music 2829 S: a2 OK done 2831 C: a3 LIST (REMOTE) "" % 2832 S: * LIST (\NonExistent \HasChildren) "/" music 2833 S: * LIST (\NonExistent \HasChildren) "/" also 2834 S: a3 OK done 2836 C: a3.1 LIST "" (% music/rock) 2837 S: * LIST () "/" music/rock 2838 S: a3.1 OK done 2840 Because "music/rock" is the only mailbox under "music", there's 2841 no need for the server to also return "music". However clients 2842 must handle both cases. 2844 11: The following examples show use of STATUS return option. 2846 C: A01 LIST "" % RETURN (STATUS (MESSAGES UNSEEN)) 2847 S: * LIST () "." "INBOX" 2848 S: * STATUS "INBOX" (MESSAGES 17 UNSEEN 16) 2849 S: * LIST () "." "foo" 2850 S: * STATUS "foo" (MESSAGES 30 UNSEEN 29) 2851 S: * LIST (\NoSelect) "." "bar" 2852 S: A01 OK List completed. 2854 The "bar" mailbox isn't selectable, so it has no STATUS reply. 2856 C: A02 LIST (SUBSCRIBED RECURSIVEMATCH) "" % RETURN (STATUS 2857 (MESSAGES)) 2858 S: * LIST (\Subscribed) "." "INBOX" 2859 S: * STATUS "INBOX" (MESSAGES 17) 2860 S: * LIST () "." "foo" (CHILDINFO ("SUBSCRIBED")) 2861 S: A02 OK List completed. 2863 The LIST reply for "foo" is returned because it has matching 2864 children, but no STATUS reply is returned because "foo" itself 2865 doesn't match the selection criteria. 2867 6.3.10. NAMESPACE Command 2869 Arguments: none 2871 Responses: REQUIRED untagged responses: NAMESPACE 2873 Result: OK - command completed 2874 NO - Can't complete the command 2875 BAD - arguments invalid 2877 The NAMESPACE command causes a single ungagged NAMESPACE response to 2878 be returned. The untagged NAMESPACE response contains the prefix and 2879 hierarchy delimiter to the server's Personal Namespace(s), Other 2880 Users' Namespace(s), and Shared Namespace(s) that the server wishes 2881 to expose. The response will contain a NIL for any namespace class 2882 that is not available. The Namespace-Response-Extensions ABNF non 2883 terminal is defined for extensibility and MAY be included in the 2884 NAMESPACE response. 2886 Example 1: 2888 In this example a server supports a single personal namespace. No 2889 leading prefix is used on personal mailboxes and "/" is the hierarchy 2890 delimiter. 2892 C: A001 NAMESPACE 2893 S: * NAMESPACE (("" "/")) NIL NIL 2894 S: A001 OK NAMESPACE command completed 2896 Example 2: 2898 A user logged on anonymously to a server. No personal mailboxes are 2899 associated with the anonymous user and the user does not have access 2900 to the Other Users' Namespace. No prefix is required to access 2901 shared mailboxes and the hierarchy delimiter is "." 2903 C: A001 NAMESPACE 2904 S: * NAMESPACE NIL NIL (("" ".")) 2905 S: A001 OK NAMESPACE command completed 2907 Example 3: 2909 A server that contains a Personal Namespace and a single Shared 2910 Namespace. 2912 C: A001 NAMESPACE 2913 S: * NAMESPACE (("" "/")) NIL (("Public Folders/" "/")) 2914 S: A001 OK NAMESPACE command completed 2916 Example 4: 2918 A server that contains a Personal Namespace, Other Users' Namespace 2919 and multiple Shared Namespaces. Note that the hierarchy delimiter 2920 used within each namespace can be different. 2922 C: A001 NAMESPACE 2923 S: * NAMESPACE (("" "/")) (("~" "/")) (("#shared/" "/") 2924 ("#public/" "/")("#ftp/" "/")("#news." ".")) 2925 S: A001 OK NAMESPACE command completed 2927 The prefix string allows a client to do things such as automatically 2928 creating personal mailboxes or LISTing all available mailboxes within 2929 a namespace. 2931 Example 5: 2933 A server that supports only the Personal Namespace, with a leading 2934 prefix of INBOX to personal mailboxes and a hierarchy delimiter of 2935 "." 2936 C: A001 NAMESPACE 2937 S: * NAMESPACE (("INBOX." ".")) NIL NIL 2938 S: A001 OK NAMESPACE command completed 2940 < Automatically create a mailbox to store sent items.> 2942 C: A002 CREATE "INBOX.Sent Mail" 2943 S: A002 OK CREATE command completed 2945 Although typically a server will support only a single Personal 2946 Namespace, and a single Other User's Namespace, circumstances exist 2947 where there MAY be multiples of these, and a client MUST be prepared 2948 for them. If a client is configured such that it is required to 2949 create a certain mailbox, there can be circumstances where it is 2950 unclear which Personal Namespaces it should create the mailbox in. 2951 In these situations a client SHOULD let the user select which 2952 namespaces to create the mailbox in or just use the first personal 2953 namespace. 2955 Example 6: 2957 In this example, a server supports 2 Personal Namespaces. In 2958 addition to the regular Personal Namespace, the user has an 2959 additional personal namespace to allow access to mailboxes in an MH 2960 format mailstore. 2962 The client is configured to save a copy of all mail sent by the user 2963 into a mailbox called 'Sent Mail'. Furthermore, after a message is 2964 deleted from a mailbox, the client is configured to move that message 2965 to a mailbox called 'Deleted Items'. 2967 Note that this example demonstrates how some extension flags can be 2968 passed to further describe the #mh namespace. 2970 C: A001 NAMESPACE 2971 S: * NAMESPACE (("" "/")("#mh/" "/" "X-PARAM" 2972 ("FLAG1" "FLAG2"))) NIL NIL 2973 S: A001 OK NAMESPACE command completed 2975 < It is desired to keep only one copy of sent mail. 2976 It is unclear which Personal Namespace the client 2977 should use to create the 'Sent Mail' mailbox. 2978 The user is prompted to select a namespace and only 2979 one 'Sent Mail' mailbox is created. > 2981 C: A002 CREATE "Sent Mail" 2982 S: A002 OK CREATE command completed 2984 < The client is designed so that it keeps two 2985 'Deleted Items' mailboxes, one for each namespace. > 2987 C: A003 CREATE "Delete Items" 2988 S: A003 OK CREATE command completed 2990 C: A004 CREATE "#mh/Deleted Items" 2991 S: A004 OK CREATE command completed 2993 The next level of hierarchy following the Other Users' Namespace 2994 prefix SHOULD consist of , where is a user name 2995 as per the LOGIN or AUTHENTICATE command. 2997 A client can construct a LIST command by appending a "%" to the Other 2998 Users' Namespace prefix to discover the Personal Namespaces of other 2999 users that are available to the currently authenticated user. 3001 In response to such a LIST command, a server SHOULD NOT return user 3002 names that have not granted access to their personal mailboxes to the 3003 user in question. 3005 A server MAY return a LIST response containing only the names of 3006 users that have explicitly granted access to the user in question. 3008 Alternatively, a server MAY return NO to such a LIST command, 3009 requiring that a user name be included with the Other Users' 3010 Namespace prefix before listing any other user's mailboxes. 3012 Example 7: 3014 A server that supports providing a list of other user's mailboxes 3015 that are accessible to the currently logged on user. 3017 C: A001 NAMESPACE 3018 S: * NAMESPACE (("" "/")) (("Other Users/" "/")) NIL 3019 S: A001 OK NAMESPACE command completed 3021 C: A002 LIST "" "Other Users/%" 3022 S: * LIST () "/" "Other Users/Mike" 3023 S: * LIST () "/" "Other Users/Karen" 3024 S: * LIST () "/" "Other Users/Matthew" 3025 S: * LIST () "/" "Other Users/Tesa" 3026 S: A002 OK LIST command completed 3028 Example 8: 3030 A server that does not support providing a list of other user's 3031 mailboxes that are accessible to the currently logged on user. The 3032 mailboxes are listable if the client includes the name of the other 3033 user with the Other Users' Namespace prefix. 3035 C: A001 NAMESPACE 3036 S: * NAMESPACE (("" "/")) (("#Users/" "/")) NIL 3037 S: A001 OK NAMESPACE command completed 3039 < In this example, the currently logged on user has access to 3040 the Personal Namespace of user Mike, but the server chose to 3041 suppress this information in the LIST response. However, 3042 by appending the user name Mike (received through user input) 3043 to the Other Users' Namespace prefix, the client is able 3044 to get a listing of the personal mailboxes of user Mike. > 3046 C: A002 LIST "" "#Users/%" 3047 S: A002 NO The requested item could not be found. 3049 C: A003 LIST "" "#Users/Mike/%" 3050 S: * LIST () "/" "#Users/Mike/INBOX" 3051 S: * LIST () "/" "#Users/Mike/Foo" 3052 S: A003 OK LIST command completed. 3054 A prefix string might not contain a hierarchy delimiter, because in 3055 some cases it is not needed as part of the prefix. 3057 Example 9: 3059 A server that allows access to the Other Users' Namespace by 3060 prefixing the others' mailboxes with a '~' followed by , 3061 where is a user name as per the LOGIN or AUTHENTICATE 3062 command. 3064 C: A001 NAMESPACE 3065 S: * NAMESPACE (("" "/")) (("~" "/")) NIL 3066 S: A001 OK NAMESPACE command completed 3068 < List the mailboxes for user mark > 3070 C: A002 LIST "" "~mark/%" 3071 S: * LIST () "/" "~mark/INBOX" 3072 S: * LIST () "/" "~mark/foo" 3073 S: A002 OK LIST command completed 3075 6.3.11. STATUS Command 3077 Arguments: mailbox name 3078 status data item names 3080 Responses: REQUIRED untagged responses: STATUS 3082 Result: OK - status completed 3083 NO - status failure: no status for that name 3084 BAD - command unknown or arguments invalid 3086 The STATUS command requests the status of the indicated mailbox. It 3087 does not change the currently selected mailbox, nor does it affect 3088 the state of any messages in the queried mailbox. 3090 The STATUS command provides an alternative to opening a second 3091 IMAP4rev2 connection and doing an EXAMINE command on a mailbox to 3092 query that mailbox's status without deselecting the current mailbox 3093 in the first IMAP4rev2 connection. 3095 Unlike the LIST command, the STATUS command is not guaranteed to be 3096 fast in its response. Under certain circumstances, it can be quite 3097 slow. In some implementations, the server is obliged to open the 3098 mailbox read-only internally to obtain certain status information. 3099 Also unlike the LIST command, the STATUS command does not accept 3100 wildcards. 3102 Note: The STATUS command is intended to access the status of 3103 mailboxes other than the currently selected mailbox. Because the 3104 STATUS command can cause the mailbox to be opened internally, and 3105 because this information is available by other means on the 3106 selected mailbox, the STATUS command SHOULD NOT be used on the 3107 currently selected mailbox. However, servers MUST be able to 3108 execute STATUS command on the selected mailbox. (This might also 3109 implicitly happen when STATUS return option is used in a LIST 3110 command). 3112 The STATUS command MUST NOT be used as a "check for new messages 3113 in the selected mailbox" operation (refer to sections Section 7, 3114 Section 7.3.1 for more information about the proper method for new 3115 message checking). 3117 STATUS SIZE (see below) can take a significant amount of time, 3118 depending upon server implementation. Clients should use STATUS 3119 SIZE cautiously. 3121 The currently defined status data items that can be requested are: 3123 MESSAGES The number of messages in the mailbox. 3125 UIDNEXT The next unique identifier value of the mailbox. Refer to 3126 Section 2.3.1.1 for more information. 3128 UIDVALIDITY The unique identifier validity value of the mailbox. 3129 Refer to Section 2.3.1.1 for more information. 3131 UNSEEN The number of messages which do not have the \Seen flag set. 3133 DELETED The number of messages which have the \Deleted flag set. 3135 SIZE The total size of the mailbox in octets. This is not strictly 3136 required to be an exact value, but it MUST be equal to or greater 3137 than the sum of the values of the RFC822.SIZE FETCH message data 3138 items (see Section 6.4.5) of all messages in the mailbox. 3140 Example: C: A042 STATUS blurdybloop (UIDNEXT MESSAGES) 3141 S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 3142 S: A042 OK STATUS completed 3144 6.3.12. APPEND Command 3146 Arguments: mailbox name 3147 OPTIONAL flag parenthesized list 3148 OPTIONAL date/time string 3149 message literal 3151 Responses: OPTIONAL untagged response: LIST 3153 Result: OK - append completed 3154 NO - append error: can't append to that mailbox, error 3155 in flags or date/time or message text 3156 BAD - command unknown or arguments invalid 3158 The APPEND command appends the literal argument as a new message to 3159 the end of the specified destination mailbox. This argument SHOULD 3160 be in the format of an [RFC-5322] or [I18N-HDRS] message. 8-bit 3161 characters are permitted in the message. A server implementation 3162 that is unable to preserve 8-bit data properly MUST be able to 3163 reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB] 3164 content transfer encoding. 3166 Note: There may be exceptions, e.g., draft messages, in which 3167 required [RFC-5322] header lines are omitted in the message 3168 literal argument to APPEND. The full implications of doing so 3169 must be understood and carefully weighed. 3171 If a flag parenthesized list is specified, the flags SHOULD be set in 3172 the resulting message; otherwise, the flag list of the resulting 3173 message is set to empty by default. 3175 If a date-time is specified, the internal date SHOULD be set in the 3176 resulting message; otherwise, the internal date of the resulting 3177 message is set to the current date and time by default. 3179 If the append is unsuccessful for any reason, the mailbox MUST be 3180 restored to its state before the APPEND attempt (other than possibly 3181 keeping the changed mailbox's UIDNEXT value); no partial appending is 3182 permitted. 3184 If the destination mailbox does not exist, a server MUST return an 3185 error, and MUST NOT automatically create the mailbox. Unless it is 3186 certain that the destination mailbox can not be created, the server 3187 MUST send the response code "[TRYCREATE]" as the prefix of the text 3188 of the tagged NO response. This gives a hint to the client that it 3189 can attempt a CREATE command and retry the APPEND if the CREATE is 3190 successful. 3192 On successful completion of an APPEND, the server SHOULD return an 3193 APPENDUID response code (see Section 7.1). 3195 In the case of a mailbox that has permissions set so that the client 3196 can APPEND to the mailbox, but not SELECT or EXAMINE it, the server 3197 SHOULD NOT send an APPENDUID response code as it would disclose 3198 information about the mailbox. 3200 In the case of a mailbox that has UIDNOTSTICKY status (see 3201 Section 7.1), the server MAY omit the APPENDUID response code as it 3202 is not meaningful. 3204 If the server does not return the APPENDUID response codes, the 3205 client can discover this information by selecting the destination 3206 mailbox. The location of messages placed in the destination mailbox 3207 by APPEND can be determined by using FETCH and/or SEARCH commands 3208 (e.g., for Message-ID or some unique marker placed in the message in 3209 an APPEND). 3211 If the mailbox is currently selected, the normal new message actions 3212 SHOULD occur. Specifically, the server SHOULD notify the client 3213 immediately via an untagged EXISTS response. If the server does not 3214 do so, the client MAY issue a NOOP command after one or more APPEND 3215 commands. 3217 If the server decides to convert (normalize) the mailbox name, it 3218 SHOULD return an untagged LIST with OLDNAME extended data item, with 3219 the OLDNAME value being the supplied mailbox name and the name 3220 parameter being the normalized mailbox name. (See Section 6.3.9.7 3221 for more details.) 3223 Example: C: A003 APPEND saved-messages (\Seen) {310} 3224 S: + Ready for literal data 3225 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3226 C: From: Fred Foobar 3227 C: Subject: afternoon meeting 3228 C: To: mooch@owatagu.siam.edu 3229 C: Message-Id: 3230 C: MIME-Version: 1.0 3231 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3232 C: 3233 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3234 C: 3235 S: A003 OK APPEND completed 3237 Example: C: A003 APPEND saved-messages (\Seen) {297} 3238 C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST) 3239 C: From: Fred Foobar 3240 C: Subject: afternoon meeting 3241 C: To: mooch@example.com 3242 C: Message-Id: 3243 C: MIME-Version: 1.0 3244 C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 3245 C: 3246 C: Hello Joe, do you think we can meet at 3:30 tomorrow? 3247 C: 3248 S: A003 OK [APPENDUID 38505 3955] APPEND completed 3249 C: A004 COPY 2:4 meeting 3250 S: A004 OK [COPYUID 38505 304,319:320 3956:3958] Done 3251 C: A005 UID COPY 305:310 meeting 3252 S: A005 OK No matching messages, so nothing copied 3253 C: A006 COPY 2 funny 3254 S: A006 OK Done 3255 C: A007 SELECT funny 3256 S: * 1 EXISTS 3257 S: * OK [UIDVALIDITY 3857529045] Validity session-only 3258 S: * OK [UIDNEXT 2] Predicted next UID 3259 S: * NO [UIDNOTSTICKY] Non-persistent UIDs 3260 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 3261 S: * OK [PERMANENTFLAGS (\Deleted \Seen)] Limited 3262 S: * LIST () "." funny 3263 S: A007 OK [READ-WRITE] SELECT completed 3265 In this example, A003 and A004 demonstrate successful appending and 3266 copying to a mailbox that returns the UIDs assigned to the messages. 3267 A005 is an example in which no messages were copied; this is because 3268 in A003, we see that message 2 had UID 304, and message 3 had UID 3269 319; therefore, UIDs 305 through 310 do not exist (refer to 3270 Section 2.3.1.1 for further explanation). A006 is an example of a 3271 message being copied that did not return a COPYUID; and, as expected, 3272 A007 shows that the mail store containing that mailbox does not 3273 support persistent UIDs. 3275 Note: The APPEND command is not used for message delivery, because 3276 it does not provide a mechanism to transfer [SMTP] envelope 3277 information. 3279 6.3.13. IDLE Command 3281 Arguments: none 3283 Responses: continuation data will be requested; the client sends the 3284 continuation data "DONE" to end the command 3286 Result: OK - IDLE completed after client sent "DONE" 3287 NO - failure: the server will not allow the IDLE command 3288 at this time 3289 BAD - command unknown or arguments invalid 3291 Without the IDLE command a client requires to poll the server for 3292 changes to the selected mailbox (new mail, deletions, flag changes). 3293 It's often more desirable to have the server transmit updates to the 3294 client in real time. This allows a user to see new mail immediately. 3295 The IDLE command allows a client to tell the server that it's ready 3296 to accept such real-time updates. 3298 The IDLE command is sent from the client to the server when the 3299 client is ready to accept unsolicited update messages. The server 3300 requests a response to the IDLE command using the continuation ("+") 3301 response. The IDLE command remains active until the client responds 3302 to the continuation, and as long as an IDLE command is active, the 3303 server is now free to send untagged EXISTS, EXPUNGE, FETCH, and other 3304 responses at any time. If the server choose to send unsolicited 3305 FETCH responses, they MUST include UID FETCH item. 3307 The IDLE command is terminated by the receipt of a "DONE" 3308 continuation from the client; such response satisfies the server's 3309 continuation request. At that point, the server MAY send any 3310 remaining queued untagged responses and then MUST immediately send 3311 the tagged response to the IDLE command and prepare to process other 3312 commands. As for other commands, the processing of any new command 3313 may cause the sending of unsolicited untagged responses, subject to 3314 the ambiguity limitations. The client MUST NOT send a command while 3315 the server is waiting for the DONE, since the server will not be able 3316 to distinguish a command from a continuation. 3318 The server MAY consider a client inactive if it has an IDLE command 3319 running, and if such a server has an inactivity timeout it MAY log 3320 the client off implicitly at the end of its timeout period. Because 3321 of that, clients using IDLE are advised to terminate the IDLE and re- 3322 issue it at least every 29 minutes to avoid being logged off. This 3323 still allows a client to receive immediate mailbox updates even 3324 though it need only "poll" at half hour intervals. 3326 Example: C: A001 SELECT INBOX 3327 S: * FLAGS (\Deleted \Seen \Flagged) 3328 S: * OK [PERMANENTFLAGS (\Deleted \Seen \Flagged)] Limited 3329 S: * 3 EXISTS 3330 S: * OK [UIDVALIDITY 1] 3331 S: * LIST () "/" INBOX 3332 S: A001 OK [READ-WRITE] SELECT completed 3333 C: A002 IDLE 3334 S: + idling 3335 ...time passes; new mail arrives... 3336 S: * 4 EXISTS 3337 C: DONE 3338 S: A002 OK IDLE terminated 3339 ...another client expunges message 2 now... 3340 C: A003 FETCH 4 ALL 3341 S: * 4 FETCH (...) 3342 S: A003 OK FETCH completed 3343 C: A004 IDLE 3344 S: * 2 EXPUNGE 3345 S: * 3 EXISTS 3346 S: + idling 3347 ...time passes; another client expunges message 3... 3348 S: * 3 EXPUNGE 3349 S: * 2 EXISTS 3350 ...time passes; new mail arrives... 3351 S: * 3 EXISTS 3352 C: DONE 3353 S: A004 OK IDLE terminated 3354 C: A005 FETCH 3 ALL 3355 S: * 3 FETCH (...) 3356 S: A005 OK FETCH completed 3357 C: A006 IDLE 3359 6.4. Client Commands - Selected State 3361 In the selected state, commands that manipulate messages in a mailbox 3362 are permitted. 3364 In addition to the universal commands (CAPABILITY, NOOP, and LOGOUT), 3365 and the authenticated state commands (SELECT, EXAMINE, NAMESPACE, 3366 CREATE, DELETE, RENAME, SUBSCRIBE, UNSUBSCRIBE, LIST, STATUS, and 3367 APPEND), the following commands are valid in the selected state: 3368 CLOSE, UNSELECT, EXPUNGE, SEARCH, FETCH, STORE, COPY, MOVE, and UID. 3370 6.4.1. CLOSE Command 3372 Arguments: none 3374 Responses: no specific responses for this command 3376 Result: OK - close completed, now in authenticated state 3377 BAD - command unknown or arguments invalid 3379 The CLOSE command permanently removes all messages that have the 3380 \Deleted flag set from the currently selected mailbox, and returns to 3381 the authenticated state from the selected state. No untagged EXPUNGE 3382 responses are sent. 3384 No messages are removed, and no error is given, if the mailbox is 3385 selected by an EXAMINE command or is otherwise selected read-only. 3387 Even if a mailbox is selected, a SELECT, EXAMINE, or LOGOUT command 3388 MAY be issued without previously issuing a CLOSE command. The 3389 SELECT, EXAMINE, and LOGOUT commands implicitly close the currently 3390 selected mailbox without doing an expunge. However, when many 3391 messages are deleted, a CLOSE-LOGOUT or CLOSE-SELECT sequence is 3392 considerably faster than an EXPUNGE-LOGOUT or EXPUNGE-SELECT because 3393 no untagged EXPUNGE responses (which the client would probably 3394 ignore) are sent. 3396 Example: C: A341 CLOSE 3397 S: A341 OK CLOSE completed 3399 6.4.2. UNSELECT Command 3401 Arguments: none 3403 Responses: no specific responses for this command 3405 Result: OK - unselect completed, now in authenticated state 3406 BAD - no mailbox selected, or argument supplied but none 3407 permitted 3409 The UNSELECT command frees server's resources associated with the 3410 selected mailbox and returns the server to the authenticated state. 3411 This command performs the same actions as CLOSE, except that no 3412 messages are permanently removed from the currently selected mailbox. 3414 Example: C: A342 UNSELECT 3415 S: A342 OK Unselect completed 3417 6.4.3. EXPUNGE Command 3419 Arguments: none 3421 Responses: untagged responses: EXPUNGE 3423 Result: OK - expunge completed 3424 NO - expunge failure: can't expunge (e.g., permission 3425 denied) 3426 BAD - command unknown or arguments invalid 3428 The EXPUNGE command permanently removes all messages that have the 3429 \Deleted flag set from the currently selected mailbox. Before 3430 returning an OK to the client, an untagged EXPUNGE response is sent 3431 for each message that is removed. 3433 Example: C: A202 EXPUNGE 3434 S: * 3 EXPUNGE 3435 S: * 3 EXPUNGE 3436 S: * 5 EXPUNGE 3437 S: * 8 EXPUNGE 3438 S: A202 OK EXPUNGE completed 3440 Note: In this example, messages 3, 4, 7, and 11 had the \Deleted flag 3441 set. See the description of the EXPUNGE response for further 3442 explanation. 3444 6.4.4. SEARCH Command 3446 Arguments: OPTIONAL result specifier 3447 OPTIONAL [CHARSET] specification 3448 searching criteria (one or more) 3450 Responses: OPTIONAL untagged response: ESEARCH 3452 Result: OK - search completed 3453 NO - search error: can't search that [CHARSET] or 3454 criteria 3455 BAD - command unknown or arguments invalid 3457 The SEARCH command searches the mailbox for messages that match the 3458 given searching criteria. 3460 The SEARCH command may contain result options. Result options 3461 control what kind of information is returned about messages matching 3462 the search criteria in an untagged ESEARCH response. If no result 3463 option is specified or empty list of options is specified "()", ALL 3464 is assumed (see below). The order of individual options is 3465 arbitrary. Individual options may contain parameters enclosed in 3466 parentheses (*). If an option has parameters, they consist of atoms 3467 and/or strings and/or lists in a specific order. Any options not 3468 defined by extensions that the server supports must be rejected with 3469 a BAD response. 3471 (*) - if an option has a mandatory parameter, which can always be 3472 represented as a number or a sequence-set, the option parameter does 3473 not need the enclosing (). See the ABNF for more details. 3475 This document specifies the following result options: 3477 MIN 3479 Return the lowest message number/UID that satisfies the SEARCH 3480 criteria. 3482 If the SEARCH results in no matches, the server MUST NOT 3483 include the MIN result option in the ESEARCH response; however, 3484 it still MUST send the ESEARCH response. 3486 MAX 3488 Return the highest message number/UID that satisfies the SEARCH 3489 criteria. 3491 If the SEARCH results in no matches, the server MUST NOT 3492 include the MAX result option in the ESEARCH response; however, 3493 it still MUST send the ESEARCH response. 3495 ALL 3497 Return all message numbers/UIDs that satisfy the SEARCH 3498 criteria using the sequence-set syntax. Note, the client MUST 3499 NOT assume that messages/UIDs will be listed in any particular 3500 order. 3502 If the SEARCH results in no matches, the server MUST NOT 3503 include the ALL result option in the ESEARCH response; however, 3504 it still MUST send the ESEARCH response. 3506 COUNT Return number of the messages that satisfy the SEARCH 3507 criteria. This result option MUST always be included in the 3508 ESEARCH response. 3510 SAVE 3511 This option tells the server to remember the result of the 3512 SEARCH or UID SEARCH command (as well as any command based on 3513 SEARCH, e.g., SORT and THREAD [RFC5256]>) and store it in an 3514 internal variable that we will reference as the "search result 3515 variable". The client can use the "$" marker to reference the 3516 content of this internal variable. The "$" marker can be used 3517 instead of message sequence or UID sequence in order to 3518 indicate that the server should substitute it with the list of 3519 messages from the search result variable. Thus, the client can 3520 use the result of the latest remembered SEARCH command as a 3521 parameter to another command. See Section 6.4.4.1 for details 3522 on how the value of the search result variable is determined, 3523 how it is affected by other commands executed, and how SAVE 3524 return option interacts with other return options. 3526 In absence of any other SEARCH result option, the SAVE result 3527 option also suppresses any ESEARCH response that would have 3528 been otherwise returned by the SEARCH command. 3530 Note: future extensions to this document can allow servers to return 3531 multiple ESEARCH responses for a single extended SEARCH command. 3532 However all options specified above MUST result in a single ESEARCH 3533 response if used by themselves or in a combination. This guaranty 3534 simplifies processing in IMAP4rev2 clients. Future SEARCH extensions 3535 that relax this restriction will have to describe how results from 3536 multiple ESEARCH responses are to be amalgamated. 3538 Searching criteria consist of one or more search keys. 3540 When multiple keys are specified, the result is the intersection (AND 3541 function) of all the messages that match those keys. For example, 3542 the criteria DELETED FROM "SMITH" SINCE 1-Feb-1994 refers to all 3543 deleted messages from Smith with INTERNALDATE greater than February 3544 1, 1994. A search key can also be a parenthesized list of one or 3545 more search keys (e.g., for use with the OR and NOT keys). 3547 Server implementations MAY exclude [MIME-IMB] body parts with 3548 terminal content media types other than TEXT and MESSAGE from 3549 consideration in SEARCH matching. 3551 The OPTIONAL [CHARSET] specification consists of the word "CHARSET" 3552 followed by a registered [CHARSET] [CHARSET-REG]. It indicates the 3553 [CHARSET] of the strings that appear in the search criteria. 3554 [MIME-IMB] content transfer encodings, and [MIME-HDRS] strings in 3555 [RFC-5322]/[MIME-IMB] headers, MUST be decoded before comparing text. 3556 Servers MUST support US-ASCII and UTF-8 charsets; other [CHARSET]s 3557 MAY be supported. Clients SHOULD use UTF-8. Note that if "CHARSET" 3558 is not provided IMAP4rev2 server MUST assume UTF-8, so selecting 3559 CHARSET UTF-8 is redundant. It is permitted for improved 3560 compatibility with existing IMAP4rev1 clients. 3562 If the server does not support the specified [CHARSET], it MUST 3563 return a tagged NO response (not a BAD). This response SHOULD 3564 contain the BADCHARSET response code, which MAY list the [CHARSET]s 3565 supported by the server. 3567 In all search keys that use strings and unless specified otherwise, a 3568 message matches the key if the string is a substring of the 3569 associated text. The matching SHOULD be case-insensitive for 3570 characters within ASCII range. Consider using [IMAP-I18N] for 3571 language-sensitive case-insensitive searching. Note that the empty 3572 string is a substring; this is useful when doing a HEADER search in 3573 order to test for a header field presence in the message. 3575 The defined search keys are as follows. Refer to the Formal Syntax 3576 section for the precise syntactic definitions of the arguments. 3578 Messages with message sequence numbers corresponding 3579 to the specified message sequence number set. 3581 ALL All messages in the mailbox; the default initial key for ANDing. 3583 ANSWERED Messages with the \Answered flag set. 3585 BCC Messages that contain the specified string in the 3586 envelope structure's BCC field. 3588 BEFORE Messages whose internal date (disregarding time and 3589 timezone) is earlier than the specified date. 3591 BODY Messages that contain the specified string in the body 3592 of the message. Unlike TEXT (see below), this doesn't match any 3593 header fields. Servers are allowed to implement flexible matching 3594 for this search key, for example matching "swim" to both "swam" 3595 and "swum" in English language text or only doing full word 3596 matching (where "swim" will not match "swimming"). 3598 CC Messages that contain the specified string in the 3599 envelope structure's CC field. 3601 DELETED Messages with the \Deleted flag set. 3603 DRAFT Messages with the \Draft flag set. 3605 FLAGGED Messages with the \Flagged flag set. 3607 FROM Messages that contain the specified string in the 3608 envelope structure's FROM field. 3610 HEADER Messages that have a header with the 3611 specified field-name (as defined in [RFC-5322]) and that contains 3612 the specified string in the text of the header (what comes after 3613 the colon). If the string to search is zero-length, this matches 3614 all messages that have a header line with the specified field-name 3615 regardless of the contents. Servers should use substring search 3616 for this SEARCH item, as clients can use it for automatic 3617 processing not initiated by end users. For example this can be 3618 used for searching for Message-ID or Content-Type header field 3619 values that need to be exact, or for searches in header fields 3620 that the IMAP server might not know anything about. 3622 KEYWORD Messages with the specified keyword flag set. 3624 LARGER Messages with an [RFC-5322] size larger than the 3625 specified number of octets. 3627 NOT Messages that do not match the specified search 3628 key. 3630 ON Messages whose internal date (disregarding time and 3631 timezone) is within the specified date. 3633 OR Messages that match either search 3634 key. 3636 SEEN Messages that have the \Seen flag set. 3638 SENTBEFORE Messages whose [RFC-5322] Date: header 3639 (disregarding time and timezone) is earlier than the specified 3640 date. 3642 SENTON Messages whose [RFC-5322] Date: header (disregarding 3643 time and timezone) is within the specified date. 3645 SENTSINCE Messages whose [RFC-5322] Date: header 3646 (disregarding time and timezone) is within or later than the 3647 specified date. 3649 SINCE Messages whose internal date (disregarding time and 3650 timezone) is within or later than the specified date. 3652 SMALLER Messages with an [RFC-5322] size smaller than the 3653 specified number of octets. 3655 SUBJECT Messages that contain the specified string in the 3656 envelope structure's SUBJECT field. 3658 TEXT Messages that contain the specified string in the 3659 header (including MIME header fields) or body of the message. 3660 Servers are allowed to implement flexible matching for this search 3661 key, for example matching "swim" to both "swam" and "swum" in 3662 English language text or only doing full word matching (where 3663 "swim" will not match "swimming"). 3665 TO Messages that contain the specified string in the 3666 envelope structure's TO field. 3668 UID Messages with unique identifiers corresponding to 3669 the specified unique identifier set. Sequence set ranges are 3670 permitted. 3672 UNANSWERED Messages that do not have the \Answered flag set. 3674 UNDELETED Messages that do not have the \Deleted flag set. 3676 UNDRAFT Messages that do not have the \Draft flag set. 3678 UNFLAGGED Messages that do not have the \Flagged flag set. 3680 UNKEYWORD Messages that do not have the specified keyword 3681 flag set. 3683 UNSEEN Messages that do not have the \Seen flag set. 3685 Example: C: A282 SEARCH RETURN (MIN COUNT) FLAGGED 3686 SINCE 1-Feb-1994 NOT FROM "Smith" 3687 S: * ESEARCH (TAG "A282") MIN 2 COUNT 3 3688 S: A282 OK SEARCH completed 3690 Example: C: A283 SEARCH RETURN () FLAGGED 3691 SINCE 1-Feb-1994 NOT FROM "Smith" 3692 S: * ESEARCH (TAG "A283") ALL 2,10:11 3693 S: A283 OK SEARCH completed 3695 Example: C: A284 SEARCH TEXT "string not in mailbox" 3696 S: * ESEARCH (TAG "A284") 3697 S: A284 OK SEARCH completed 3698 C: A285 SEARCH CHARSET UTF-8 TEXT {6} 3699 S: + Ready for literal text 3700 C: XXXXXX 3701 S: * ESEARCH (TAG "A285") ALL 43 3702 S: A285 OK SEARCH completed 3704 Note: Since this document is restricted to 7-bit ASCII text, it is 3705 not possible to show actual UTF-8 data. The "XXXXXX" is a 3706 placeholder for what would be 6 octets of 8-bit data in an actual 3707 transaction. 3709 The following example demonstrates finding the first unseen message 3710 in the mailbox: 3712 Example: C: A284 SEARCH RETURN (MIN) UNSEEN 3713 S: * ESEARCH (TAG "A284") MIN 4 3714 S: A284 OK SEARCH completed 3716 The following example demonstrates that if the ESEARCH UID indicator 3717 is present, all data in the ESEARCH response is referring to UIDs; 3718 for example, the MIN result specifier will be followed by a UID. 3720 Example: C: A285 UID SEARCH RETURN (MIN MAX) 1:5000 3721 S: * ESEARCH (TAG "A285") UID MIN 7 MAX 3800 3722 S: A285 OK SEARCH completed 3724 The following example demonstrates returning the number of deleted 3725 messages: 3727 Example: C: A286 SEARCH RETURN (COUNT) DELETED 3728 S: * ESEARCH (TAG "A286") COUNT 15 3729 S: A286 OK SEARCH completed 3731 6.4.4.1. SAVE result option and SEARCH result variable 3733 Upon successful completion of a SELECT or an EXAMINE command (after 3734 the tagged OK response), the current search result variable is reset 3735 to the empty sequence. 3737 A successful SEARCH command with the SAVE result option sets the 3738 value of the search result variable to the list of messages found in 3739 the SEARCH command. For example, if no messages were found, the 3740 search result variable will contain the empty sequence. 3742 Any of the following SEARCH commands MUST NOT change the search 3743 result variable: 3745 a SEARCH command that caused the server to return the BAD tagged 3746 response, 3748 a SEARCH command with no SAVE result option that caused the server 3749 to return NO tagged response, 3751 a successful SEARCH command with no SAVE result option. 3753 A SEARCH command with the SAVE result option that caused the server 3754 to return the NO tagged response sets the value of the search result 3755 variable to the empty sequence. 3757 When a message listed in the search result variable is EXPUNGEd, it 3758 is automatically removed from the list. Implementors are reminded 3759 that if the server stores the list as a list of message numbers, it 3760 MUST automatically adjust them when notifying the client about 3761 expunged messages, as described in Section 7.4.1. 3763 If the server decides to send a new UIDVALIDITY value while the 3764 mailbox is opened, this causes resetting of the search variable to 3765 the empty sequence. 3767 Note that even if the "$" marker contains the empty sequence of 3768 messages, it must be treated by all commands accepting message sets 3769 as parameters as a valid, but non-matching list of messages. For 3770 example, the "FETCH $" command would return a tagged OK response and 3771 no FETCH responses. See also the Example 5 in Section 6.4.4.4. 3773 The SAVE result option doesn't change whether the server would return 3774 items corresponding to MIN, MAX, ALL, or COUNT result options. 3776 When the SAVE result option is combined with the MIN or MAX result 3777 option, and both ALL and COUNT result options are absent, the 3778 corresponding MIN/MAX is returned (if the search result is not 3779 empty), but the "$" marker would contain a single message as returned 3780 in the MIN/MAX return item. 3782 If the SAVE result option is combined with both MIN and MAX result 3783 options, and both ALL and COUNT result options are absent, the "$" 3784 marker would contain zero, one or two messages as returned in the 3785 MIN/MAX return items. 3787 If the SAVE result option is combined with the ALL and/or COUNT 3788 result option(s), the "$" marker would always contain all messages 3789 found by the SEARCH or UID SEARCH command. 3791 The following table summarizes the additional requirement on ESEARCH 3792 server implementations described in this section. 3794 +------------------------------+--------------------+ 3795 | Combination of Result option | "$" marker value | 3796 +------------------------------+--------------------+ 3797 | SAVE MIN | MIN | 3798 | SAVE MAX | MAX | 3799 | SAVE MIN MAX | MIN & MAX | 3800 | SAVE * [m] | all found messages | 3801 +------------------------------+--------------------+ 3803 where '*' means "ALL" and/or "COUNT", and '[m]' means optional "MIN" 3804 and/or "MAX" 3806 Implementation note: server implementors should note that "$" can 3807 reference IMAP message sequences or UID sequences, depending on the 3808 context where it is used. For example, the "$" marker can be set as 3809 a result of a SEARCH (SAVE) command and used as a parameter to a UID 3810 FETCH command (which accepts a UID sequence, not a message sequence), 3811 or the "$" marker can be set as a result of a UID SEARCH (SAVE) 3812 command and used as a parameter to a FETCH command (which accepts a 3813 message sequence, not a UID sequence). Server implementations need 3814 to automatically map the "$" marker value to message numbers or UIDs, 3815 depending on context where the "$" marker is used. 3817 6.4.4.2. Multiple Commands in Progress 3819 Use of a SEARCH RETURN (SAVE) command followed by a command using the 3820 "$" marker creates direct dependency between the two commands. As 3821 directed by Section 5.5, a server MUST execute the two commands in 3822 the order they were received. 3824 A client MAY pipeline a SEARCH RETURN (SAVE) command with one or more 3825 command using the "$" marker, as long as this doesn't create an 3826 ambiguity, as described in by Section 5.5. Examples 7-9 in 3827 Section 6.4.4.4 explain this in more details. 3829 6.4.4.3. Refusing to Save Search Results 3831 In some cases, the server MAY refuse to save a SEARCH (SAVE) result, 3832 for example, if an internal limit on the number of saved results is 3833 reached. In this case, the server MUST return a tagged NO response 3834 containing the NOTSAVED response code and set the search result 3835 variable to the empty sequence, as described in Section 6.4.4.1. 3837 6.4.4.4. Examples showing use of SAVE result option 3839 Only in this section: explanatory comments in examples that start 3840 with // are not part of the protocol. 3842 1) The following example demonstrates how the client can use the 3843 result of a SEARCH command to FETCH headers of interesting messages: 3845 Example 1: 3846 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3847 NOT FROM "Smith" 3848 S: A282 OK SEARCH completed, result saved 3849 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3850 S: * 2 FETCH (UID 14 ... 3851 S: * 84 FETCH (UID 100 ... 3852 S: * 882 FETCH (UID 1115 ... 3853 S: A283 OK completed 3855 The client can also pipeline the two commands: 3857 Example 2: 3858 C: A282 SEARCH RETURN (SAVE) FLAGGED SINCE 1-Feb-1994 3859 NOT FROM "Smith" 3860 C: A283 FETCH $ (UID INTERNALDATE FLAGS BODY.PEEK[HEADER]) 3861 S: A282 OK SEARCH completed 3862 S: * 2 FETCH (UID 14 ... 3863 S: * 84 FETCH (UID 100 ... 3864 S: * 882 FETCH (UID 1115 ... 3865 S: A283 OK completed 3867 2) The following example demonstrates that the result of one SEARCH 3868 command can be used as input to another SEARCH command: 3870 Example 3: 3871 C: A300 SEARCH RETURN (SAVE) SINCE 1-Jan-2004 3872 NOT FROM "Smith" 3873 S: A300 OK SEARCH completed 3874 C: A301 UID SEARCH UID $ SMALLER 4096 3875 S: * ESEARCH (TAG "A301") UID ALL 17,900,901 3876 S: A301 OK completed 3878 Note that the second command in Example 3 can be replaced with: 3879 C: A301 UID SEARCH $ SMALLER 4096 3880 and the result of the command would be the same. 3882 3) The following example shows that the "$" marker can be combined 3883 with other message numbers using the OR SEARCH criterion. 3885 Example 4: 3886 C: P282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3887 NOT FROM "Smith" 3888 S: P282 OK SEARCH completed 3889 C: P283 SEARCH CHARSET UTF-8 (OR $ 1,3000:3021) TEXT {8} 3890 C: YYYYYYYY 3891 S: * ESEARCH (TAG "P283") ALL 882,1102,3003,3005:3006 3892 S: P283 OK completed 3894 Note: Since this document format is restricted to 7-bit ASCII text, 3895 it is not possible to show actual UTF-8 data. The "YYYYYYYY" is a 3896 placeholder for what would be 8 octets of 8-bit data in an actual 3897 transaction. 3899 4) The following example demonstrates that a failed SEARCH sets the 3900 search result variable to the empty list. The server doesn't 3901 implement the KOI8-R charset. 3903 Example 5: 3904 C: B282 SEARCH RETURN (SAVE) SINCE 1-Feb-1994 3905 NOT FROM "Smith" 3906 S: B282 OK SEARCH completed 3907 C: B283 SEARCH RETURN (SAVE) CHARSET KOI8-R 3908 (OR $ 1,3000:3021) TEXT {4} 3909 C: XXXX 3910 S: B283 NO [BADCHARSET UTF-8] KOI8-R is not supported 3911 //After this command the saved result variable contains 3912 //no messages. A client that wants to reissue the B283 3913 //SEARCH command with another CHARSET would have to reissue 3914 //the B282 command as well. One possible workaround for 3915 //this is to include the desired CHARSET parameter 3916 //in the earliest SEARCH RETURN (SAVE) command in a 3917 //sequence of related SEARCH commands, to cause 3918 //the earliest SEARCH in the sequence to fail. 3919 //A better approach might be to always use CHARSET UTF-8 3920 //instead. 3922 Note: Since this document format is restricted to 7-bit ASCII text, 3923 it is not possible to show actual KOI8-R data. The "XXXX" is a 3924 placeholder for what would be 4 octets of 8-bit data in an actual 3925 transaction. 3927 5) The following example demonstrates that it is not an error to use 3928 the "$" marker when it contains no messages. 3930 Example 6: 3931 C: E282 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3932 NOT FROM "Eric" 3933 C: E283 COPY $ "Other Messages" 3934 //The "$" contains no messages 3935 S: E282 OK SEARCH completed 3936 S: E283 OK COPY completed, nothing copied 3938 Example 7: 3939 C: F282 SEARCH RETURN (SAVE) KEYWORD $Junk 3940 C: F283 COPY $ "Junk" 3941 C: F284 STORE $ +FLAGS.Silent (\Deleted) 3942 S: F282 OK SEARCH completed 3943 S: F283 OK COPY completed 3944 S: F284 OK STORE completed 3946 Example 8: 3947 C: G282 SEARCH RETURN (SAVE) KEYWORD $Junk 3948 C: G283 SEARCH RETURN (ALL) SINCE 28-Oct-2006 3949 FROM "Eric" 3950 // The server can execute the two SEARCH commands 3951 // in any order, as they don't have any dependency. 3952 // For example, it may return: 3953 S: * ESEARCH (TAG "G283") ALL 3:15,27,29:103 3954 S: G283 OK SEARCH completed 3955 S: G282 OK SEARCH completed 3957 The following example demonstrates that the result of the second 3958 SEARCH RETURN (SAVE) always overrides the result of the first. 3960 Example 9: 3961 C: H282 SEARCH RETURN (SAVE) KEYWORD $Junk 3962 C: H283 SEARCH RETURN (SAVE) SINCE 28-Oct-2006 3963 FROM "Eric" 3964 S: H282 OK SEARCH completed 3965 S: H283 OK SEARCH completed 3966 // At this point "$" would contain results of H283 3968 The following example demonstrates behavioral difference for 3969 different combinations of ESEARCH result options. 3971 Example 10: 3972 C: C282 SEARCH RETURN (ALL) SINCE 12-Feb-2006 3973 NOT FROM "Smith" 3974 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3975 //$ value hasn't changed 3976 S: C282 OK SEARCH completed 3978 C: C283 SEARCH RETURN (ALL SAVE) SINCE 12-Feb-2006 3979 NOT FROM "Smith" 3980 S: * ESEARCH (TAG "C283") ALL 2,10:15,21 3981 //$ value is 2,10:15,21 3982 S: C283 OK SEARCH completed 3984 C: C284 SEARCH RETURN (SAVE MIN) SINCE 12-Feb-2006 3985 NOT FROM "Smith" 3986 S: * ESEARCH (TAG "C284") MIN 2 3987 //$ value is 2 3988 S: C284 OK SEARCH completed 3990 C: C285 SEARCH RETURN (MAX SAVE MIN) SINCE 3991 12-Feb-2006 NOT FROM "Smith" 3992 S: * ESEARCH (TAG "C285") MIN 2 MAX 21 3993 //$ value is 2,21 3994 S: C285 OK SEARCH completed 3996 C: C286 SEARCH RETURN (MAX SAVE MIN COUNT) 3997 SINCE 12-Feb-2006 NOT FROM "Smith" 3998 S: * ESEARCH (TAG "C286") MIN 2 MAX 21 COUNT 8 3999 //$ value is 2,10:15,21 4000 S: C286 OK SEARCH completed 4002 C: C286 SEARCH RETURN (ALL SAVE MIN) SINCE 4003 12-Feb-2006 NOT FROM "Smith" 4004 S: * ESEARCH (TAG "C286") MIN 2 ALL 2,10:15,21 4005 //$ value is 2,10:15,21 4006 S: C286 OK SEARCH completed 4008 6.4.5. FETCH Command 4010 Arguments: sequence set 4011 message data item names or macro 4013 Responses: untagged responses: FETCH 4015 Result: OK - fetch completed 4016 NO - fetch error: can't fetch that data 4017 BAD - command unknown or arguments invalid 4019 The FETCH command retrieves data associated with a message in the 4020 mailbox. The data items to be fetched can be either a single atom or 4021 a parenthesized list. 4023 Most data items, identified in the formal syntax under the msg-att- 4024 static rule, are static and MUST NOT change for any particular 4025 message. Other data items, identified in the formal syntax under the 4026 msg-att-dynamic rule, MAY change, either as a result of a STORE 4027 command or due to external events. 4029 For example, if a client receives an ENVELOPE for a message when 4030 it already knows the envelope, it can safely ignore the newly 4031 transmitted envelope. 4033 There are three macros which specify commonly-used sets of data 4034 items, and can be used instead of data items. A macro must be used 4035 by itself, and not in conjunction with other macros or data items. 4037 ALL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE) 4039 FAST Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE) 4041 FULL Macro equivalent to: (FLAGS INTERNALDATE RFC822.SIZE ENVELOPE 4042 BODY) 4044 Several data items reference "section" or "section-binary". See 4045 Section 6.4.5.1 for their detailed definition. 4047 The currently defined data items that can be fetched are: 4049 BINARY[]<> 4051 Requests that the specified section be transmitted after 4052 performing Content-Transfer-Encoding-related decoding. 4054 The argument, if present, requests that a subset of 4055 the data be returned. The semantics of a partial FETCH BINARY 4056 command are the same as for a partial FETCH BODY command, with 4057 the exception that the arguments refer to the DECODED 4058 section data. 4060 Note that this data item can only be requested for leaf (i.e. 4061 non multipart/*, non message/rfc822 and non message/global) 4062 body parts. 4064 BINARY.PEEK[]<> An alternate form of 4065 BINARY[] that does not implicitly set the \Seen 4066 flag. 4068 BINARY.SIZE[] 4070 Requests the decoded size of the section (i.e., the size to 4071 expect in response to the corresponding FETCH BINARY request). 4073 Note: client authors are cautioned that this might be an 4074 expensive operation for some server implementations. 4075 Needlessly issuing this request could result in degraded 4076 performance due to servers having to calculate the value every 4077 time the request is issued. 4079 Note that this data item can only be requested for leaf (i.e. 4080 non multipart/*, non message/rfc822 and non message/global) 4081 body parts. 4083 BODY Non-extensible form of BODYSTRUCTURE. 4085 BODY[
]<> 4087 The text of a particular body section. 4089 It is possible to fetch a substring of the designated text. 4090 This is done by appending an open angle bracket ("<"), the 4091 octet position of the first desired octet, a period, the 4092 maximum number of octets desired, and a close angle bracket 4093 (">") to the part specifier. If the starting octet is beyond 4094 the end of the text, an empty string is returned. 4096 Any partial fetch that attempts to read beyond the end of the 4097 text is truncated as appropriate. A partial fetch that starts 4098 at octet 0 is returned as a partial fetch, even if this 4099 truncation happened. 4101 Note: This means that BODY[]<0.2048> of a 1500-octet message 4102 will return BODY[]<0> with a literal of size 1500, not 4103 BODY[]. 4105 Note: A substring fetch of a HEADER.FIELDS or 4106 HEADER.FIELDS.NOT part specifier is calculated after 4107 subsetting the header. 4109 The \Seen flag is implicitly set; if this causes the flags to 4110 change, they SHOULD be included as part of the FETCH responses. 4112 BODY.PEEK[
]<> An alternate form of BODY[
] 4113 that does not implicitly set the \Seen flag. 4115 BODYSTRUCTURE The [MIME-IMB] body structure of the message. This is 4116 computed by the server by parsing the [MIME-IMB] header fields in 4117 the [RFC-5322] header and [MIME-IMB] headers. See Section 7.4.2 4118 for more details. 4120 ENVELOPE The envelope structure of the message. This is computed by 4121 the server by parsing the [RFC-5322] header into the component 4122 parts, defaulting various fields as necessary. See Section 7.4.2 4123 for more details. 4125 FLAGS The flags that are set for this message. 4127 INTERNALDATE The internal date of the message. 4129 RFC822.SIZE The [RFC-5322] size of the message. 4131 UID The unique identifier for the message. 4133 Example: C: A654 FETCH 2:4 (FLAGS BODY[HEADER.FIELDS (DATE FROM)]) 4134 S: * 2 FETCH .... 4135 S: * 3 FETCH .... 4136 S: * 4 FETCH .... 4137 S: A654 OK FETCH completed 4139 6.4.5.1. FETCH section specification 4141 Several FETCH data items reference "section" or "section-binary". 4142 The section specification is a set of zero or more part specifiers 4143 delimited by periods. A part specifier is either a part number or 4144 one of the following: HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, MIME, 4145 and TEXT. (Non numeric part specifiers have to be the last specifier 4146 in a section specification.) An empty section specification refers 4147 to the entire message, including the header. 4149 Every message has at least one part number. Non-[MIME-IMB] messages, 4150 and non-multipart [MIME-IMB] messages with no encapsulated message, 4151 only have a part 1. 4153 Multipart messages are assigned consecutive part numbers, as they 4154 occur in the message. If a particular part is of type message or 4155 multipart, its parts MUST be indicated by a period followed by the 4156 part number within that nested multipart part. 4158 A part of type MESSAGE/RFC822 or MESSAGE/GLOBAL also has nested part 4159 numbers, referring to parts of the MESSAGE part's body. 4161 The HEADER, HEADER.FIELDS, HEADER.FIELDS.NOT, and TEXT part 4162 specifiers can be the sole part specifier or can be prefixed by one 4163 or more numeric part specifiers, provided that the numeric part 4164 specifier refers to a part of type MESSAGE/RFC822 or MESSAGE/GLOBAL. 4165 The MIME part specifier MUST be prefixed by one or more numeric part 4166 specifiers. 4168 The HEADER, HEADER.FIELDS, and HEADER.FIELDS.NOT part specifiers 4169 refer to the [RFC-5322] header of the message or of an encapsulated 4170 [MIME-IMT] MESSAGE/RFC822 or MESSAGE/GLOBAL message. HEADER.FIELDS 4171 and HEADER.FIELDS.NOT are followed by a list of field-name (as 4172 defined in [RFC-5322]) names, and return a subset of the header. The 4173 subset returned by HEADER.FIELDS contains only those header fields 4174 with a field-name that matches one of the names in the list; 4175 similarly, the subset returned by HEADER.FIELDS.NOT contains only the 4176 header fields with a non-matching field-name. The field-matching is 4177 ASCII range case-insensitive but otherwise exact. Subsetting does 4178 not exclude the [RFC-5322] delimiting blank line between the header 4179 and the body; the blank line is included in all header fetches, 4180 except in the case of a message which has no body and no blank line. 4182 The MIME part specifier refers to the [MIME-IMB] header for this 4183 part. 4185 The TEXT part specifier refers to the text body of the message, 4186 omitting the [RFC-5322] header. 4188 Here is an example of a complex message with some of its part 4189 specifiers: 4191 HEADER ([RFC-5322] header of the message) 4192 TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4193 1 TEXT/PLAIN 4194 2 APPLICATION/OCTET-STREAM 4195 3 MESSAGE/RFC822 4196 3.HEADER ([RFC-5322] header of the message) 4197 3.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4198 3.1 TEXT/PLAIN 4199 3.2 APPLICATION/OCTET-STREAM 4200 4 MULTIPART/MIXED 4201 4.1 IMAGE/GIF 4202 4.1.MIME ([MIME-IMB] header for the IMAGE/GIF) 4203 4.2 MESSAGE/RFC822 4204 4.2.HEADER ([RFC-5322] header of the message) 4205 4.2.TEXT ([RFC-5322] text body of the message) MULTIPART/MIXED 4206 4.2.1 TEXT/PLAIN 4207 4.2.2 MULTIPART/ALTERNATIVE 4208 4.2.2.1 TEXT/PLAIN 4209 4.2.2.2 TEXT/RICHTEXT 4211 6.4.6. STORE Command 4213 Arguments: sequence set 4214 message data item name 4215 value for message data item 4217 Responses: untagged responses: FETCH 4219 Result: OK - store completed 4220 NO - store error: can't store that data 4221 BAD - command unknown or arguments invalid 4223 The STORE command alters data associated with a message in the 4224 mailbox. Normally, STORE will return the updated value of the data 4225 with an untagged FETCH response. A suffix of ".SILENT" in the data 4226 item name prevents the untagged FETCH, and the server SHOULD assume 4227 that the client has determined the updated value itself or does not 4228 care about the updated value. 4230 Note: Regardless of whether or not the ".SILENT" suffix was used, 4231 the server SHOULD send an untagged FETCH response if a change to a 4232 message's flags from an external source is observed. The intent 4233 is that the status of the flags is determinate without a race 4234 condition. 4236 The currently defined data items that can be stored are: 4238 FLAGS Replace the flags for the message with the 4239 argument. The new value of the flags is returned as if a FETCH of 4240 those flags was done. 4242 FLAGS.SILENT Equivalent to FLAGS, but without returning 4243 a new value. 4245 +FLAGS Add the argument to the flags for the message. 4246 The new value of the flags is returned as if a FETCH of those 4247 flags was done. 4249 +FLAGS.SILENT Equivalent to +FLAGS, but without 4250 returning a new value. 4252 -FLAGS Remove the argument from the flags for the 4253 message. The new value of the flags is returned as if a FETCH of 4254 those flags was done. 4256 -FLAGS.SILENT Equivalent to -FLAGS, but without 4257 returning a new value. 4259 Example: C: A003 STORE 2:4 +FLAGS (\Deleted) 4260 S: * 2 FETCH (FLAGS (\Deleted \Seen)) 4261 S: * 3 FETCH (FLAGS (\Deleted)) 4262 S: * 4 FETCH (FLAGS (\Deleted \Flagged \Seen)) 4263 S: A003 OK STORE completed 4265 6.4.7. COPY Command 4267 Arguments: sequence set 4268 mailbox name 4270 Responses: no specific responses for this command 4272 Result: OK - copy completed 4273 NO - copy error: can't copy those messages or to that 4274 name 4275 BAD - command unknown or arguments invalid 4277 The COPY command copies the specified message(s) to the end of the 4278 specified destination mailbox. The flags and internal date of the 4279 message(s) SHOULD be preserved in the copy. 4281 If the destination mailbox does not exist, a server SHOULD return an 4282 error. It SHOULD NOT automatically create the mailbox. Unless it is 4283 certain that the destination mailbox can not be created, the server 4284 MUST send the response code "[TRYCREATE]" as the prefix of the text 4285 of the tagged NO response. This gives a hint to the client that it 4286 can attempt a CREATE command and retry the COPY if the CREATE is 4287 successful. 4289 If the COPY command is unsuccessful for any reason, server 4290 implementations MUST restore the destination mailbox to its state 4291 before the COPY attempt. 4293 On successful completion of a COPY, the server SHOULD return a 4294 COPYUID response code (see Section 7.1). 4296 In the case of a mailbox that has permissions set so that the client 4297 can COPY to the mailbox, but not SELECT or EXAMINE it, the server 4298 SHOULD NOT send an COPYUID response code as it would disclose 4299 information about the mailbox. 4301 In the case of a mailbox that has UIDNOTSTICKY status (see 4302 Section 7.1), the server MAY omit the COPYUID response code as it is 4303 not meaningful. 4305 If the server does not return the COPYUID response code, the client 4306 can discover this information by selecting the destination mailbox. 4308 The location of messages placed in the destination mailbox by COPY 4309 can be determined by using FETCH and/or SEARCH commands (e.g., for 4310 Message-ID). 4312 Example: C: A003 COPY 2:4 MEETING 4313 S: A003 OK COPY completed 4315 6.4.8. MOVE Command 4317 Arguments: sequence set 4318 mailbox name 4320 Responses: no specific responses for this command 4322 Result: OK - move completed 4323 NO - move error: can't move those messages or to that 4324 name 4325 BAD - command unknown or arguments invalid 4327 The MOVE command moves the specified message(s) to the end of the 4328 specified destination mailbox. The flags and internal date of the 4329 message(s) SHOULD be preserved. 4331 This means that a new message is created in the target mailbox with a 4332 new UID, the original message is removed from the source mailbox, and 4333 it appears to the client as a single action. This has the same 4334 effect for each message as this sequence: 4336 1. [UID] COPY 4338 2. [UID] STORE +FLAGS.SILENT \DELETED 4340 3. UID EXPUNGE 4342 Although the effect of the MOVE is the same as the preceding steps, 4343 the semantics are not identical: The intermediate states produced by 4344 those steps do not occur, and the response codes are different. In 4345 particular, though the COPY and EXPUNGE response codes will be 4346 returned, response codes for a STORE MUST NOT be generated and the 4347 \Deleted flag MUST NOT be set for any message. 4349 Because a MOVE applies to a set of messages, it might fail partway 4350 through the set. Regardless of whether the command is successful in 4351 moving the entire set, each individual message SHOULD either be moved 4352 or unaffected. The server MUST leave each message in a state where 4353 it is in at least one of the source or target mailboxes (no message 4354 can be lost or orphaned). The server SHOULD NOT leave any message in 4355 both mailboxes (it would be bad for a partial failure to result in a 4356 bunch of duplicate messages). This is true even if the server 4357 returns a tagged NO response to the command. 4359 Because of the similarity of MOVE to COPY, extensions that affect 4360 COPY affect MOVE in the same way. Response codes such as TRYCREATE 4361 (see Section 7.1), as well as those defined by extensions, are sent 4362 as appropriate. 4364 Servers SHOULD send COPYUID in response to a UID MOVE (see 4365 Section 6.4.9) command. For additional information see Section 7.1. 4367 Servers are also advised to send the COPYUID response code in an 4368 untagged OK before sending EXPUNGE or moved responses. (Sending 4369 COPYUID in the tagged OK, as described in the UIDPLUS specification, 4370 means that clients first receive an EXPUNGE for a message and 4371 afterwards COPYUID for the same message. It can be unnecessarily 4372 difficult to process that sequence usefully.) 4374 An example: 4375 C: a UID MOVE 42:69 foo 4376 S: * OK [COPYUID 432432 42:69 1202:1229] 4377 S: * 22 EXPUNGE 4378 S: (more expunges) 4379 S: a OK Done 4381 Note that the server may send unrelated EXPUNGE responses as well, if 4382 any happen to have been expunged at the same time; this is normal 4383 IMAP operation. 4385 Note that moving a message to the currently selected mailbox (that 4386 is, where the source and target mailboxes are the same) is allowed 4387 when copying the message to the currently selected mailbox is 4388 allowed. 4390 The server may send EXPUNGE responses before the tagged response, so 4391 the client cannot safely send more commands with message sequence 4392 number arguments while the server is processing MOVE. 4394 MOVE and UID MOVE can be pipelined with other commands, but care has 4395 to be taken. Both commands modify sequence numbers and also allow 4396 unrelated EXPUNGE responses. The renumbering of other messages in 4397 the source mailbox following any EXPUNGE response can be surprising 4398 and makes it unsafe to pipeline any command that relies on message 4399 sequence numbers after a MOVE or UID MOVE. Similarly, MOVE cannot be 4400 pipelined with a command that might cause message renumbering. See 4401 Section 5.5, for more information about ambiguities as well as 4402 handling requirements for both clients and servers. 4404 6.4.9. UID Command 4406 Arguments: command name 4407 command arguments 4409 Responses: untagged responses: FETCH, ESEARCH, EXPUNGE 4411 Result: OK - UID command completed 4412 NO - UID command error 4413 BAD - command unknown or arguments invalid 4415 The UID command has three forms. In the first form, it takes as its 4416 arguments a COPY, MOVE, FETCH, or STORE command with arguments 4417 appropriate for the associated command. However, the numbers in the 4418 sequence set argument are unique identifiers instead of message 4419 sequence numbers. Sequence set ranges are permitted, but there is no 4420 guarantee that unique identifiers will be contiguous. 4422 A non-existent unique identifier is ignored without any error message 4423 generated. Thus, it is possible for a UID FETCH command to return an 4424 OK without any data or a UID COPY, UID MOVE or UID STORE to return an 4425 OK without performing any operations. 4427 In the second form, the UID command takes an EXPUNGE command with an 4428 extra parameter the specified a sequence set of UIDs to operate on. 4429 The UID EXPUNGE command permanently removes all messages that both 4430 have the \Deleted flag set and have a UID that is included in the 4431 specified sequence set from the currently selected mailbox. If a 4432 message either does not have the \Deleted flag set or has a UID that 4433 is not included in the specified sequence set, it is not affected. 4435 UID EXPUNGE is particularly useful for disconnected use clients. 4436 By using UID EXPUNGE instead of EXPUNGE when resynchronizing with 4437 the server, the client can ensure that it does not inadvertantly 4438 remove any messages that have been marked as \Deleted by other 4439 clients between the time that the client was last connected and 4440 the time the client resynchronizes. 4442 Example: C: A003 UID EXPUNGE 3000:3002 4443 S: * 3 EXPUNGE 4444 S: * 3 EXPUNGE 4445 S: * 3 EXPUNGE 4446 S: A003 OK UID EXPUNGE completed 4448 In the third form, the UID command takes a SEARCH command with SEARCH 4449 command arguments. The interpretation of the arguments is the same 4450 as with SEARCH; however, the numbers returned in a ESEARCH response 4451 for a UID SEARCH command are unique identifiers instead of message 4452 sequence numbers. Also, the corresponding ESEARCH response MUST 4453 include the UID indicator. For example, the command UID SEARCH 1:100 4454 UID 443:557 returns the unique identifiers corresponding to the 4455 intersection of two sequence sets, the message sequence number range 4456 1:100 and the UID range 443:557. 4458 Note: in the above example, the UID range 443:557 appears. The 4459 same comment about a non-existent unique identifier being ignored 4460 without any error message also applies here. Hence, even if 4461 neither UID 443 or 557 exist, this range is valid and would 4462 include an existing UID 495. 4464 Also note that a UID range of 559:* always includes the UID of the 4465 last message in the mailbox, even if 559 is higher than any 4466 assigned UID value. This is because the contents of a range are 4467 independent of the order of the range endpoints. Thus, any UID 4468 range with * as one of the endpoints indicates at least one 4469 message (the message with the highest numbered UID), unless the 4470 mailbox is empty. 4472 The number after the "*" in an untagged FETCH or EXPUNGE response is 4473 always a message sequence number, not a unique identifier, even for a 4474 UID command response. However, server implementations MUST 4475 implicitly include the UID message data item as part of any FETCH 4476 response caused by a UID command, regardless of whether a UID was 4477 specified as a message data item to the FETCH. 4479 Note: The rule about including the UID message data item as part of a 4480 FETCH response primarily applies to the UID FETCH and UID STORE 4481 commands, including a UID FETCH command that does not include UID as 4482 a message data item. Although it is unlikely that the other UID 4483 commands will cause an untagged FETCH, this rule applies to these 4484 commands as well. 4486 Example: C: A999 UID FETCH 4827313:4828442 FLAGS 4487 S: * 23 FETCH (FLAGS (\Seen) UID 4827313) 4488 S: * 24 FETCH (FLAGS (\Seen) UID 4827943) 4489 S: * 25 FETCH (FLAGS (\Seen) UID 4828442) 4490 S: A999 OK UID FETCH completed 4492 6.5. Client Commands - Experimental/Expansion 4494 6.5.1. X Command 4496 Arguments: implementation defined 4498 Responses: implementation defined 4499 Result: OK - command completed 4500 NO - failure 4501 BAD - command unknown or arguments invalid 4503 Any command prefixed with an X is an experimental command. Commands 4504 which are not part of this specification, a standard or standards- 4505 track revision of this specification, or an IESG-approved 4506 experimental protocol, MUST use the X prefix. 4508 Any added untagged responses issued by an experimental command MUST 4509 also be prefixed with an X. Server implementations MUST NOT send any 4510 such untagged responses, unless the client requested it by issuing 4511 the associated experimental command. 4513 Example: C: a441 CAPABILITY 4514 S: * CAPABILITY IMAP4rev2 XPIG-LATIN 4515 S: a441 OK CAPABILITY completed 4516 C: A442 XPIG-LATIN 4517 S: * XPIG-LATIN ow-nay eaking-spay ig-pay atin-lay 4518 S: A442 OK XPIG-LATIN ompleted-cay 4520 7. Server Responses 4522 Server responses are in three forms: status responses, server data, 4523 and command continuation request. The information contained in a 4524 server response, identified by "Contents:" in the response 4525 descriptions below, is described by function, not by syntax. The 4526 precise syntax of server responses is described in the Formal Syntax 4527 section. 4529 The client MUST be prepared to accept any response at all times. 4531 Status responses can be tagged or untagged. Tagged status responses 4532 indicate the completion result (OK, NO, or BAD status) of a client 4533 command, and have a tag matching the command. 4535 Some status responses, and all server data, are untagged. An 4536 untagged response is indicated by the token "*" instead of a tag. 4537 Untagged status responses indicate server greeting, or server status 4538 that does not indicate the completion of a command (for example, an 4539 impending system shutdown alert). For historical reasons, untagged 4540 server data responses are also called "unsolicited data", although 4541 strictly speaking, only unilateral server data is truly 4542 "unsolicited". 4544 Certain server data MUST be recorded by the client when it is 4545 received; this is noted in the description of that data. Such data 4546 conveys critical information which affects the interpretation of all 4547 subsequent commands and responses (e.g., updates reflecting the 4548 creation or destruction of messages). 4550 Other server data SHOULD be recorded for later reference; if the 4551 client does not need to record the data, or if recording the data has 4552 no obvious purpose (e.g., a SEARCH response when no SEARCH command is 4553 in progress), the data SHOULD be ignored. 4555 An example of unilateral untagged server data occurs when the IMAP 4556 connection is in the selected state. In the selected state, the 4557 server checks the mailbox for new messages as part of command 4558 execution. Normally, this is part of the execution of every command; 4559 hence, a NOOP command suffices to check for new messages. If new 4560 messages are found, the server sends untagged EXISTS response 4561 reflecting the new size of the mailbox. Server implementations that 4562 offer multiple simultaneous access to the same mailbox SHOULD also 4563 send appropriate unilateral untagged FETCH and EXPUNGE responses if 4564 another agent changes the state of any message flags or expunges any 4565 messages. 4567 Command continuation request responses use the token "+" instead of a 4568 tag. These responses are sent by the server to indicate acceptance 4569 of an incomplete client command and readiness for the remainder of 4570 the command. 4572 7.1. Server Responses - Status Responses 4574 Status responses are OK, NO, BAD, PREAUTH and BYE. OK, NO, and BAD 4575 can be tagged or untagged. PREAUTH and BYE are always untagged. 4577 Status responses MAY include an OPTIONAL "response code". A response 4578 code consists of data inside square brackets in the form of an atom, 4579 possibly followed by a space and arguments. The response code 4580 contains additional information or status codes for client software 4581 beyond the OK/NO/BAD condition, and are defined when there is a 4582 specific action that a client can take based upon the additional 4583 information. 4585 The currently defined response codes are: 4587 ALERT 4589 The human-readable text contains a special alert that MUST be 4590 presented to the user in a fashion that calls the user's 4591 attention to the message. 4593 ALREADYEXISTS 4594 The operation attempts to create something that already exists, 4595 such as when the CREATE or RENAME directories attempt to create 4596 a mailbox and there is already one of that name. 4598 C: o356 RENAME this that 4599 S: o356 NO [ALREADYEXISTS] Mailbox "that" already exists 4601 APPENDUID 4603 Followed by the UIDVALIDITY of the destination mailbox and the 4604 UID assigned to the appended message in the destination 4605 mailbox, indicates that the message has been appended to the 4606 destination mailbox with that UID. 4608 If the server also supports the [MULTIAPPEND] extension, and if 4609 multiple messages were appended in the APPEND command, then the 4610 second value is a UID set containing the UIDs assigned to the 4611 appended messages, in the order they were transmitted in the 4612 APPEND command. This UID set may not contain extraneous UIDs 4613 or the symbol "*". 4615 Note: the UID set form of the APPENDUID response code MUST 4616 NOT be used if only a single message was appended. In 4617 particular, a server MUST NOT send a range such as 123:123. 4618 This is because a client that does not support [MULTIAPPEND] 4619 expects only a single UID and not a UID set. 4621 UIDs are assigned in strictly ascending order in the mailbox 4622 (refer to Section 2.3.1.1); note that a range of 12:10 is 4623 exactly equivalent to 10:12 and refers to the sequence 4624 10,11,12. 4626 This response code is returned in a tagged OK response to the 4627 APPEND command. 4629 AUTHENTICATIONFAILED 4631 Authentication failed for some reason on which the server is 4632 unwilling to elaborate. Typically, this includes "unknown 4633 user" and "bad password". 4635 This is the same as not sending any response code, except that 4636 when a client sees AUTHENTICATIONFAILED, it knows that the 4637 problem wasn't, e.g., UNAVAILABLE, so there's no point in 4638 trying the same login/password again later. 4640 C: b LOGIN "fred" "foo" 4641 S: b NO [AUTHENTICATIONFAILED] Authentication failed 4643 AUTHORIZATIONFAILED 4645 Authentication succeeded in using the authentication identity, 4646 but the server cannot or will not allow the authentication 4647 identity to act as the requested authorization identity. This 4648 is only applicable when the authentication and authorization 4649 identities are different. 4651 C: c1 AUTHENTICATE PLAIN 4652 [...] 4653 S: c1 NO [AUTHORIZATIONFAILED] No such authorization-ID 4655 C: c2 AUTHENTICATE PLAIN 4656 [...] 4657 S: c2 NO [AUTHORIZATIONFAILED] Authenticator is not an admin 4659 BADCHARSET 4661 Optionally followed by a parenthesized list of charsets. A 4662 SEARCH failed because the given charset is not supported by 4663 this implementation. If the optional list of charsets is 4664 given, this lists the charsets that are supported by this 4665 implementation. 4667 CANNOT 4669 The operation violates some invariant of the server and can 4670 never succeed. 4672 C: l create "///////" 4673 S: l NO [CANNOT] Adjacent slashes are not supported 4675 CAPABILITY 4677 Followed by a list of capabilities. This can appear in the 4678 initial OK or PREAUTH response to transmit an initial 4679 capabilities list. It can also appear in tagged responses to 4680 LOGIN or AUTHENTICATE commands. This makes it unnecessary for 4681 a client to send a separate CAPABILITY command if it recognizes 4682 this response. 4684 CLIENTBUG 4685 The server has detected a client bug. This can accompany all 4686 of OK, NO, and BAD, depending on what the client bug is. 4688 C: k1 select "/archive/projects/experiment-iv" 4689 [...] 4690 S: k1 OK [READ-ONLY] Done 4691 C: k2 status "/archive/projects/experiment-iv" (messages) 4692 [...] 4693 S: k2 OK [CLIENTBUG] Done 4695 CLOSED 4697 The CLOSED response code has no parameters. A server return 4698 the CLOSED response code when the currently selected mailbox is 4699 closed implicitly using the SELECT/EXAMINE command on another 4700 mailbox. The CLOSED response code serves as a boundary between 4701 responses for the previously opened mailbox (which was closed) 4702 and the newly selected mailbox; all responses before the CLOSED 4703 response code relate to the mailbox that was closed, and all 4704 subsequent responses relate to the newly opened mailbox. 4706 There is no need to return the CLOSED response code on 4707 completion of the CLOSE or the UNSELECT command (or similar), 4708 whose purpose is to close the currently selected mailbox 4709 without opening a new one. 4711 CONTACTADMIN 4713 The user should contact the system administrator or support 4714 desk. 4716 C: e login "fred" "foo" 4717 S: e OK [CONTACTADMIN] 4719 COPYUID 4721 Followed by the UIDVALIDITY of the destination mailbox, a UID 4722 set containing the UIDs of the message(s) in the source mailbox 4723 that were copied to the destination mailbox and containing the 4724 UIDs assigned to the copied message(s) in the destination 4725 mailbox, indicates that the message(s) have been copied to the 4726 destination mailbox with the stated UID(s). 4728 The source UID set is in the order the message(s) were copied; 4729 the destination UID set corresponds to the source UID set and 4730 is in the same order. Neither of the UID sets may contain 4731 extraneous UIDs or the symbol "*". 4733 UIDs are assigned in strictly ascending order in the mailbox 4734 (refer to Section 2.3.1.1); note that a range of 12:10 is 4735 exactly equivalent to 10:12 and refers to the sequence 4736 10,11,12. 4738 This response code is returned in a tagged OK response to the 4739 COPY command. 4741 CORRUPTION 4743 The server discovered that some relevant data (e.g., the 4744 mailbox) are corrupt. This response code does not include any 4745 information about what's corrupt, but the server can write that 4746 to its logfiles. 4748 C: i select "/archive/projects/experiment-iv" 4749 S: i NO [CORRUPTION] Cannot open mailbox 4751 EXPIRED 4753 Either authentication succeeded or the server no longer had the 4754 necessary data; either way, access is no longer permitted using 4755 that passphrase. The client or user should get a new 4756 passphrase. 4758 C: d login "fred" "foo" 4759 S: d NO [EXPIRED] That password isn't valid any more 4761 EXPUNGEISSUED 4763 Someone else has issued an EXPUNGE for the same mailbox. The 4764 client may want to issue NOOP soon. [IMAP-MULTIACCESS] 4765 discusses this subject in depth. 4767 C: h search from fred@example.com 4768 S: * ESEARCH (TAG "h") ALL 1:3,5,8,13,21,42 4769 S: h OK [EXPUNGEISSUED] Search completed 4771 HASCHILDREN 4773 The mailbox delete operation failed because the mailbox has one 4774 or more children and the server doesn't allow deletion of 4775 mailboxes with children. 4777 C: m356 DELETE Notes 4778 S: o356 NO [HASCHILDREN] Mailbox "Notes" has children that need 4779 to be deleted first 4781 INUSE 4783 An operation has not been carried out because it involves 4784 sawing off a branch someone else is sitting on. Someone else 4785 may be holding an exclusive lock needed for this operation, or 4786 the operation may involve deleting a resource someone else is 4787 using, typically a mailbox. 4789 The operation may succeed if the client tries again later. 4791 C: g delete "/archive/projects/experiment-iv" 4792 S: g NO [INUSE] Mailbox in use 4794 LIMIT 4796 The operation ran up against an implementation limit of some 4797 kind, such as the number of flags on a single message or the 4798 number of flags used in a mailbox. 4800 C: m STORE 42 FLAGS f1 f2 f3 f4 f5 ... f250 4801 S: m NO [LIMIT] At most 32 flags in one mailbox supported 4803 NONEXISTENT 4805 The operation attempts to delete something that does not exist. 4806 Similar to ALREADYEXISTS. 4808 C: p RENAME this that 4809 S: p NO [NONEXISTENT] No such mailbox 4811 NOPERM 4813 The access control system (e.g., Access Control List (ACL), see 4814 [RFC4314] does not permit this user to carry out an operation, 4815 such as selecting or creating a mailbox. 4817 C: f select "/archive/projects/experiment-iv" 4818 S: f NO [NOPERM] Access denied 4820 OVERQUOTA 4822 The user would be over quota after the operation. (The user 4823 may or may not be over quota already.) 4825 Note that if the server sends OVERQUOTA but doesn't support the 4826 IMAP QUOTA extension defined by [RFC2087], then there is a 4827 quota, but the client cannot find out what the quota is. 4829 C: n1 uid copy 1:* oldmail 4830 S: n1 NO [OVERQUOTA] Sorry 4832 C: n2 uid copy 1:* oldmail 4833 S: n2 OK [OVERQUOTA] You are now over your soft quota 4835 PARSE 4837 The human-readable text represents an error in parsing the 4838 [RFC-5322] header or [MIME-IMB] headers of a message in the 4839 mailbox. 4841 PERMANENTFLAGS 4843 Followed by a parenthesized list of flags, indicates which of 4844 the known flags the client can change permanently. Any flags 4845 that are in the FLAGS untagged response, but not the 4846 PERMANENTFLAGS list, can not be set permanently. The 4847 PERMANENTFLAGS list can also include the special flag \*, which 4848 indicates that it is possible to create new keywords by 4849 attempting to store those keywords in the mailbox. If the 4850 client attempts to STORE a flag that is not in the 4851 PERMANENTFLAGS list, the server will either ignore the change 4852 or store the state change for the remainder of the current 4853 session only. 4855 There is no need for a server that included the special flag \* 4856 to return a new PERMANENTFLAGS response code when a new keyword 4857 was successfully set on a message upon client request. However 4858 if the server has a limit on the number of different keywords 4859 that can be stored in a mailbox and that limit is reached, the 4860 server MUST send a new PERMANENTFLAGS response code without the 4861 special flag \*. 4863 PRIVACYREQUIRED 4865 The operation is not permitted due to a lack of privacy. If 4866 Transport Layer Security (TLS) is not in use, the client could 4867 try STARTTLS (see Section 6.2.1) and then repeat the operation. 4869 C: d login "fred" "foo" 4870 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4872 C: d select inbox 4873 S: d NO [PRIVACYREQUIRED] Connection offers no privacy 4875 READ-ONLY 4877 The mailbox is selected read-only, or its access while selected 4878 has changed from read-write to read-only. 4880 READ-WRITE 4882 The mailbox is selected read-write, or its access while 4883 selected has changed from read-only to read-write. 4885 SERVERBUG 4887 The server encountered a bug in itself or violated one of its 4888 own invariants. 4890 C: j select "/archive/projects/experiment-iv" 4891 S: j NO [SERVERBUG] This should not happen 4893 TRYCREATE 4895 An APPEND or COPY attempt is failing because the target mailbox 4896 does not exist (as opposed to some other reason). This is a 4897 hint to the client that the operation can succeed if the 4898 mailbox is first created by the CREATE command. 4900 UIDNEXT 4902 Followed by a decimal number, indicates the next unique 4903 identifier value. Refer to Section 2.3.1.1 for more 4904 information. 4906 UIDNOTSTICKY 4908 The selected mailbox is supported by a mail store that does not 4909 support persistent UIDs; that is, UIDVALIDITY will be different 4910 each time the mailbox is selected. Consequently, APPEND or 4911 COPY to this mailbox will not return an APPENDUID or COPYUID 4912 response code. 4914 This response code is returned in an untagged NO response to 4915 the SELECT command. 4917 Note: servers SHOULD NOT have any UIDNOTSTICKY mail stores. 4918 This facility exists to support legacy mail stores in which 4919 it is technically infeasible to support persistent UIDs. 4920 This should be avoided when designing new mail stores. 4922 UIDVALIDITY 4924 Followed by a decimal number, indicates the unique identifier 4925 validity value. Refer to Section 2.3.1.1 for more information. 4927 UNAVAILABLE 4929 Temporary failure because a subsystem is down. For example, an 4930 IMAP server that uses a Lightweight Directory Access Protocol 4931 (LDAP) or Radius server for authentication might use this 4932 response code when the LDAP/Radius server is down. 4934 C: a LOGIN "fred" "foo" 4935 S: a NO [UNAVAILABLE] User's backend down for maintenance 4937 UNKNOWN-CTE 4939 The server does not know how to decode the section's Content- 4940 Transfer-Encoding. 4942 Client implementations MUST ignore response codes that they do not 4943 recognize. 4945 7.1.1. OK Response 4947 Contents: OPTIONAL response code 4948 human-readable text 4950 The OK response indicates an information message from the server. 4951 When tagged, it indicates successful completion of the associated 4952 command. The human-readable text MAY be presented to the user as an 4953 information message. The untagged form indicates an information-only 4954 message; the nature of the information MAY be indicated by a response 4955 code. 4957 The untagged form is also used as one of three possible greetings at 4958 connection startup. It indicates that the connection is not yet 4959 authenticated and that a LOGIN or an AUTHENTICATE command is needed. 4961 Example: S: * OK IMAP4rev2 server ready 4962 C: A001 LOGIN fred blurdybloop 4963 S: * OK [ALERT] System shutdown in 10 minutes 4964 S: A001 OK LOGIN Completed 4966 7.1.2. NO Response 4968 Contents: OPTIONAL response code 4969 human-readable text 4971 The NO response indicates an operational error message from the 4972 server. When tagged, it indicates unsuccessful completion of the 4973 associated command. The untagged form indicates a warning; the 4974 command can still complete successfully. The human-readable text 4975 describes the condition. 4977 Example: C: A222 COPY 1:2 owatagusiam 4978 S: * NO Disk is 98% full, please delete unnecessary data 4979 S: A222 OK COPY completed 4980 C: A223 COPY 3:200 blurdybloop 4981 S: * NO Disk is 98% full, please delete unnecessary data 4982 S: * NO Disk is 99% full, please delete unnecessary data 4983 S: A223 NO COPY failed: disk is full 4985 7.1.3. BAD Response 4987 Contents: OPTIONAL response code 4988 human-readable text 4990 The BAD response indicates an error message from the server. When 4991 tagged, it reports a protocol-level error in the client's command; 4992 the tag indicates the command that caused the error. The untagged 4993 form indicates a protocol-level error for which the associated 4994 command can not be determined; it can also indicate an internal 4995 server failure. The human-readable text describes the condition. 4997 Example: C: ...very long command line... 4998 S: * BAD Command line too long 4999 C: ...empty line... 5000 S: * BAD Empty command line 5001 C: A443 EXPUNGE 5002 S: * BAD Disk crash, attempting salvage to a new disk! 5003 S: * OK Salvage successful, no data lost 5004 S: A443 OK Expunge completed 5006 7.1.4. PREAUTH Response 5008 Contents: OPTIONAL response code 5009 human-readable text 5011 The PREAUTH response is always untagged, and is one of three possible 5012 greetings at connection startup. It indicates that the connection 5013 has already been authenticated by external means; thus no LOGIN/ 5014 AUTHENTICATE command is needed. 5016 Example: S: * PREAUTH IMAP4rev2 server logged in as Smith 5018 7.1.5. BYE Response 5020 Contents: OPTIONAL response code 5021 human-readable text 5023 The BYE response is always untagged, and indicates that the server is 5024 about to close the connection. The human-readable text MAY be 5025 displayed to the user in a status report by the client. The BYE 5026 response is sent under one of four conditions: 5028 1. as part of a normal logout sequence. The server will close the 5029 connection after sending the tagged OK response to the LOGOUT 5030 command. 5032 2. as a panic shutdown announcement. The server closes the 5033 connection immediately. 5035 3. as an announcement of an inactivity autologout. The server 5036 closes the connection immediately. 5038 4. as one of three possible greetings at connection startup, 5039 indicating that the server is not willing to accept a connection 5040 from this client. The server closes the connection immediately. 5042 The difference between a BYE that occurs as part of a normal LOGOUT 5043 sequence (the first case) and a BYE that occurs because of a failure 5044 (the other three cases) is that the connection closes immediately in 5045 the failure case. In all cases the client SHOULD continue to read 5046 response data from the server until the connection is closed; this 5047 will ensure that any pending untagged or completion responses are 5048 read and processed. 5050 Example: S: * BYE Autologout; idle for too long 5052 7.2. Server Responses - Server and Mailbox Status 5054 These responses are always untagged. This is how server and mailbox 5055 status data are transmitted from the server to the client. Many of 5056 these responses typically result from a command with the same name. 5058 7.2.1. The ENABLED Response 5060 Contents: capability listing 5062 The ENABLED response occurs as a result of an ENABLE command. The 5063 capability listing contains a space-separated listing of capability 5064 names that the server supports and that were successfully enabled. 5065 The ENABLED response may contain no capabilities, which means that no 5066 extensions listed by the client were successfully enabled. 5068 7.2.2. CAPABILITY Response 5070 Contents: capability listing 5072 The CAPABILITY response occurs as a result of a CAPABILITY command. 5073 The capability listing contains a space-separated listing of 5074 capability names that the server supports. The capability listing 5075 MUST include the atom "IMAP4rev2". 5077 In addition, client and server implementations MUST implement the 5078 STARTTLS, LOGINDISABLED, and AUTH=PLAIN (described in [PLAIN]) 5079 capabilities. See the Security Considerations section for important 5080 information. 5082 A capability name which begins with "AUTH=" indicates that the server 5083 supports that particular authentication mechanism. 5085 The LOGINDISABLED capability indicates that the LOGIN command is 5086 disabled, and that the server will respond with a tagged NO response 5087 to any attempt to use the LOGIN command even if the user name and 5088 password are valid. An IMAP client MUST NOT issue the LOGIN command 5089 if the server advertises the LOGINDISABLED capability. 5091 Other capability names indicate that the server supports an 5092 extension, revision, or amendment to the IMAP4rev2 protocol. Server 5093 responses MUST conform to this document until the client issues a 5094 command that uses the associated capability. 5096 Capability names MUST either begin with "X" or be informational, 5097 experimental or standards-track IMAP4rev2 extensions, revisions, or 5098 amendments registered with IANA. A server SHOULD NOT offer 5099 unregistered or non-standard capability names, unless such names are 5100 prefixed with an "X". 5102 Client implementations SHOULD NOT require any capability name other 5103 than "IMAP4rev2", and MUST ignore any unknown capability names. 5105 A server MAY send capabilities automatically, by using the CAPABILITY 5106 response code in the initial PREAUTH or OK responses, and by sending 5107 an updated CAPABILITY response code in the tagged OK response as part 5108 of a successful authentication. It is unnecessary for a client to 5109 send a separate CAPABILITY command if it recognizes these automatic 5110 capabilities. 5112 Example: S: * CAPABILITY IMAP4rev2 STARTTLS AUTH=GSSAPI XPIG-LATIN 5114 7.2.3. LIST Response 5116 Contents: name attributes 5117 hierarchy delimiter 5118 name 5119 OPTIONAL extension data 5121 The LIST response occurs as a result of a LIST command. It returns a 5122 single name that matches the LIST specification. There can be 5123 multiple LIST responses for a single LIST command. 5125 The following base mailbox name attributes are defined: 5127 \NonExistent The "\NonExistent" attribute indicates that a mailbox 5128 name does not refer to an existing mailbox. Note that this 5129 attribute is not meaningful by itself, as mailbox names that match 5130 the canonical LIST pattern but don't exist must not be returned 5131 unless one of the two conditions listed below is also satisfied: 5133 1. The mailbox name also satisfies the selection criteria (for 5134 example, it is subscribed and the "SUBSCRIBED" selection 5135 option has been specified). 5137 2. "RECURSIVEMATCH" has been specified, and the mailbox name has 5138 at least one descendant mailbox name that does not match the 5139 LIST pattern and does match the selection criteria. 5141 In practice, this means that the "\NonExistent" attribute is 5142 usually returned with one or more of "\Subscribed", "\Remote", 5143 "\HasChildren", or the CHILDINFO extended data item. 5145 The "\NonExistent" attribute implies "\NoSelect". 5147 \Noinferiors It is not possible for any child levels of hierarchy to 5148 exist under this name; no child levels exist now and none can be 5149 created in the future. 5151 \Noselect It is not possible to use this name as a selectable 5152 mailbox. 5154 \HasChildren The presence of this attribute indicates that the 5155 mailbox has child mailboxes. A server SHOULD NOT set this 5156 attribute if there are child mailboxes and the user does not have 5157 permission to access any of them. In this case, \HasNoChildren 5158 SHOULD be used. In many cases, however, a server may not be able 5159 to efficiently compute whether a user has access to any child 5160 mailbox. Note that even though the \HasChildren attribute for a 5161 mailbox must be correct at the time of processing of the mailbox, 5162 a client must be prepared to deal with a situation when a mailbox 5163 is marked with the \HasChildren attribute, but no child mailbox 5164 appears in the response to the LIST command. This might happen, 5165 for example, due to children mailboxes being deleted or made 5166 inaccessible to the user (using access control) by another client 5167 before the server is able to list them. 5169 \HasNoChildren The presence of this attribute indicates that the 5170 mailbox has NO child mailboxes that are accessible to the 5171 currently authenticated user. 5173 \Marked The mailbox has been marked "interesting" by the server; the 5174 mailbox probably contains messages that have been added since the 5175 last time the mailbox was selected. 5177 \Unmarked The mailbox does not contain any additional messages since 5178 the last time the mailbox was selected. 5180 \Subscribed The mailbox name was subscribed to using the SUBSCRIBE 5181 command. 5183 \Remote The mailbox is a remote mailbox. 5185 It is an error for the server to return both a \HasChildren and a 5186 \HasNoChildren attribute in the same LIST response. A client that 5187 encounters a LIST response with both \HasChildren and \HasNoChildren 5188 attributes present should act as if both are absent in the LIST 5189 response. 5191 Note: the \HasNoChildren attribute should not be confused with the 5192 \NoInferiors attribute, which indicates that no child mailboxes 5193 exist now and none can be created in the future. 5195 If it is not feasible for the server to determine whether or not the 5196 mailbox is "interesting", the server SHOULD NOT send either \Marked 5197 or \Unmarked. The server MUST NOT send more than one of \Marked, 5198 \Unmarked, and \Noselect for a single mailbox, and MAY send none of 5199 these. 5201 In addition to the base mailbox name attributes defined above, an 5202 IMAP server MAY also include any or all of the following attributes 5203 that denote "role" (or "special-use") of a mailbox. These attributes 5204 are included along with base attributes defined above. A given 5205 mailbox may have none, one, or more than one of these attributes. In 5206 some cases, a special use is advice to a client about what to put in 5207 that mailbox. In other cases, it's advice to a client about what to 5208 expect to find there. 5210 \All This mailbox presents all messages in the user's message store. 5211 Implementations MAY omit some messages, such as, perhaps, those in 5212 \Trash and \Junk. When this special use is supported, it is 5213 almost certain to represent a virtual mailbox. 5215 \Archive This mailbox is used to archive messages. The meaning of 5216 an "archival" mailbox is server-dependent; typically, it will be 5217 used to get messages out of the inbox, or otherwise keep them out 5218 of the user's way, while still making them accessible. 5220 \Drafts This mailbox is used to hold draft messages -- typically, 5221 messages that are being composed but have not yet been sent. In 5222 some server implementations, this might be a virtual mailbox, 5223 containing messages from other mailboxes that are marked with the 5224 "\Draft" message flag. Alternatively, this might just be advice 5225 that a client put drafts here. 5227 \Flagged This mailbox presents all messages marked in some way as 5228 "important". When this special use is supported, it is likely to 5229 represent a virtual mailbox collecting messages (from other 5230 mailboxes) that are marked with the "\Flagged" message flag. 5232 \Junk This mailbox is where messages deemed to be junk mail are 5233 held. Some server implementations might put messages here 5234 automatically. Alternatively, this might just be advice to a 5235 client-side spam filter. 5237 \Sent This mailbox is used to hold copies of messages that have been 5238 sent. Some server implementations might put messages here 5239 automatically. Alternatively, this might just be advice that a 5240 client save sent messages here. 5242 \Trash This mailbox is used to hold messages that have been deleted 5243 or marked for deletion. In some server implementations, this 5244 might be a virtual mailbox, containing messages from other 5245 mailboxes that are marked with the "\Deleted" message flag. 5246 Alternatively, this might just be advice that a client that 5247 chooses not to use the IMAP "\Deleted" model should use this as 5248 its trash location. In server implementations that strictly 5249 expect the IMAP "\Deleted" model, this special use is likely not 5250 to be supported. 5252 All of special-use attributes are OPTIONAL, and any given server or 5253 message store may support any combination of the attributes, or none 5254 at all. In most cases, there will likely be at most one mailbox with 5255 a given attribute for a given user, but in some server or message 5256 store implementations it might be possible for multiple mailboxes to 5257 have the same special-use attribute. 5259 Special-use attributes are likely to be user-specific. User Adam 5260 might share his \Sent mailbox with user Barb, but that mailbox is 5261 unlikely to also serve as Barb's \Sent mailbox. 5263 Other mailbox name attributes can be found in the "IMAP Mailbox Name 5264 Attributes" registry [IMAP-MAILBOX-NAME-ATTRS-REG]. 5266 The hierarchy delimiter is a character used to delimit levels of 5267 hierarchy in a mailbox name. A client can use it to create child 5268 mailboxes, and to search higher or lower levels of naming hierarchy. 5269 All children of a top-level hierarchy node MUST use the same 5270 separator character. A NIL hierarchy delimiter means that no 5271 hierarchy exists; the name is a "flat" name. 5273 The name represents an unambiguous left-to-right hierarchy, and MUST 5274 be valid for use as a reference in LIST command. Unless \Noselect or 5275 \NonExistent is indicated, the name MUST also be valid as an argument 5276 for commands, such as SELECT, that accept mailbox names. 5278 The name might be followed by an OPTIONAL series of extended fields, 5279 a parenthesized list of tagged data (also referred to as "extended 5280 data item"). The first element of an extended field is a string, 5281 which identifies the type of data. [RFC5258] specified requirements 5282 on string registration (which are called "tags" there; such tags are 5283 not to be confused with IMAP command tags), in particular it said 5284 that "Tags MUST be registered with IANA". This document doesn't 5285 change that. See Section 9.5 of [RFC5258] for the registration 5286 template. The server MAY return data in the extended fields that was 5287 not directly solicited by the client in the corresponding LIST 5288 command. For example, the client can enable extra extended fields by 5289 using another IMAP extension that make use of the extended LIST 5290 responses. The client MUST ignore all extended fields it doesn't 5291 recognize. 5293 Example: S: * LIST (\Noselect) "/" ~/Mail/foo 5295 Example: S: * LIST (\Marked) ":" Tables (tablecloth (("edge" "lacy") 5296 ("color" "red")) Sample "text") 5297 S: * LIST () ":" Tables:new (tablecloth ("edge" "lacy") 5298 Sample ("text" "more text")) 5300 7.2.4. NAMESPACE Response 5302 Contents: the prefix and hierarchy delimiter to the server's 5303 Personal Namespace(s), Other Users' Namespace(s), and 5304 Shared Namespace(s) 5306 The NAMESPACE response occurs as a result of a NAMESPACE command. It 5307 contains the prefix and hierarchy delimiter to the server's Personal 5308 Namespace(s), Other Users' Namespace(s), and Shared Namespace(s) that 5309 the server wishes to expose. The response will contain a NIL for any 5310 namespace class that is not available. Namespace-Response-Extensions 5311 ABNF non terminal is defined for extensibility and MAY be included in 5312 the response. 5314 Example: S: * NAMESPACE (("" "/")) (("~" "/")) NIL 5316 7.2.5. STATUS Response 5318 Contents: name 5319 status parenthesized list 5321 The STATUS response occurs as a result of an STATUS command. It 5322 returns the mailbox name that matches the STATUS specification and 5323 the requested mailbox status information. 5325 Example: S: * STATUS blurdybloop (MESSAGES 231 UIDNEXT 44292) 5327 7.2.6. ESEARCH Response 5329 Contents: one or more search-return-data pairs 5331 The ESEARCH response occurs as a result of a SEARCH or UID SEARCH 5332 command. 5334 The ESEARCH response starts with an optional search correlator. If 5335 it is missing, then the response was not caused by a particular IMAP 5336 command, whereas if it is present, it contains the tag of the command 5337 that caused the response to be returned. 5339 The search correlator is followed by an optional UID indicator. If 5340 this indicator is present, all data in the ESEARCH response refers to 5341 UIDs, otherwise all returned data refers to message numbers. 5343 The rest of the ESEARCH response contains one or more search data 5344 pairs. Each pair starts with unique return item name, followed by a 5345 space and the corresponding data. Search data pairs may be returned 5346 in any order. Unless specified otherwise by an extension, any return 5347 item name SHOULD appear only once in an ESEARCH response. 5349 [[TBD: describe the most common search data pairs returned.]] 5351 Example: S: * ESEARCH UID COUNT 5 ALL 4:19,21,28 5353 Example: S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28 5355 Example: S: * ESEARCH COUNT 5 ALL 1:17,21 5357 7.2.7. FLAGS Response 5359 Contents: flag parenthesized list 5361 The FLAGS response occurs as a result of a SELECT or EXAMINE command. 5362 The flag parenthesized list identifies the flags (at a minimum, the 5363 system-defined flags) that are applicable for this mailbox. Flags 5364 other than the system flags can also exist, depending on server 5365 implementation. 5367 The update from the FLAGS response MUST be recorded by the client. 5369 Example: S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5371 7.3. Server Responses - Mailbox Size 5373 These responses are always untagged. This is how changes in the size 5374 of the mailbox are transmitted from the server to the client. 5375 Immediately following the "*" token is a number that represents a 5376 message count. 5378 7.3.1. EXISTS Response 5380 Contents: none 5382 The EXISTS response reports the number of messages in the mailbox. 5383 This response occurs as a result of a SELECT or EXAMINE command, and 5384 if the size of the mailbox changes (e.g., new messages). 5386 The update from the EXISTS response MUST be recorded by the client. 5388 Example: S: * 23 EXISTS 5390 7.4. Server Responses - Message Status 5392 These responses are always untagged. This is how message data are 5393 transmitted from the server to the client, often as a result of a 5394 command with the same name. Immediately following the "*" token is a 5395 number that represents a message sequence number. 5397 7.4.1. EXPUNGE Response 5399 Contents: none 5401 The EXPUNGE response reports that the specified message sequence 5402 number has been permanently removed from the mailbox. The message 5403 sequence number for each successive message in the mailbox is 5404 immediately decremented by 1, and this decrement is reflected in 5405 message sequence numbers in subsequent responses (including other 5406 untagged EXPUNGE responses). 5408 The EXPUNGE response also decrements the number of messages in the 5409 mailbox; it is not necessary to send an EXISTS response with the new 5410 value. 5412 As a result of the immediate decrement rule, message sequence numbers 5413 that appear in a set of successive EXPUNGE responses depend upon 5414 whether the messages are removed starting from lower numbers to 5415 higher numbers, or from higher numbers to lower numbers. For 5416 example, if the last 5 messages in a 9-message mailbox are expunged, 5417 a "lower to higher" server will send five untagged EXPUNGE responses 5418 for message sequence number 5, whereas a "higher to lower server" 5419 will send successive untagged EXPUNGE responses for message sequence 5420 numbers 9, 8, 7, 6, and 5. 5422 An EXPUNGE response MUST NOT be sent when no command is in progress, 5423 nor while responding to a FETCH, STORE, or SEARCH command. This rule 5424 is necessary to prevent a loss of synchronization of message sequence 5425 numbers between client and server. A command is not "in progress" 5426 until the complete command has been received; in particular, a 5427 command is not "in progress" during the negotiation of command 5428 continuation. 5430 Note: UID FETCH, UID STORE, and UID SEARCH are different commands 5431 from FETCH, STORE, and SEARCH. An EXPUNGE response MAY be sent 5432 during a UID command. 5434 The update from the EXPUNGE response MUST be recorded by the client. 5436 Example: S: * 44 EXPUNGE 5438 7.4.2. FETCH Response 5440 Contents: message data 5442 The FETCH response returns data about a message to the client. The 5443 data are pairs of data item names and their values in parentheses. 5444 This response occurs as the result of a FETCH or STORE command, as 5445 well as by unilateral server decision (e.g., flag updates). 5447 The current data items are: 5449 BINARY[]<> 5451 An or expressing the content of the 5452 specified section after removing any Content-Transfer-Encoding- 5453 related encoding. If is present it refers to the 5454 offset within the DECODED section data. 5456 If the domain of the decoded data is "8bit" and the data does 5457 not contain the NUL octet, the server SHOULD return the data in 5458 a instead of a ; this allows the client to 5459 determine if the "8bit" data contains the NUL octet without 5460 having to explicitly scan the data stream for for NULs. 5462 Messaging clients and servers have been notoriously lax in 5463 their adherence to the Internet CRLF convention for terminating 5464 lines of textual data (text/* media types) in Internet 5465 protocols. When sending data in BINARY[...] FETCH data item, 5466 servers MUST ensure that textual line-oriented sections are 5467 always transmitted using the IMAP4 CRLF line termination 5468 syntax, regardless of the underlying storage representation of 5469 the data on the server. 5471 If the server does not know how to decode the section's 5472 Content-Transfer-Encoding, it MUST fail the request and issue a 5473 "NO" response that contains the "UNKNOWN-CTE" response code. 5475 BINARY.SIZE[] 5477 The size of the section after removing any Content-Transfer- 5478 Encoding-related encoding. The value returned MUST match the 5479 size of the or that will be returned by 5480 the corresponding FETCH BINARY request. 5482 If the server does not know how to decode the section's 5483 Content-Transfer-Encoding, it MUST fail the request and issue a 5484 "NO" response that contains the "UNKNOWN-CTE" response code. 5486 BODY A form of BODYSTRUCTURE without extension data. 5488 BODY[
]<> 5490 A string expressing the body contents of the specified section. 5491 The string SHOULD be interpreted by the client according to the 5492 content transfer encoding, body type, and subtype. 5494 If the origin octet is specified, this string is a substring of 5495 the entire body contents, starting at that origin octet. This 5496 means that BODY[]<0> MAY be truncated, but BODY[] is NEVER 5497 truncated. 5499 Note: The origin octet facility MUST NOT be used by a server 5500 in a FETCH response unless the client specifically requested 5501 it by means of a FETCH of a BODY[
]<> data 5502 item. 5504 8-bit textual data is permitted if a [CHARSET] identifier is 5505 part of the body parameter parenthesized list for this section. 5506 Note that headers (part specifiers HEADER or MIME, or the 5507 header portion of a MESSAGE/RFC822 or MESSAGE/GLOBAL part), MAY 5508 be in UTF-8. Note also that the [RFC-5322] delimiting blank 5509 line between the header and the body is not affected by header 5510 line subsetting; the blank line is always included as part of 5511 header data, except in the case of a message which has no body 5512 and no blank line. 5514 Non-textual data such as binary data MUST be transfer encoded 5515 into a textual form, such as BASE64, prior to being sent to the 5516 client. To derive the original binary data, the client MUST 5517 decode the transfer encoded string. 5519 BODYSTRUCTURE 5521 A parenthesized list that describes the [MIME-IMB] body 5522 structure of a message. This is computed by the server by 5523 parsing the [MIME-IMB] header fields, defaulting various fields 5524 as necessary. 5526 For example, a simple text message of 48 lines and 2279 octets 5527 can have a body structure of: ("TEXT" "PLAIN" ("CHARSET" "US- 5528 ASCII") NIL NIL "7BIT" 2279 48) 5530 Multiple parts are indicated by parenthesis nesting. Instead 5531 of a body type as the first element of the parenthesized list, 5532 there is a sequence of one or more nested body structures. The 5533 second element of the parenthesized list is the multipart 5534 subtype (mixed, digest, parallel, alternative, etc.). 5536 For example, a two part message consisting of a text and a 5537 BASE64-encoded text attachment can have a body structure of: 5538 (("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 1152 5539 23)("TEXT" "PLAIN" ("CHARSET" "US-ASCII" "NAME" "cc.diff") 5540 "<960723163407.20117h@cac.washington.edu>" "Compiler diff" 5541 "BASE64" 4554 73) "MIXED") 5543 Extension data follows the multipart subtype. Extension data 5544 is never returned with the BODY fetch, but can be returned with 5545 a BODYSTRUCTURE fetch. Extension data, if present, MUST be in 5546 the defined order. The extension data of a multipart body part 5547 are in the following order: 5549 body parameter parenthesized list A parenthesized list of 5550 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5551 "bar" is the value of "foo", and "rag" is the value of 5552 "baz"] as defined in [MIME-IMB]. Servers SHOULD decode 5553 parameter value continuations and parameter value character 5554 sets as described in [RFC2231], for example, if the message 5555 contains parameters "baz*0", "baz*1" and "baz*2", the server 5556 should RFC2231-decode them, concatenate and return the 5557 resulting value as a parameter "baz". Similarly, if the 5558 message contains parameters "foo*0*" and "foo*1*", the 5559 server should RFC2231-decode them, convert to UTF-8, 5560 concatenate and return the resulting value as a parameter 5561 "foo*". 5563 body disposition A parenthesized list, consisting of a 5564 disposition type string, followed by a parenthesized list of 5565 disposition attribute/value pairs as defined in 5566 [DISPOSITION]. Servers SHOULD decode parameter value 5567 continuations as described in [RFC2231]. 5569 body language A string or parenthesized list giving the body 5570 language value as defined in [LANGUAGE-TAGS]. 5572 body location A string giving the body content URI as defined 5573 in [LOCATION]. 5575 Any following extension data are not yet defined in this 5576 version of the protocol. Such extension data can consist of 5577 zero or more NILs, strings, numbers, or potentially nested 5578 parenthesized lists of such data. Client implementations that 5579 do a BODYSTRUCTURE fetch MUST be prepared to accept such 5580 extension data. Server implementations MUST NOT send such 5581 extension data until it has been defined by a revision of this 5582 protocol. 5584 The basic fields of a non-multipart body part are in the 5585 following order: 5587 body type A string giving the content media type name as 5588 defined in [MIME-IMB]. 5590 body subtype A string giving the content subtype name as 5591 defined in [MIME-IMB]. 5593 body parameter parenthesized list A parenthesized list of 5594 attribute/value pairs [e.g., ("foo" "bar" "baz" "rag") where 5595 "bar" is the value of "foo" and "rag" is the value of "baz"] 5596 as defined in [MIME-IMB]. 5598 body id A string giving the Content-ID header field value as 5599 defined in Section 7 of [MIME-IMB]. 5601 body description A string giving the Content-Description 5602 header field value as defined in Section 8 of [MIME-IMB]. 5604 body encoding A string giving the content transfer encoding as 5605 defined in Section 6 of [MIME-IMB]. 5607 body size A number giving the size of the body in octets. 5608 Note that this size is the size in its transfer encoding and 5609 not the resulting size after any decoding. 5611 A body type of type MESSAGE and subtype RFC822 contains, 5612 immediately after the basic fields, the envelope structure, 5613 body structure, and size in text lines of the encapsulated 5614 message. 5616 A body type of type TEXT contains, immediately after the basic 5617 fields, the size of the body in text lines. Note that this 5618 size is the size in its content transfer encoding and not the 5619 resulting size after any decoding. 5621 Extension data follows the basic fields and the type-specific 5622 fields listed above. Extension data is never returned with the 5623 BODY fetch, but can be returned with a BODYSTRUCTURE fetch. 5624 Extension data, if present, MUST be in the defined order. 5626 The extension data of a non-multipart body part are in the 5627 following order: 5629 body MD5 A string giving the body MD5 value as defined in 5630 [MD5]. 5632 body disposition A parenthesized list with the same content 5633 and function as the body disposition for a multipart body 5634 part. 5636 body language A string or parenthesized list giving the body 5637 language value as defined in [LANGUAGE-TAGS]. 5639 body location A string giving the body content URI as defined 5640 in [LOCATION]. 5642 Any following extension data are not yet defined in this 5643 version of the protocol, and would be as described above under 5644 multipart extension data. 5646 ENVELOPE 5648 A parenthesized list that describes the envelope structure of a 5649 message. This is computed by the server by parsing the 5650 [RFC-5322] header into the component parts, defaulting various 5651 fields as necessary. 5653 The fields of the envelope structure are in the following 5654 order: date, subject, from, sender, reply-to, to, cc, bcc, in- 5655 reply-to, and message-id. The date, subject, in-reply-to, and 5656 message-id fields are strings. The from, sender, reply-to, to, 5657 cc, and bcc fields are parenthesized lists of address 5658 structures. 5660 An address structure is a parenthesized list that describes an 5661 electronic mail address. The fields of an address structure 5662 are in the following order: personal name, [SMTP] at-domain- 5663 list (source route, obs-route), mailbox name, and host name. 5665 [RFC-5322] group syntax is indicated by a special form of 5666 address structure in which the host name field is NIL. If the 5667 mailbox name field is also NIL, this is an end of group marker 5668 (semi-colon in RFC 822 syntax). If the mailbox name field is 5669 non-NIL, this is a start of group marker, and the mailbox name 5670 field holds the group name phrase. 5672 If the Date, Subject, In-Reply-To, and Message-ID header lines 5673 are absent in the [RFC-5322] header, the corresponding member 5674 of the envelope is NIL; if these header lines are present but 5675 empty the corresponding member of the envelope is the empty 5676 string. 5678 Note: some servers may return a NIL envelope member in the 5679 "present but empty" case. Clients SHOULD treat NIL and 5680 empty string as identical. 5682 Note: [RFC-5322] requires that all messages have a valid 5683 Date header. Therefore, for a well-formed message the date 5684 member in the envelope can not be NIL or the empty string. 5685 However it can be NIL for a malformed or a draft message. 5687 Note: [RFC-5322] requires that the In-Reply-To and Message- 5688 ID headers, if present, have non-empty content. Therefore, 5689 for a well-formed message the in-reply-to and message-id 5690 members in the envelope can not be the empty string. 5691 However they can still be the empty string for a malformed 5692 message. 5694 If the From, To, Cc, and Bcc header lines are absent in the 5695 [RFC-5322] header, or are present but empty, the corresponding 5696 member of the envelope is NIL. 5698 If the Sender or Reply-To lines are absent in the [RFC-5322] 5699 header, or are present but empty, the server sets the 5700 corresponding member of the envelope to be the same value as 5701 the from member (the client is not expected to know to do 5702 this). 5704 Note: [RFC-5322] requires that all messages have a valid 5705 From header. Therefore, for a well-formed message the from, 5706 sender, and reply-to members in the envelope can not be NIL. 5707 However they can be NIL for a malformed or a draft message. 5709 FLAGS A parenthesized list of flags that are set for this message. 5711 INTERNALDATE A string representing the internal date of the message. 5713 RFC822.SIZE A number expressing the [RFC-5322] size of the message. 5715 UID A number expressing the unique identifier of the message. 5717 If the server chooses to send unsolicited FETCH responses, they MUST 5718 include UID FETCH item. Note that this is a new requirement when 5719 compared to RFC 3501. 5721 Example: S: * 23 FETCH (FLAGS (\Seen) RFC822.SIZE 44827) 5723 7.5. Server Responses - Command Continuation Request 5725 The command continuation request response is indicated by a "+" token 5726 instead of a tag. This form of response indicates that the server is 5727 ready to accept the continuation of a command from the client. The 5728 remainder of this response is a line of text. 5730 This response is used in the AUTHENTICATE command to transmit server 5731 data to the client, and request additional client data. This 5732 response is also used if an argument to any command is a 5733 synchronizing literal. 5735 The client is not permitted to send the octets of the synchronizing 5736 literal unless the server indicates that it is expected. This 5737 permits the server to process commands and reject errors on a line- 5738 by-line basis. The remainder of the command, including the CRLF that 5739 terminates a command, follows the octets of the literal. If there 5740 are any additional command arguments, the literal octets are followed 5741 by a space and those arguments. 5743 Example: C: A001 LOGIN {11} 5744 S: + Ready for additional command text 5745 C: FRED FOOBAR {7} 5746 S: + Ready for additional command text 5747 C: fat man 5748 S: A001 OK LOGIN completed 5749 C: A044 BLURDYBLOOP {102856} 5750 S: A044 BAD No such command as "BLURDYBLOOP" 5752 8. Sample IMAP4rev2 connection 5754 The following is a transcript of an IMAP4rev2 connection. A long 5755 line in this sample is broken for editorial clarity. 5757 S: * OK IMAP4rev2 Service Ready 5758 C: a001 login mrc secret 5759 S: a001 OK LOGIN completed 5760 C: a002 select inbox 5761 S: * 18 EXISTS 5762 S: * FLAGS (\Answered \Flagged \Deleted \Seen \Draft) 5763 S: * OK [UIDVALIDITY 3857529045] UIDs valid 5764 S: * LIST () "/" INBOX ("OLDNAME" ("inbox")) 5765 S: a002 OK [READ-WRITE] SELECT completed 5766 C: a003 fetch 12 full 5767 S: * 12 FETCH (FLAGS (\Seen) INTERNALDATE "17-Jul-1996 02:44:25 -0700" 5768 RFC822.SIZE 4286 ENVELOPE ("Wed, 17 Jul 1996 02:23:25 -0700 (PDT)" 5769 "IMAP4rev2 WG mtg summary and minutes" 5770 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5771 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5772 (("Terry Gray" NIL "gray" "cac.washington.edu")) 5773 ((NIL NIL "imap" "cac.washington.edu")) 5774 ((NIL NIL "minutes" "CNRI.Reston.VA.US") 5775 ("John Klensin" NIL "KLENSIN" "MIT.EDU")) NIL NIL 5776 "") 5777 BODY ("TEXT" "PLAIN" ("CHARSET" "US-ASCII") NIL NIL "7BIT" 3028 5778 92)) 5779 S: a003 OK FETCH completed 5780 C: a004 fetch 12 body[header] 5781 S: * 12 FETCH (BODY[HEADER] {342} 5782 S: Date: Wed, 17 Jul 1996 02:23:25 -0700 (PDT) 5783 S: From: Terry Gray 5784 S: Subject: IMAP4rev2 WG mtg summary and minutes 5785 S: To: imap@cac.washington.edu 5786 S: cc: minutes@CNRI.Reston.VA.US, John Klensin 5787 S: Message-Id: 5788 S: MIME-Version: 1.0 5789 S: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII 5790 S: 5791 S: ) 5792 S: a004 OK FETCH completed 5793 C: a005 store 12 +flags \deleted 5794 S: * 12 FETCH (FLAGS (\Seen \Deleted)) 5795 S: a005 OK +FLAGS completed 5796 C: a006 logout 5797 S: * BYE IMAP4rev2 server terminating connection 5798 S: a006 OK LOGOUT completed 5800 9. Formal Syntax 5802 The following syntax specification uses the Augmented Backus-Naur 5803 Form (ABNF) notation as specified in [ABNF]. 5805 In the case of alternative or optional rules in which a later rule 5806 overlaps an earlier rule, the rule which is listed earlier MUST take 5807 priority. For example, "\Seen" when parsed as a flag is the \Seen 5808 flag name and not a flag-extension, even though "\Seen" can be parsed 5809 as a flag-extension. Some, but not all, instances of this rule are 5810 noted below. 5812 Note: [ABNF] rules MUST be followed strictly; in particular: 5814 (1) Except as noted otherwise, all alphabetic characters are case- 5815 insensitive. The use of upper or lower case characters to define 5816 token strings is for editorial clarity only. Implementations MUST 5817 accept these strings in a case-insensitive fashion. 5819 (2) In all cases, SP refers to exactly one space. It is NOT 5820 permitted to substitute TAB, insert additional spaces, or 5821 otherwise treat SP as being equivalent to LWSP. 5823 (3) The ASCII NUL character, %x00, MUST NOT be used at any time. 5825 address = "(" addr-name SP addr-adl SP addr-mailbox SP 5826 addr-host ")" 5828 addr-adl = nstring 5829 ; Holds route from [RFC-5322] obs-route if 5830 ; non-NIL 5832 addr-host = nstring 5833 ; NIL indicates [RFC-5322] group syntax. 5834 ; Otherwise, holds [RFC-5322] domain name 5836 addr-mailbox = nstring 5837 ; NIL indicates end of [RFC-5322] group; if 5838 ; non-NIL and addr-host is NIL, holds 5839 ; [RFC-5322] group name. 5840 ; Otherwise, holds [RFC-5322] local-part 5841 ; after removing [RFC-5322] quoting 5843 addr-name = nstring 5844 ; If non-NIL, holds phrase from [RFC-5322] 5845 ; mailbox after removing [RFC-5322] quoting 5847 append = "APPEND" SP mailbox [SP flag-list] [SP date-time] SP 5848 literal 5850 append-uid = uniqueid 5852 astring = 1*ASTRING-CHAR / string 5853 ASTRING-CHAR = ATOM-CHAR / resp-specials 5855 atom = 1*ATOM-CHAR 5857 ATOM-CHAR = 5859 atom-specials = "(" / ")" / "{" / SP / CTL / list-wildcards / 5860 quoted-specials / resp-specials 5862 authenticate = "AUTHENTICATE" SP auth-type [SP initial-resp] 5863 *(CRLF base64) 5865 auth-type = atom 5866 ; Defined by [SASL] 5868 base64 = *(4base64-char) [base64-terminal] 5870 base64-char = ALPHA / DIGIT / "+" / "/" 5871 ; Case-sensitive 5873 base64-terminal = (2base64-char "==") / (3base64-char "=") 5875 body = "(" (body-type-1part / body-type-mpart) ")" 5877 body-extension = nstring / number / 5878 "(" body-extension *(SP body-extension) ")" 5879 ; Future expansion. Client implementations 5880 ; MUST accept body-extension fields. Server 5881 ; implementations MUST NOT generate 5882 ; body-extension fields except as defined by 5883 ; future standard or standards-track 5884 ; revisions of this specification. 5886 body-ext-1part = body-fld-md5 [SP body-fld-dsp [SP body-fld-lang 5887 [SP body-fld-loc *(SP body-extension)]]] 5888 ; MUST NOT be returned on non-extensible 5889 ; "BODY" fetch 5891 body-ext-mpart = body-fld-param [SP body-fld-dsp [SP body-fld-lang 5892 [SP body-fld-loc *(SP body-extension)]]] 5893 ; MUST NOT be returned on non-extensible 5894 ; "BODY" fetch 5896 body-fields = body-fld-param SP body-fld-id SP body-fld-desc SP 5897 body-fld-enc SP body-fld-octets 5899 body-fld-desc = nstring 5900 body-fld-dsp = "(" string SP body-fld-param ")" / nil 5902 body-fld-enc = (DQUOTE ("7BIT" / "8BIT" / "BINARY" / "BASE64"/ 5903 "QUOTED-PRINTABLE") DQUOTE) / string 5904 ; Content-Transfer-Encoding header field value. 5905 ; Defaults to "7BIT" (as per RFC 2045) 5906 ; if not present in the body part. 5908 body-fld-id = nstring 5910 body-fld-lang = nstring / "(" string *(SP string) ")" 5912 body-fld-loc = nstring 5914 body-fld-lines = number 5916 body-fld-md5 = nstring 5918 body-fld-octets = number 5920 body-fld-param = "(" string SP string *(SP string SP string) ")" / nil 5922 body-type-1part = (body-type-basic / body-type-msg / body-type-text) 5923 [SP body-ext-1part] 5925 body-type-basic = media-basic SP body-fields 5926 ; MESSAGE subtype MUST NOT be "RFC822" or "GLOBAL" 5928 body-type-mpart = 1*body SP media-subtype 5929 [SP body-ext-mpart] 5930 ; MULTIPART body part 5932 body-type-msg = media-message SP body-fields SP envelope 5933 SP body SP body-fld-lines 5935 body-type-text = media-text SP body-fields SP body-fld-lines 5937 capability = ("AUTH=" auth-type) / atom 5938 ; New capabilities MUST begin with "X" or be 5939 ; registered with IANA in 5940 ; a standards-track, an experimental 5941 ; or an informational RFC. 5943 capability-data = "CAPABILITY" *(SP capability) SP "IMAP4rev2" 5944 *(SP capability) 5945 ; Servers MUST implement the STARTTLS, AUTH=PLAIN, 5946 ; and LOGINDISABLED capabilities. 5947 ; Servers which offer RFC 1730 compatibility MUST 5948 ; list "IMAP4" as the first capability. 5949 ; Servers which offer RFC 3501 compatibility MUST 5950 ; list "IMAP4rev1" as one of capabilities. 5952 CHAR = 5954 CHAR8 = %x01-ff 5955 ; any OCTET except NUL, %x00 5957 charset = atom / quoted 5959 childinfo-extended-item = "CHILDINFO" SP "(" 5960 list-select-base-opt-quoted 5961 *(SP list-select-base-opt-quoted) ")" 5962 ; Extended data item (mbox-list-extended-item) 5963 ; returned when the RECURSIVEMATCH 5964 ; selection option is specified. 5965 ; Note 1: the CHILDINFO extended data item tag can be 5966 ; returned with and without surrounding quotes, as per 5967 ; mbox-list-extended-item-tag production. 5968 ; Note 2: The selection options are always returned 5969 ; quoted, unlike their specification in 5970 ; the extended LIST command. 5972 child-mbox-flag = "\HasChildren" / "\HasNoChildren" 5973 ; attributes for CHILDREN return option, at most one 5974 ; possible per LIST response 5976 command = tag SP (command-any / command-auth / command-nonauth / 5977 command-select) CRLF 5978 ; Modal based on state 5980 command-any = "CAPABILITY" / "LOGOUT" / "NOOP" / enable / x-command 5981 ; Valid in all states 5983 command-auth = append / create / delete / examine / list / 5984 Namespace-Command / 5985 rename / select / status / subscribe / unsubscribe / 5986 idle 5987 ; Valid only in Authenticated or Selected state 5989 command-nonauth = login / authenticate / "STARTTLS" 5990 ; Valid only when in Not Authenticated state 5992 command-select = "CLOSE" / "UNSELECT" / "EXPUNGE" / copy / 5993 move / fetch / store / search / uid 5994 ; Valid only when in Selected state 5996 continue-req = "+" SP (resp-text / base64) CRLF 5998 copy = "COPY" SP sequence-set SP mailbox 6000 create = "CREATE" SP mailbox 6001 ; Use of INBOX gives a NO error 6003 date = date-text / DQUOTE date-text DQUOTE 6005 date-day = 1*2DIGIT 6006 ; Day of month 6008 date-day-fixed = (SP DIGIT) / 2DIGIT 6009 ; Fixed-format version of date-day 6011 date-month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / 6012 "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" 6014 date-text = date-day "-" date-month "-" date-year 6016 date-year = 4DIGIT 6018 date-time = DQUOTE date-day-fixed "-" date-month "-" date-year 6019 SP time SP zone DQUOTE 6021 delete = "DELETE" SP mailbox 6022 ; Use of INBOX gives a NO error 6024 digit-nz = %x31-39 6025 ; 1-9 6027 eitem-standard-tag = atom 6028 ; a tag for LIST extended data item defined in a Standard 6029 ; Track or Experimental RFC. 6031 eitem-vendor-tag = vendor-token "-" atom 6032 ; a vendor-specific tag for LIST extended data item 6034 enable = "ENABLE" 1*(SP capability) 6036 enable-data = "ENABLED" *(SP capability) 6038 envelope = "(" env-date SP env-subject SP env-from SP 6039 env-sender SP env-reply-to SP env-to SP env-cc SP 6040 env-bcc SP env-in-reply-to SP env-message-id ")" 6042 env-bcc = "(" 1*address ")" / nil 6043 env-cc = "(" 1*address ")" / nil 6045 env-date = nstring 6047 env-from = "(" 1*address ")" / nil 6049 env-in-reply-to = nstring 6051 env-message-id = nstring 6053 env-reply-to = "(" 1*address ")" / nil 6055 env-sender = "(" 1*address ")" / nil 6057 env-subject = nstring 6059 env-to = "(" 1*address ")" / nil 6061 esearch-response = "ESEARCH" [search-correlator] [SP "UID"] 6062 *(SP search-return-data) 6063 ; ESEARCH response replaces SEARCH response 6064 ; from IMAP4rev1. 6066 examine = "EXAMINE" SP mailbox 6068 fetch = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" / 6069 fetch-att / "(" fetch-att *(SP fetch-att) ")") 6071 fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" / 6072 "RFC822.SIZE" / 6073 "BODY" ["STRUCTURE"] / "UID" / 6074 "BODY" section [partial] / 6075 "BODY.PEEK" section [partial] / 6076 "BINARY" [".PEEK"] section-binary [partial] / 6077 "BINARY.SIZE" section-binary 6079 flag = "\Answered" / "\Flagged" / "\Deleted" / 6080 "\Seen" / "\Draft" / flag-keyword / flag-extension 6081 ; Does not include "\Recent" 6083 flag-extension = "\" atom 6084 ; Future expansion. Client implementations 6085 ; MUST accept flag-extension flags. Server 6086 ; implementations MUST NOT generate 6087 ; flag-extension flags except as defined by 6088 ; future standard or standards-track 6089 ; revisions of this specification. 6090 ; "\Recent" was defined in RFC 3501 6091 ; and is now deprecated. 6093 flag-fetch = flag 6095 flag-keyword = "$MDNSent" / "$Forwarded" / "$Junk" / 6096 "$NotJunk" / "$Phishing" / atom 6098 flag-list = "(" [flag *(SP flag)] ")" 6100 flag-perm = flag / "\*" 6102 greeting = "*" SP (resp-cond-auth / resp-cond-bye) CRLF 6104 header-fld-name = astring 6106 header-list = "(" header-fld-name *(SP header-fld-name) ")" 6108 idle = "IDLE" CRLF "DONE" 6110 initial-resp = (base64 / "=") 6111 ; "initial response" defined in 6112 ; Section 5.1 of [RFC4422] 6114 list = "LIST" [SP list-select-opts] SP mailbox SP mbox-or-pat 6115 [SP list-return-opts] 6117 list-mailbox = 1*list-char / string 6119 list-char = ATOM-CHAR / list-wildcards / resp-specials 6121 list-return-opts = "RETURN" SP 6122 "(" [return-option *(SP return-option)] ")" 6123 ; list return options, e.g., CHILDREN 6125 list-select-base-opt = "SUBSCRIBED" / option-extension 6126 ; options that can be used by themselves 6128 list-select-base-opt-quoted = DQUOTE list-select-base-opt DQUOTE 6130 list-select-independent-opt = "REMOTE" / option-extension 6131 ; options that do not syntactically interact with 6132 ; other options 6134 list-select-mod-opt = "RECURSIVEMATCH" / option-extension 6135 ; options that require a list-select-base-opt 6136 ; to also be present 6138 list-select-opt = list-select-base-opt / list-select-independent-opt 6139 / list-select-mod-opt 6140 ; An option registration template is described in 6141 ; Section 9.3 of this document. 6143 list-select-opts = "(" [ 6144 (*(list-select-opt SP) list-select-base-opt 6145 *(SP list-select-opt)) 6146 / (list-select-independent-opt 6147 *(SP list-select-independent-opt)) 6148 ] ")" 6149 ; Any number of options may be in any order. 6150 ; If a list-select-mod-opt appears, then a 6151 ; list-select-base-opt must also appear. 6152 ; This allows these: 6153 ; () 6154 ; (REMOTE) 6155 ; (SUBSCRIBED) 6156 ; (SUBSCRIBED REMOTE) 6157 ; (SUBSCRIBED RECURSIVEMATCH) 6158 ; (SUBSCRIBED REMOTE RECURSIVEMATCH) 6159 ; But does NOT allow these: 6160 ; (RECURSIVEMATCH) 6161 ; (REMOTE RECURSIVEMATCH) 6163 list-wildcards = "%" / "*" 6165 literal = "{" number ["+"] "}" CRLF *CHAR8 6166 ; represents the number of CHAR8s. 6167 ; A non-synchronizing literal is distinguished from 6168 ; a synchronizing literal by presence of the "+" 6169 ; before the closing "}". 6170 ; Non synchronizing literals are not allowed when 6171 ; sent from server to the client. 6173 literal8 = "~{" number "}" CRLF *OCTET 6174 ; represents the number of OCTETs 6175 ; in the response string. 6177 login = "LOGIN" SP userid SP password 6179 mailbox = "INBOX" / astring 6180 ; INBOX is case-insensitive. All case variants of 6181 ; INBOX (e.g., "iNbOx") MUST be interpreted as INBOX 6182 ; not as an astring. An astring which consists of 6183 ; the case-insensitive sequence "I" "N" "B" "O" "X" 6184 ; is considered to be INBOX and not an astring. 6185 ; Refer to section 5.1 for further 6186 ; semantic details of mailbox names. 6188 mailbox-data = "FLAGS" SP flag-list / "LIST" SP mailbox-list / 6189 esearch-response / 6190 "STATUS" SP mailbox SP "(" [status-att-list] ")" / 6191 number SP "EXISTS" / Namespace-Response 6193 mailbox-list = "(" [mbx-list-flags] ")" SP 6194 (DQUOTE QUOTED-CHAR DQUOTE / nil) SP mailbox 6195 [SP mbox-list-extended] 6196 ; This is the list information pointed to by the ABNF 6197 ; item "mailbox-data", which is defined in [IMAP4] 6199 mbox-list-extended = "(" [mbox-list-extended-item 6200 *(SP mbox-list-extended-item)] ")" 6202 mbox-list-extended-item = mbox-list-extended-item-tag SP 6203 tagged-ext-val 6205 mbox-list-extended-item-tag = astring 6206 ; The content MUST conform to either "eitem-vendor-tag" 6207 ; or "eitem-standard-tag" ABNF productions. 6209 mbox-or-pat = list-mailbox / patterns 6211 mbx-list-flags = *(mbx-list-oflag SP) mbx-list-sflag 6212 *(SP mbx-list-oflag) / 6213 mbx-list-oflag *(SP mbx-list-oflag) 6215 mbx-list-oflag = "\Noinferiors" / child-mbox-flag / 6216 "\Subscribed" / "\Remote" / flag-extension 6217 ; Other flags; multiple possible per LIST response 6219 mbx-list-sflag = "\NonExistent" / "\Noselect" / "\Marked" / "\Unmarked" 6220 ; Selectability flags; only one per LIST response 6222 media-basic = ((DQUOTE ("APPLICATION" / "AUDIO" / "IMAGE" / 6223 "FONT" / "MESSAGE" / "MODEL" / "VIDEO" ) DQUOTE) 6224 / string) 6225 SP media-subtype 6226 ; Defined in [MIME-IMT]. 6227 ; FONT defined in RFC 8081. 6229 media-message = DQUOTE "MESSAGE" DQUOTE SP 6230 DQUOTE ("RFC822" / "GLOBAL") DQUOTE 6231 ; Defined in [MIME-IMT] 6233 media-subtype = string 6234 ; Defined in [MIME-IMT] 6236 media-text = DQUOTE "TEXT" DQUOTE SP media-subtype 6237 ; Defined in [MIME-IMT] 6239 message-data = nz-number SP ("EXPUNGE" / ("FETCH" SP msg-att)) 6241 move = "MOVE" SP sequence-set SP mailbox 6243 msg-att = "(" (msg-att-dynamic / msg-att-static) 6244 *(SP (msg-att-dynamic / msg-att-static)) ")" 6246 msg-att-dynamic = "FLAGS" SP "(" [flag-fetch *(SP flag-fetch)] ")" 6247 ; MAY change for a message 6249 msg-att-static = "ENVELOPE" SP envelope / "INTERNALDATE" SP date-time / 6250 "RFC822.SIZE" SP number / 6251 "BODY" ["STRUCTURE"] SP body / 6252 "BODY" section ["<" number ">"] SP nstring / 6253 "BINARY" section-binary SP (nstring / literal8) / 6254 "BINARY.SIZE" section-binary SP number / 6255 "UID" SP uniqueid 6256 ; MUST NOT change for a message 6258 name-component = 1*UTF8-CHAR 6259 ; MUST NOT contain ".", "/", "%", or "*" 6261 Namespace = nil / "(" 1*Namespace-Descr ")" 6263 Namespace-Command = "NAMESPACE" 6265 Namespace-Descr = "(" string SP 6266 (DQUOTE QUOTED-CHAR DQUOTE / nil) 6267 [Namespace-Response-Extensions] ")" 6269 Namespace-Response-Extensions = *Namespace-Response-Extension 6271 Namespace-Response-Extension = SP string SP 6272 "(" string *(SP string) ")" 6274 Namespace-Response = "NAMESPACE" SP Namespace 6275 SP Namespace SP Namespace 6276 ; The first Namespace is the Personal Namespace(s). 6277 ; The second Namespace is the Other Users' 6278 ; Namespace(s). 6279 ; The third Namespace is the Shared Namespace(s). 6281 nil = "NIL" 6282 nstring = string / nil 6284 number = 1*DIGIT 6285 ; Unsigned 32-bit integer 6286 ; (0 <= n < 4,294,967,296) 6288 number64 = 1*DIGIT 6289 ; Unsigned 63-bit integer 6290 ; (0 <= n <= 9,223,372,036,854,775,807) 6292 nz-number = digit-nz *DIGIT 6293 ; Non-zero unsigned 32-bit integer 6294 ; (0 < n < 4,294,967,296) 6296 oldname-extended-item = "OLDNAME" SP "(" mailbox ")" 6297 ; Extended data item (mbox-list-extended-item) 6298 ; returned in a LIST response when a mailbox is 6299 ; renamed or deleted. Also returned when 6300 ; the server canonicalized the provided mailbox 6301 ; name. 6302 ; Note 1: the OLDNAME tag can be returned 6303 ; with or without surrounding quotes, as per 6304 ; mbox-list-extended-item-tag production. 6306 option-extension = (option-standard-tag / option-vendor-tag) 6307 [SP option-value] 6309 option-standard-tag = atom 6310 ; an option defined in a Standards Track or 6311 ; Experimental RFC 6313 option-val-comp = astring / 6314 option-val-comp *(SP option-val-comp) / 6315 "(" option-val-comp ")" 6317 option-value = "(" option-val-comp ")" 6319 option-vendor-tag = vendor-token "-" atom 6320 ; a vendor-specific option, non-standard 6322 partial-range = number ["." nz-number] 6323 ; Copied from RFC 5092 (IMAP URL) 6325 partial = "<" number "." nz-number ">" 6326 ; Partial FETCH request. 0-based offset of 6327 ; the first octet, followed by the number of octets 6328 ; in the fragment. 6330 password = astring 6332 patterns = "(" list-mailbox ")" 6333 ; [RFC5258] supports multiple patterns, 6334 ; but this document only requires one 6335 ; to be supported. 6336 ; If the server is also implementing 6337 ; [RFC5258], "patterns" syntax from that 6338 ; document must be followed. 6340 quoted = DQUOTE *QUOTED-CHAR DQUOTE 6342 QUOTED-CHAR = / 6343 "\" quoted-specials / UTF8-2 / UTF8-3 / UTF8-4 6345 quoted-specials = DQUOTE / "\" 6347 rename = "RENAME" SP mailbox SP mailbox 6348 ; Use of INBOX as a destination gives a NO error 6350 response = *(continue-req / response-data) response-done 6352 response-data = "*" SP (resp-cond-state / resp-cond-bye / 6353 mailbox-data / message-data / capability-data / 6354 enable-data) CRLF 6356 response-done = response-tagged / response-fatal 6358 response-fatal = "*" SP resp-cond-bye CRLF 6359 ; Server closes connection immediately 6361 response-tagged = tag SP resp-cond-state CRLF 6363 resp-code-apnd = "APPENDUID" SP nz-number SP append-uid 6365 resp-code-copy = "COPYUID" SP nz-number SP uid-set SP uid-set 6367 resp-cond-auth = ("OK" / "PREAUTH") SP resp-text 6368 ; Authentication condition 6370 resp-cond-bye = "BYE" SP resp-text 6372 resp-cond-state = ("OK" / "NO" / "BAD") SP resp-text 6373 ; Status condition 6375 resp-specials = "]" 6377 resp-text = ["[" resp-text-code "]" SP] [text] 6378 resp-text-code = "ALERT" / 6379 "BADCHARSET" [SP "(" charset *(SP charset) ")" ] / 6380 capability-data / "PARSE" / 6381 "PERMANENTFLAGS" SP 6382 "(" [flag-perm *(SP flag-perm)] ")" / 6383 "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / 6384 "UIDNEXT" SP nz-number / "UIDVALIDITY" SP nz-number / 6385 resp-code-apnd / resp-code-copy / "UIDNOTSTICKY" / 6386 "UNAVAILABLE" / "AUTHENTICATIONFAILED" / 6387 "AUTHORIZATIONFAILED" / "EXPIRED" / 6388 "PRIVACYREQUIRED" / "CONTACTADMIN" / "NOPERM" / 6389 "INUSE" / "EXPUNGEISSUED" / "CORRUPTION" / 6390 "SERVERBUG" / "CLIENTBUG" / "CANNOT" / 6391 "LIMIT" / "OVERQUOTA" / "ALREADYEXISTS" / 6392 "NONEXISTENT" / "NOTSAVED" / "HASCHILDREN" / 6393 "CLOSED" / 6394 "UNKNOWN-CTE" / 6395 atom [SP 1*] 6397 return-option = "SUBSCRIBED" / "CHILDREN" / status-option / 6398 option-extension 6400 search = "SEARCH" [search-return-opts] 6401 SP search-program 6403 search-correlator = SP "(" "TAG" SP tag-string ")" 6405 search-key = "ALL" / "ANSWERED" / "BCC" SP astring / 6406 "BEFORE" SP date / "BODY" SP astring / 6407 "CC" SP astring / "DELETED" / "FLAGGED" / 6408 "FROM" SP astring / "KEYWORD" SP flag-keyword / 6409 "ON" SP date / "SEEN" / 6410 "SINCE" SP date / "SUBJECT" SP astring / 6411 "TEXT" SP astring / "TO" SP astring / 6412 "UNANSWERED" / "UNDELETED" / "UNFLAGGED" / 6413 "UNKEYWORD" SP flag-keyword / "UNSEEN" / 6414 ; Above this line were in [IMAP2] 6415 "DRAFT" / "HEADER" SP header-fld-name SP astring / 6416 "LARGER" SP number / "NOT" SP search-key / 6417 "OR" SP search-key SP search-key / 6418 "SENTBEFORE" SP date / "SENTON" SP date / 6419 "SENTSINCE" SP date / "SMALLER" SP number / 6420 "UID" SP sequence-set / "UNDRAFT" / sequence-set / 6421 "(" search-key *(SP search-key) ")" 6423 search-modifier-name = tagged-ext-label 6425 search-mod-params = tagged-ext-val 6426 ; This non-terminal shows recommended syntax 6427 ; for future extensions. 6429 search-program = ["CHARSET" SP charset SP] 6430 search-key *(SP search-key) 6431 ; CHARSET argument to SEARCH MUST be 6432 ; registered with IANA. 6434 search-ret-data-ext = search-modifier-name SP search-return-value 6435 ; Note that not every SEARCH return option 6436 ; is required to have the corresponding 6437 ; ESEARCH return data. 6439 search-return-data = "MIN" SP nz-number / 6440 "MAX" SP nz-number / 6441 "ALL" SP sequence-set / 6442 "COUNT" SP number / 6443 search-ret-data-ext 6444 ; All return data items conform to 6445 ; search-ret-data-ext syntax. 6446 ; Note that "$" marker is not allowed 6447 ; after the ALL return data item. 6449 search-return-opts = SP "RETURN" SP "(" [search-return-opt 6450 *(SP search-return-opt)] ")" 6452 search-return-opt = "MIN" / "MAX" / "ALL" / "COUNT" / 6453 "SAVE" / 6454 search-ret-opt-ext 6455 ; conforms to generic search-ret-opt-ext 6456 ; syntax 6458 search-ret-opt-ext = search-modifier-name [SP search-mod-params] 6460 search-return-value = tagged-ext-val 6461 ; Data for the returned search option. 6462 ; A single "nz-number"/"number"/"number64" value 6463 ; can be returned as an atom (i.e., without 6464 ; quoting). A sequence-set can be returned 6465 ; as an atom as well. 6467 section = "[" [section-spec] "]" 6469 section-binary = "[" [section-part] "]" 6471 section-msgtext = "HEADER" / "HEADER.FIELDS" [".NOT"] SP header-list / 6472 "TEXT" 6473 ; top-level or MESSAGE/RFC822 or MESSAGE/GLOBAL part 6475 section-part = nz-number *("." nz-number) 6476 ; body part reference. 6477 ; Allows for accessing nested body parts. 6479 section-spec = section-msgtext / (section-part ["." section-text]) 6481 section-text = section-msgtext / "MIME" 6482 ; text other than actual body part (headers, etc.) 6484 select = "SELECT" SP mailbox 6486 seq-number = nz-number / "*" 6487 ; message sequence number (COPY, FETCH, STORE 6488 ; commands) or unique identifier (UID COPY, 6489 ; UID FETCH, UID STORE commands). 6490 ; * represents the largest number in use. In 6491 ; the case of message sequence numbers, it is 6492 ; the number of messages in a non-empty mailbox. 6493 ; In the case of unique identifiers, it is the 6494 ; unique identifier of the last message in the 6495 ; mailbox or, if the mailbox is empty, the 6496 ; mailbox's current UIDNEXT value. 6497 ; The server should respond with a tagged BAD 6498 ; response to a command that uses a message 6499 ; sequence number greater than the number of 6500 ; messages in the selected mailbox. This 6501 ; includes "*" if the selected mailbox is empty. 6503 seq-range = seq-number ":" seq-number 6504 ; two seq-number values and all values between 6505 ; these two regardless of order. 6506 ; Example: 2:4 and 4:2 are equivalent and indicate 6507 ; values 2, 3, and 4. 6508 ; Example: a unique identifier sequence range of 6509 ; 3291:* includes the UID of the last message in 6510 ; the mailbox, even if that value is less than 3291. 6512 sequence-set = (seq-number / seq-range) ["," sequence-set] 6513 ; set of seq-number values, regardless of order. 6514 ; Servers MAY coalesce overlaps and/or execute the 6515 ; sequence in any order. 6516 ; Example: a message sequence number set of 6517 ; 2,4:7,9,12:* for a mailbox with 15 messages is 6518 ; equivalent to 2,4,5,6,7,9,12,13,14,15 6519 ; Example: a message sequence number set of *:4,5:7 6520 ; for a mailbox with 10 messages is equivalent to 6521 ; 10,9,8,7,6,5,4,5,6,7 and MAY be reordered and 6522 ; overlap coalesced to be 4,5,6,7,8,9,10. 6524 sequence-set =/ seq-last-command 6525 ; Allow for "result of the last command" indicator. 6527 seq-last-command = "$" 6529 status = "STATUS" SP mailbox SP 6530 "(" status-att *(SP status-att) ")" 6532 status-att = "MESSAGES" / "UIDNEXT" / "UIDVALIDITY" / 6533 "UNSEEN" / "DELETED" / "SIZE" 6535 status-att-val = ("MESSAGES" SP number) / 6536 ("UIDNEXT" SP nz-number) / 6537 ("UIDVALIDITY" SP nz-number) / 6538 ("UNSEEN" SP number) / 6539 ("DELETED" SP number) / 6540 ("SIZE" SP number64) 6541 ; Extensions to the STATUS responses 6542 ; should extend this production. 6543 ; Extensions should use the generic 6544 ; syntax defined by tagged-ext. 6546 status-att-list = status-att-val *(SP status-att-val) 6548 status-option = "STATUS" SP "(" status-att *(SP status-att) ")" 6549 ; This ABNF production complies with 6550 ; syntax. 6552 store = "STORE" SP sequence-set SP store-att-flags 6554 store-att-flags = (["+" / "-"] "FLAGS" [".SILENT"]) SP 6555 (flag-list / (flag *(SP flag))) 6557 string = quoted / literal 6559 subscribe = "SUBSCRIBE" SP mailbox 6561 tag = 1* 6563 tag-string = astring 6564 ; represented as 6566 tagged-ext-label = tagged-label-fchar *tagged-label-char 6567 ; Is a valid RFC 3501 "atom". 6569 tagged-label-fchar = ALPHA / "-" / "_" / "." 6571 tagged-label-char = tagged-label-fchar / DIGIT / ":" 6572 tagged-ext-comp = astring / 6573 tagged-ext-comp *(SP tagged-ext-comp) / 6574 "(" tagged-ext-comp ")" 6575 ; Extensions that follow this general 6576 ; syntax should use nstring instead of 6577 ; astring when appropriate in the context 6578 ; of the extension. 6579 ; Note that a message set or a "number" 6580 ; can always be represented as an "atom". 6581 ; An URL should be represented as 6582 ; a "quoted" string. 6584 tagged-ext-simple = sequence-set / number / number64 6586 tagged-ext-val = tagged-ext-simple / 6587 "(" [tagged-ext-comp] ")" 6589 text = 1*(TEXT-CHAR / UTF8-2 / UTF8-3 / UTF8-4) 6590 ; Non ASCII text can only be returned 6591 ; after ENABLE IMAP4rev2 command 6593 TEXT-CHAR = 6595 time = 2DIGIT ":" 2DIGIT ":" 2DIGIT 6596 ; Hours minutes seconds 6598 uid = "UID" SP 6599 (copy / move / fetch / search / store / uid-expunge) 6600 ; Unique identifiers used instead of message 6601 ; sequence numbers 6603 uid-expunge = "EXPUNGE" SP sequence-set 6604 ; Unique identifiers used instead of message 6605 ; sequence numbers 6607 uid-set = (uniqueid / uid-range) *("," uid-set) 6609 uid-range = (uniqueid ":" uniqueid) 6610 ; two uniqueid values and all values 6611 ; between these two regards of order. 6612 ; Example: 2:4 and 4:2 are equivalent. 6614 uniqueid = nz-number 6615 ; Strictly ascending 6617 unsubscribe = "UNSUBSCRIBE" SP mailbox 6619 userid = astring 6620 UTF8-2 = 6622 UTF8-3 = 6624 UTF8-4 = 6626 vendor-token = "vendor." name-component 6627 ; Definition copied from RFC 2244. 6628 ; MUST be registered with IANA 6630 x-command = "X" atom 6632 zone = ("+" / "-") 4DIGIT 6633 ; Signed four-digit value of hhmm representing 6634 ; hours and minutes east of Greenwich (that is, 6635 ; the amount that the given time differs from 6636 ; Universal Time). Subtracting the timezone 6637 ; from the given time will give the UT form. 6638 ; The Universal Time zone is "+0000". 6640 10. Author's Note 6642 This document is a revision or rewrite of earlier documents, and 6643 supercedes the protocol specification in those documents: RFC 3501, 6644 RFC 2060, RFC 1730, unpublished IMAP2bis.TXT document, RFC 1176, and 6645 RFC 1064. 6647 11. Security Considerations 6649 IMAP4rev2 protocol transactions, including electronic mail data, are 6650 sent in the clear over the network unless protection from snooping is 6651 negotiated. This can be accomplished either by the use of IMAPS 6652 service, STARTTLS command, negotiated privacy protection in the 6653 AUTHENTICATE command, or some other protection mechanism. 6655 11.1. STARTTLS Security Considerations 6657 IMAP client and server implementations MUST comply with relevant TLS 6658 recommendations from [RFC8314]. Additionally, when using TLS 1.2, 6659 IMAP implementations MUST implement 6660 TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite, and SHOULD 6661 implement the TLS_RSA_WITH_AES_128_CBC_SHA [TLS] cipher suite. This 6662 is important as it assures that any two compliant implementations can 6663 be configured to interoperate. Other TLS cipher suites recommended 6664 in RFC 7525 are RECOMMENDED: TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 6665 TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 and 6666 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384. All other cipher suites are 6667 OPTIONAL. Note that this is a change from section 2.1 of [IMAP-TLS]. 6669 During the [TLS] negotiation, the client MUST check its understanding 6670 of the server hostname against the server's identity as presented in 6671 the server Certificate message, in order to prevent man-in-the-middle 6672 attacks. This procedure is described in [RFC7817]. 6674 Both the client and server MUST check the result of the STARTTLS 6675 command and subsequent [TLS] negotiation to see whether acceptable 6676 authentication and/or privacy was achieved. 6678 11.2. COPYUID and APPENDUID response codes 6680 The COPYUID and APPENDUID response codes return information about the 6681 mailbox, which may be considered sensitive if the mailbox has 6682 permissions set that permit the client to COPY or APPEND to the 6683 mailbox, but not SELECT or EXAMINE it. 6685 Consequently, these response codes SHOULD NOT be issued if the client 6686 does not have access to SELECT or EXAMINE the mailbox. 6688 11.3. LIST command and Other Users' namespace 6690 In response to a LIST command containing an argument of the Other 6691 Users' Namespace prefix, a server SHOULD NOT list users that have not 6692 granted list access to their personal mailboxes to the currently 6693 authenticated user. Providing such a list, could compromise security 6694 by potentially disclosing confidential information of who is located 6695 on the server, or providing a starting point of a list of user 6696 accounts to attack. 6698 11.4. Other Security Considerations 6700 A server error message for an AUTHENTICATE command which fails due to 6701 invalid credentials SHOULD NOT detail why the credentials are 6702 invalid. 6704 Use of the LOGIN command sends passwords in the clear. This can be 6705 avoided by using the AUTHENTICATE command with a [SASL] mechanism 6706 that does not use plaintext passwords, by first negotiating 6707 encryption via STARTTLS or some other protection mechanism. 6709 A server implementation MUST implement a configuration that, at the 6710 time of authentication, requires: 6711 (1) The STARTTLS command has been negotiated. 6712 OR 6713 (2) Some other mechanism that protects the session from password 6714 snooping has been provided. 6715 OR 6716 (3) The following measures are in place: 6718 (a) The LOGINDISABLED capability is advertised, and [SASL] mechanisms 6719 (such as PLAIN) using plaintext passwords are NOT advertised in the 6720 CAPABILITY list. 6721 AND 6722 (b) The LOGIN command returns an error even if the password is 6723 correct. 6724 AND 6725 (c) The AUTHENTICATE command returns an error with all [SASL] 6726 mechanisms that use plaintext passwords, even if the password is 6727 correct. 6729 A server error message for a failing LOGIN command SHOULD NOT specify 6730 that the user name, as opposed to the password, is invalid. 6732 A server SHOULD have mechanisms in place to limit or delay failed 6733 AUTHENTICATE/LOGIN attempts. 6735 Additional security considerations are discussed in the section 6736 discussing the AUTHENTICATE (see Section 6.2.2) and LOGIN (see 6737 Section 6.2.3) commands. 6739 12. IANA Considerations 6741 IANA is requested to update "Service Names and Transport Protocol 6742 Port Numbers" registry as follows: 6744 1. Registration for TCP port 143 and the corresponding "imap" 6745 service name should be updated to point to this document and RFC 6746 3501. 6748 2. Registration for TCP port 993 and the corresponding "imaps" 6749 service name should be updated to point to this document, RFC 6750 8314 and RFC 3501. 6752 3. Both UDP port 143 and UDP port 993 should be marked as "Reserved" 6753 in the registry. 6755 Additional IANA actions are specified in subsection of this section. 6757 12.1. Updates to IMAP4 Capabilities registry 6759 IMAP4 capabilities are registered by publishing a standards track or 6760 IESG approved informational or experimental RFC. The registry is 6761 currently located at: https://www.iana.org/assignments/ 6762 imap4-capabilities 6763 As this specification revises the AUTH= prefix, STARTTLS and 6764 LOGINDISABLED extensions, IANA is requested to update registry 6765 entries for these 3 extensions to point to this document. 6767 12.2. GSSAPI/SASL service name 6769 GSSAPI/Kerberos/SASL service names are registered by publishing a 6770 standards track or IESG approved experimental RFC. The registry is 6771 currently located at: https://www.iana.org/assignments/gssapi- 6772 service-names 6774 IANA is requested to update the "imap" service name previously 6775 registered in RFC 3501, to point to this document. 6777 12.3. LIST Selection Options, LIST Return Options, LIST extended data 6778 items 6780 [RFC5258] specifies IANA registration procedures for LIST Selection 6781 Options, LIST Return Options, LIST extended data items. This 6782 document doesn't change these registration procedures. In particular 6783 LIST selection options Section 6.3.9.1 and LIST return options 6784 Section 6.3.9.2 are registered using the procedure specified in 6785 Section 9 of [RFC5258] (and using the registration template from 6786 Section 9.3 of [RFC5258]). LIST Extended Data Items are registered 6787 using the registration template from Section 9.6 of [RFC5258]). 6789 IANA is requested to add a reference to [RFCXXXX] for the "OLDNAME" 6790 LIST-EXTENDED extended data item entry. This is in addition to the 6791 existing reference to [RFC5465]. 6793 13. References 6795 13.1. Normative References 6797 [RFC5258] Leiba, B. and A. Melnikov, "Internet Message Access 6798 Protocol version 4 - LIST Command Extensions", RFC 5258, 6799 DOI 10.17487/RFC5258, June 2008, 6800 . 6802 [RFC5788] Melnikov, A. and D. Cridland, "IMAP4 Keyword Registry", 6803 RFC 5788, DOI 10.17487/RFC5788, March 2010, 6804 . 6806 [ABNF] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax 6807 Specifications: ABNF", STD 68, RFC 5234, January 2008, 6808 . 6810 [ANONYMOUS] 6811 Zeilenga, K., "Anonymous Simple Authentication and 6812 Security Layer (SASL) Mechanism", RFC 4505, June 2006, 6813 . 6815 [CHARSET] Freed, N. and J. Postel, "IANA Charset Registration 6816 Procedures", BCP 19, RFC 2978, October 2000, 6817 . 6819 [SCRAM-SHA-256] 6820 Hansen, T., "SCRAM-SHA-256 and SCRAM-SHA-256-PLUS Simple 6821 Authentication and Security Layer (SASL) Mechanisms", 6822 RFC 7677, DOI 10.17487/RFC7677, November 2015, 6823 . 6825 [DISPOSITION] 6826 Troost, R., Dorner, S., and K. Moore, Ed., "Communicating 6827 Presentation Information in Internet Messages: The 6828 Content-Disposition Header Field", RFC 2183, August 1997, 6829 . 6831 [PLAIN] Zeilenga, K., Ed., "The PLAIN Simple Authentication and 6832 Security Layer (SASL) Mechanism", RFC 4616, August 2006, 6833 . 6835 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 6836 Requirement Levels", BCP 14, RFC 2119, 6837 DOI 10.17487/RFC2119, March 1997, 6838 . 6840 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 6841 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 6842 May 2017, . 6844 [LANGUAGE-TAGS] 6845 Alvestrand, H., "Content Language Headers", RFC 3282, May 6846 2002, . 6848 [LOCATION] 6849 Palme, J., Hopmann, A., and N. Shelness, "MIME 6850 Encapsulation of Aggregate Documents, such as HTML 6851 (MHTML)", RFC 2557, March 1999, 6852 . 6854 [MD5] Myers, J. and M. Rose, "The Content-MD5 Header Field", 6855 RFC 1864, October 1995, 6856 . 6858 [MIME-HDRS] 6859 Moore, K., "MIME (Multipurpose Internet Mail Extensions) 6860 Part Three: Message Header Extensions for Non-ASCII Text", 6861 RFC 2047, November 1996, 6862 . 6864 [MIME-IMB] 6865 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6866 Extensions (MIME) Part One: Format of Internet Message 6867 Bodies", RFC 2045, November 1996, 6868 . 6870 [MIME-IMT] 6871 Freed, N. and N. Borenstein, "Multipurpose Internet Mail 6872 Extensions (MIME) Part Two: Media Types", RFC 2046, 6873 November 1996, . 6875 [RFC2231] Freed, N. and K. Moore, "MIME Parameter Value and Encoded 6876 Word Extensions: Character Sets, Languages, and 6877 Continuations", RFC 2231, DOI 10.17487/RFC2231, November 6878 1997, . 6880 [RFC-5322] 6881 Resnick, P., Ed., "Internet Message Format", RFC 5322, 6882 October 2008, . 6884 [SASL] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 6885 Authentication and Security Layer (SASL)", RFC 4422, June 6886 2006, . 6888 [TLS] Dierks, T. and E. Rescorla, "The Transport Layer Security 6889 (TLS) Protocol Version 1.2", RFC 5246, August 2008, 6890 . 6892 [UTF-7] Goldsmith, D. and M. Davis, "UTF-7 A Mail-Safe 6893 Transformation Format of Unicode", RFC 2152, May 1997, 6894 . 6896 [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO 6897 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 6898 2003, . 6900 [MULTIAPPEND] 6901 Crispin, M., "Internet Message Access Protocol (IMAP) - 6902 MULTIAPPEND Extension", RFC 3502, March 2003, 6903 . 6905 [NET-UNICODE] 6906 Klensin, J. and M. Padlipsky, "Unicode Format for Network 6907 Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008, 6908 . 6910 [I18N-HDRS] 6911 Yang, A., Steele, S., and N. Freed, "Internationalized 6912 Email Headers", RFC 6532, DOI 10.17487/RFC6532, February 6913 2012, . 6915 [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data 6916 Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, 6917 . 6919 [RFC7817] Melnikov, A., "Updated Transport Layer Security (TLS) 6920 Server Identity Check Procedure for Email-Related 6921 Protocols", RFC 7817, DOI 10.17487/RFC7817, March 2016, 6922 . 6924 [RFC8098] Hansen, T., Ed. and A. Melnikov, Ed., "Message Disposition 6925 Notification", STD 85, RFC 8098, DOI 10.17487/RFC8098, 6926 February 2017, . 6928 [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: 6929 Use of Transport Layer Security (TLS) for Email Submission 6930 and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, 6931 . 6933 [IMAP-IMPLEMENTATION] 6934 Leiba, B., "IMAP4 Implementation Recommendations", 6935 RFC 2683, September 1999, 6936 . 6938 [IMAP-MULTIACCESS] 6939 Gahrns, M., "IMAP4 Multi-Accessed Mailbox Practice", 6940 RFC 2180, July 1997, 6941 . 6943 13.2. Informative References (related protocols) 6945 [RFC3503] Melnikov, A., "Message Disposition Notification (MDN) 6946 profile for Internet Message Access Protocol (IMAP)", 6947 RFC 3503, DOI 10.17487/RFC3503, March 2003, 6948 . 6950 [RFC5256] Crispin, M. and K. Murchison, "Internet Message Access 6951 Protocol - SORT and THREAD Extensions", RFC 5256, 6952 DOI 10.17487/RFC5256, June 2008, 6953 . 6955 [RFC2193] Gahrns, M., "IMAP4 Mailbox Referrals", RFC 2193, 6956 DOI 10.17487/RFC2193, September 1997, 6957 . 6959 [RFC3348] Gahrns, M. and R. Cheng, "The Internet Message Action 6960 Protocol (IMAP4) Child Mailbox Extension", RFC 3348, 6961 DOI 10.17487/RFC3348, July 2002, 6962 . 6964 [RFC5465] Gulbrandsen, A., King, C., and A. Melnikov, "The IMAP 6965 NOTIFY Extension", RFC 5465, DOI 10.17487/RFC5465, 6966 February 2009, . 6968 [RFC7888] Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals", 6969 RFC 7888, DOI 10.17487/RFC7888, May 2016, 6970 . 6972 [IMAP-DISC] 6973 Melnikov, A., Ed., "Synchronization Operations for 6974 Disconnected IMAP4 Clients", RFC 4549, June 2006, 6975 . 6977 [IMAP-I18N] 6978 Newman, C., Gulbrandsen, A., and A. Melnikov, "Internet 6979 Message Access Protocol Internationalization", RFC 5255, 6980 DOI 10.17487/RFC5255, June 2008, 6981 . 6983 [IMAP-MODEL] 6984 Crispin, M., "Distributed Electronic Mail Models in 6985 IMAP4", RFC 1733, December 1994, 6986 . 6988 [IMAP-UTF-8] 6989 Resnick, P., Ed., Newman, C., Ed., and S. Shen, Ed., "IMAP 6990 Support for UTF-8", RFC 6855, DOI 10.17487/RFC6855, March 6991 2013, . 6993 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 6994 October 2008, . 6996 [RFC3516] Nerenberg, L., "IMAP4 Binary Content Extension", RFC 3516, 6997 DOI 10.17487/RFC3516, April 2003, 6998 . 7000 [RFC4314] Melnikov, A., "IMAP4 Access Control List (ACL) Extension", 7001 RFC 4314, December 2005, 7002 . 7004 [RFC2087] Myers, J., "IMAP4 QUOTA extension", RFC 2087, January 7005 1997, . 7007 [IMAP-URL] 7008 Melnikov, A., Ed. and C. Newman, "IMAP URL Scheme", 7009 RFC 5092, DOI 10.17487/RFC5092, November 2007, 7010 . 7012 [IMAP-KEYWORDS-REG] 7013 IANA, "IMAP and JMAP Keywords", December 2009, 7014 . 7017 [IMAP-MAILBOX-NAME-ATTRS-REG] 7018 IANA, "IMAP Mailbox Name Attributes", June 2018, 7019 . 7022 [CHARSET-REG] 7023 IANA, "Character Set Registrations", May 2015, 7024 . 7027 13.3. Informative References (historical aspects of IMAP and related 7028 protocols) 7030 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 7031 4rev1", RFC 3501, DOI 10.17487/RFC3501, March 2003, 7032 . 7034 [IMAP-COMPAT] 7035 Crispin, M., "IMAP4 Compatibility with IMAP2bis", 7036 RFC 2061, December 1996, 7037 . 7039 [IMAP-HISTORICAL] 7040 Crispin, M., "IMAP4 Compatibility with IMAP2 and 7041 IMAP2bis", RFC 1732, December 1994, 7042 . 7044 [IMAP-OBSOLETE] 7045 Crispin, M., "Internet Message Access Protocol - Obsolete 7046 Syntax", RFC 2062, December 1996, 7047 . 7049 [IMAP2] Crispin, M., "Interactive Mail Access Protocol: Version 7050 2", RFC 1176, August 1990, 7051 . 7053 [RFC-822] Crocker, D., "STANDARD FOR THE FORMAT OF ARPA INTERNET 7054 TEXT MESSAGES", STD 11, RFC 822, August 1982, 7055 . 7057 [IMAP-TLS] 7058 Newman, C., "Using TLS with IMAP, POP3 and ACAP", 7059 RFC 2595, June 1999, 7060 . 7062 Appendix A. Backward compatibility with IMAP4rev1 7064 An implementation that wants to remain compatible with IMAP4rev1 can 7065 advertise both IMAP4rev1 and IMAP4rev2 in its CAPABILITY response/ 7066 response code. While some IMAP4rev1 responses were removed in 7067 IMAP4rev2, their presence will not break IMAP4rev2-only clients. 7069 If both IMAP4rev1 and IMAP4rev2 are advertised, an IMAP client that 7070 wants to use IMAP4rev2 MUST issue an "ENABLE IMAP4rev2" command. 7072 Servers advertising both IMAP4rev1 and IMAP4rev2 MUST NOT generate 7073 UTF-8 quoted strings unless the client has issued "ENABLE IMAP4rev2". 7074 Consider implementation of mechanisms described or referenced in 7075 [IMAP-UTF-8] to achieve this goal. 7077 Servers advertising both IMAP4rev1 and IMAP4rev2, and clients 7078 intending to be compatible with IMAP4rev1 servers MUST be compatible 7079 with the international mailbox naming convention described in the 7080 following subsection. 7082 A.1. Mailbox International Naming Convention for compatibility with 7083 IMAP4rev1 7085 Support for the Mailbox International Naming Convention described in 7086 this section is not required for IMAP4rev2-only clients and servers. 7088 By convention, international mailbox names in IMAP4rev1 are specified 7089 using a modified version of the UTF-7 encoding described in [UTF-7]. 7090 Modified UTF-7 may also be usable in servers that implement an 7091 earlier version of this protocol. 7093 In modified UTF-7, printable US-ASCII characters, except for "&", 7094 represent themselves; that is, characters with octet values 0x20-0x25 7095 and 0x27-0x7e. The character "&" (0x26) is represented by the two- 7096 octet sequence "&-". 7098 All other characters (octet values 0x00-0x1f and 0x7f-0xff) are 7099 represented in modified BASE64, with a further modification from 7100 [UTF-7] that "," is used instead of "/". Modified BASE64 MUST NOT be 7101 used to represent any printing US-ASCII character which can represent 7102 itself. Only characters inside the modified BASE64 alphabet are 7103 permitted in modified BASE64 text. 7105 "&" is used to shift to modified BASE64 and "-" to shift back to US- 7106 ASCII. There is no implicit shift from BASE64 to US-ASCII, and null 7107 shifts ("-&" while in BASE64; note that "&-" while in US-ASCII means 7108 "&") are not permitted. However, all names start in US-ASCII, and 7109 MUST end in US-ASCII; that is, a name that ends with a non-ASCII 7110 ISO-10646 character MUST end with a "-"). 7112 The purpose of these modifications is to correct the following 7113 problems with UTF-7: 7115 1. UTF-7 uses the "+" character for shifting; this conflicts with 7116 the common use of "+" in mailbox names, in particular USENET 7117 newsgroup names. 7119 2. UTF-7's encoding is BASE64 which uses the "/" character; this 7120 conflicts with the use of "/" as a popular hierarchy delimiter. 7122 3. UTF-7 prohibits the unencoded usage of "\"; this conflicts with 7123 the use of "\" as a popular hierarchy delimiter. 7125 4. UTF-7 prohibits the unencoded usage of "~"; this conflicts with 7126 the use of "~" in some servers as a home directory indicator. 7128 5. UTF-7 permits multiple alternate forms to represent the same 7129 string; in particular, printable US-ASCII characters can be 7130 represented in encoded form. 7132 Although modified UTF-7 is a convention, it establishes certain 7133 requirements on server handling of any mailbox name with an embedded 7134 "&" character. In particular, server implementations MUST preserve 7135 the exact form of the modified BASE64 portion of a modified UTF-7 7136 name and treat that text as case-sensitive, even if names are 7137 otherwise case-insensitive or case-folded. 7139 Server implementations SHOULD verify that any mailbox name with an 7140 embedded "&" character, used as an argument to CREATE, is: in the 7141 correctly modified UTF-7 syntax, has no superfluous shifts, and has 7142 no encoding in modified BASE64 of any printing US-ASCII character 7143 which can represent itself. However, client implementations MUST NOT 7144 depend upon the server doing this, and SHOULD NOT attempt to create a 7145 mailbox name with an embedded "&" character unless it complies with 7146 the modified UTF-7 syntax. 7148 Server implementations which export a mail store that does not follow 7149 the modified UTF-7 convention MUST convert to modified UTF-7 any 7150 mailbox name that contains either non-ASCII characters or the "&" 7151 character. 7153 For example, here is a mailbox name which mixes English, Chinese, 7154 and Japanese text: ~peter/mail/&U,BTFw-/&ZeVnLIqe- 7156 For example, the string "&Jjo!" is not a valid mailbox name 7157 because it does not contain a shift to US-ASCII before the "!". 7158 The correct form is "&Jjo-!". The string "&U,BTFw-&ZeVnLIqe-" is 7159 not permitted because it contains a superfluous shift. The 7160 correct form is "&U,BTF2XlZyyKng-". 7162 Appendix B. Backward compatibility with BINARY extension 7164 IMAP4rev2 is incorporates subset of functionality provided by the 7165 BINARY extension [RFC3516], in particular it includes additional 7166 FETCH items (BINARY, BINARY.PEEK and BINARY.SIZE), but not extensions 7167 to the APPEND command. IMAP4rev2 implementations that supports full 7168 RFC 3516 functionality need to also advertise the BINARY token in the 7169 CAPABILITY response. 7171 Appendix C. Backward compatibility with LIST-EXTENDED extension 7173 IMAP4rev2 is incorporates most of functionality provided by the LIST- 7174 EXTENDED extension [RFC5258]. In particular, multiple mailbox 7175 patterns syntax is not supported in IMAP4rev2, unless LIST-EXTENDED 7176 capability is also advertised in CAPABILITY response/response code. 7178 Appendix D. Changes from RFC 3501 / IMAP4rev1 7180 The following is the plan for remaining changes. The plan might 7181 change over time. 7183 1. Revise IANA registration of IMAP extensions and give advice on 7184 use of "X-" convention. 7186 2. Add a section on other recommended extensions? 7188 The following changes were already done: 7190 1. Fold in the following extensions/RFC: RFC 5530 (IMAP Response 7191 Codes), UIDPLUS, ENABLE, ESEARCH, SPECIAL-USE (list of new 7192 mailbox attributes), LITERAL-, NAMESPACE, SASL-IR, LIST-STATUS, 7193 SEARCHRES, IDLE, MOVE. 7195 2. Add CLOSED response code (from CONDSTORE). 7197 3. Add support for $Phishing, $Junk, $NonJunk, $MDNSent and 7198 $Forwarded IMAP keywords. Add more examples showing their use? 7200 4. Require all unsolicited FETCH updates to include UID. 7202 5. Update recommendations on TLS ciphers to match UTA WG work (as 7203 per RFC 8314, RFC 7525 and RFC 7817). 7205 6. Fold in the following extensions/RFC: Base LIST-EXTENDED syntax 7206 plus deprecate LSUB (replace it with LIST \Subscribed) minus the 7207 requirement to support multiple list patterns, BINARY (only the 7208 FETCH changes on leaf body part and make APPEND related ones 7209 optional. See the mailing list discussion). 7211 7. Add STATUS SIZE (total mailbox size). Add STATUS DELETED (number 7212 of messages with \Deleted flag set). 7214 8. Drop UTF-7, all mailboxes are always in UTF-8. 7216 The following changes since RFC 3501 were done so far: 7218 1. Folded in IMAP UNSELECT (RFC 3691), UIDPLUS (RFC 4315), ESEARCH 7219 (RFC 4731), SEARCHRES (RFC 5182), ENABLE (RFC 5161), IDLE (RFC 7220 2177), SASL-IR (RFC 4959), LIST-STATUS (RFC 5819) and MOVE (RFC 7221 6851) extensions. Also folded RFC 5530 and FETCH side of the 7222 BINARY extension (RFC 3516). 7224 2. Clarified that server should decode parameter value 7225 continuations as described in [RFC2231]. This requirement was 7226 hidden in RFC 2231 itself. 7228 3. SEARCH command now requires to return ESEARCH response (SEARCH 7229 response is now deprecated). 7231 4. Clarified which SEARCH keys has to use substring match and which 7232 don't. 7234 5. Added CLOSED response code from RFC 7162. SELECT/EXAMINE when a 7235 mailbox is already selected now require for the CLOSED response 7236 code to be returned. 7238 6. SELECT/EXAMINE are now required to return untagged LIST 7239 response. 7241 7. Updated to use modern TLS-related recommendations as per RFC 7242 8314, RFC 7817, RFC 7525. 7244 8. For future extensibility extended ABNF for tagged-ext-simple to 7245 allow for bare number64. 7247 9. Added SHOULD level requirement on IMAP servers to support 7248 $MDNSent, $Forwarded, $Junk, $NonJunk and $Phishing keywords. 7250 10. Added STATUS SIZE (RFC 8438) and STATUS DELETED. 7252 11. Mailbox names and message headers now allow for UTF-8. Support 7253 for Modified UTF-7 in mailbox names is not required, unless 7254 compatibility with IMAP4rev1 is desired. 7256 12. UNSEEN response code on SELECT/EXAMINE is now deprecated. 7258 13. RECENT response on SELECT/EXAMINE, \Recent flag, RECENT STATUS, 7259 SEARCH NEW items are now deprecated. 7261 14. Clarified that the server doesn't need to send a new 7262 PERMANENTFLAGS response code when a new keyword was successfully 7263 added and the server advertised \* earlier for the same mailbox. 7265 15. Removed the CHECK command. Clients should use NOOP instead. 7267 16. RFC822, RFC822.HEADER and RFC822.TEXT FETCH data items were 7268 deprecated. Clients should use the corresponding BODY[] 7269 variants instead. 7271 17. Replaced DIGEST-MD5 SASL mechanism with SCRAM-SHA-256. DIGEST- 7272 MD5 was deprecated. 7274 18. LSUB command was deprecated. Clients should use LIST 7275 (SUBSCRIBED) instead. 7277 19. resp-text ABNF non terminal was updated to allow for empty text. 7279 20. IDLE command can now return updates not related to the currently 7280 selected mailbox state. 7282 21. All unsolicited FETCH updates are required to include UID. 7284 22. Clarified that client implementations MUST ignore response codes 7285 that they do not recognize. (Change from a SHOULD to a MUST.) 7287 23. After ENABLE IMAP4rev2 human readable response text can include 7288 non ASCII encoded in UTF-8. 7290 Appendix E. Acknowledgement 7292 Earlier versions of this document were edited by Mark Crispin. 7293 Sadly, he is no longer available to help with this work. Editors of 7294 this revisions are hoping that Mark would have approved. 7296 Chris Newman has contributed text on I18N and use of UTF-8 in 7297 messages and mailbox names. 7299 Thank you to Tony Hansen for helping with the index generation. 7300 Thank you to Timo Sirainen, Bron Gondwana, Stephan Bosch and Arnt 7301 Gulbrandsen for extensive feedback. 7303 This document incorporate text from RFC 4315 (by Mark Crispin), RFC 7304 4466 (by Cyrus Daboo), RFC 4731 (by Dave Cridland), RFC 5161 (by Arnt 7305 Gulbrandsen), RFC 5465 (by Arnt Gulbrandsen and Curtis King), RFC 7306 5530 (by Arnt Gulbrandsen), RFC 5819 (by Timo Sirainen), RFC 6154 (by 7307 Jamie Nicolson), RFC 8438 (by Stephan Bosch) so work done by authors/ 7308 editors of these documents is appreciated. Note that editors of this 7309 document were redacted from the above list. 7311 The CHILDREN return option was originally proposed by Mike Gahrns and 7312 Raymond Cheng in [RFC3348]. Most of the information in 7313 Section 6.3.9.5 is taken directly from their original specification 7314 [RFC3348]. 7316 Index 7318 $ 7319 $Forwarded (predefined flag) 12 7320 $Junk (predefined flag) 12 7321 $MDNSent (predefined flag) 12 7322 $NotJunk (predefined flag) 12 7323 $Phishing (predefined flag) 12 7325 + 7326 +FLAGS 92 7327 +FLAGS.SILENT 92 7329 - 7330 -FLAGS 92 7331 -FLAGS.SILENT 92 7333 A 7334 ALERT (response code) 99 7335 ALL (fetch item) 88 7336 ALL (search key) 78 7337 ALL (search result option) 76 7338 ALREADYEXISTS (response code) 99 7339 ANSWERED (search key) 78 7340 APPEND (command) 68 7341 APPENDUID (response code) 100 7342 AUTHENTICATE (command) 29 7343 AUTHENTICATIONFAILED (response code) 100 7344 AUTHORIZATIONFAILED (response code) 101 7346 B 7347 BAD (response) 108 7348 BADCHARSET (response code) 101 7349 BCC (search key) 78 7350 BEFORE (search key) 78 7351 BINARY.PEEK[]<> (fetch item) 88 7352 BINARY.SIZE[] (fetch item) 89 7353 BINARY.SIZE[] (fetch result) 118 7354 BINARY[]<> (fetch result) 118 7355 BINARY[]<> (fetch item) 88 7356 BODY (fetch item) 89 7357 BODY (fetch result) 119 7358 BODY (search key) 78 7359 BODY.PEEK[
]<> (fetch item) 89 7360 BODYSTRUCTURE (fetch item) 90 7361 BODYSTRUCTURE (fetch result) 119 7362 BODY[
]<> (fetch result) 119 7363 BODY[
]<> (fetch item) 89 7364 BYE (response) 109 7365 Body Structure (message attribute) 14 7367 C 7368 CANNOT (response code) 101 7369 CAPABILITY (command) 25 7370 CAPABILITY (response code) 101 7371 CAPABILITY (response) 110 7372 CC (search key) 78 7373 CLIENTBUG (response code) 101 7374 CLOSE (command) 74 7375 CLOSED (response code) 102 7376 CONTACTADMIN (response code) 102 7377 COPY (command) 93 7378 COPYUID (response code) 102 7379 CORRUPTION (response code) 103 7380 COUNT (search result option) 76 7381 CREATE (command) 38 7383 D 7384 DELETE (command) 39 7385 DELETED (search key) 78 7386 DELETED (status item) 68 7387 DRAFT (search key) 78 7389 E 7390 ENABLE (command) 33 7391 ENVELOPE (fetch item) 90 7392 ENVELOPE (fetch result) 122 7393 ESEARCH (response) 115 7394 EXAMINE (command) 37 7395 EXPIRED (response code) 103 7396 EXPUNGE (command) 75 7397 EXPUNGE (response) 117 7398 EXPUNGEISSUED (response code) 103 7399 Envelope Structure (message attribute) 14 7401 F 7402 FAST (fetch item) 88 7403 FETCH (command) 87 7404 FETCH (response) 118 7405 FLAGGED (search key) 78 7406 FLAGS (fetch item) 90 7407 FLAGS (fetch result) 123 7408 FLAGS (response) 116 7409 FLAGS (store command data item) 92 7410 FLAGS.SILENT (store command data item) 92 7411 FROM (search key) 79 7412 FULL (fetch item) 88 7413 Flags (message attribute) 11 7415 H 7416 HASCHILDREN (response code) 103 7417 HEADER (part specifier) 90 7418 HEADER (search key) 79 7419 HEADER.FIELDS (part specifier) 90 7420 HEADER.FIELDS.NOT (part specifier) 90 7422 I 7423 IDLE (command) 71 7424 INTERNALDATE (fetch item) 90 7425 INTERNALDATE (fetch result) 123 7426 INUSE (response code) 104 7427 Internal Date (message attribute) 13 7429 K 7430 KEYWORD (search key) 79 7431 Keyword (type of flag) 12 7433 L 7434 LARGER (search key) 79 7435 LIMIT (response code) 104 7436 LIST (command) 44 7437 LIST (response) 111 7438 LOGOUT (command) 27 7440 M 7441 MAX (search result option) 76 7442 MAY (specification requirement term) 5 7443 MESSAGES (status item) 68 7444 MIME (part specifier) 91 7445 MIN (search result option) 76 7446 MOVE (command) 94 7447 MUST (specification requirement term) 5 7448 MUST NOT (specification requirement term) 5 7449 Message Sequence Number (message attribute) 11 7451 N 7452 NAMESPACE (command) 62 7453 NAMESPACE (response) 115 7454 NO (response) 108 7455 NONEXISTENT (response code) 104 7456 NOOP (command) 26 7457 NOPERM (response code) 104 7458 NOT (search key) 79 7459 NOT RECOMMENDED (specification requirement term) 5 7461 O 7462 OK (response) 107 7463 ON (search key) 79 7464 OPTIONAL (specification requirement term) 5 7465 OR (search key) 79 7466 OVERQUOTA (response code) 104 7468 P 7469 PARSE (response code) 105 7470 PERMANENTFLAGS (response code) 105 7471 PREAUTH (response) 108 7472 PRIVACYREQUIRED (response code) 105 7473 Permanent Flag (class of flag) 13 7474 Predefined keywords 12 7476 R 7477 READ-ONLY (response code) 106 7478 READ-WRITE (response code) 106 7479 RECOMMENDED (specification requirement term) 5 7480 RENAME (command) 41 7481 REQUIRED (specification requirement term) 5 7482 RFC822.SIZE (fetch item) 90 7483 RFC822.SIZE (fetch result) 123 7485 S 7486 SAVE (search result option) 76 7487 SEARCH (command) 75 7488 SEEN (search key) 79 7489 SELECT (command) 35 7490 SENTBEFORE (search key) 79 7491 SENTON (search key) 79 7492 SENTSINCE (search key) 79 7493 SERVERBUG (response code) 106 7494 SHOULD (specification requirement term) 5 7495 SHOULD NOT (specification requirement term) 5 7496 SINCE (search key) 79 7497 SIZE (status item) 68 7498 SMALLER (search key) 79 7499 STARTTLS (command) 28 7500 STATUS (command) 67 7501 STATUS (response) 115 7502 STORE (command) 92 7503 SUBJECT (search key) 80 7504 SUBSCRIBE (command) 43 7505 Session Flag (class of flag) 13 7506 System Flag (type of flag) 11 7508 T 7509 TEXT (part specifier) 90 7510 TEXT (search key) 80 7511 TO (search key) 80 7512 TRYCREATE (response code) 106 7514 U 7515 UID (command) 96 7516 UID (fetch item) 90 7517 UID (fetch result) 123 7518 UID (search key) 80 7519 UIDNEXT (response code) 106 7520 UIDNEXT (status item) 68 7521 UIDNOTSTICKY (response code) 106 7522 UIDVALIDITY (response code) 107 7523 UIDVALIDITY (status item) 68 7524 UNANSWERED (search key) 80 7525 UNAVAILABLE (response code) 107 7526 UNDELETED (search key) 80 7527 UNDRAFT (search key) 80 7528 UNFLAGGED (search key) 80 7529 UNKEYWORD (search key) 80 7530 UNKNOWN-CTE (response code) 107 7531 UNSEEN (search key) 80 7532 UNSEEN (status item) 68 7533 UNSELECT (command) 74 7534 UNSUBSCRIBE (command) 44 7535 Unique Identifier (UID) (message attribute) 9 7537 X 7538 X (command) 97 7540 [ 7541 [RFC-5322] Size (message attribute) 14 7543 \ 7544 \All (mailbox name attribute) 113 7545 \Answered (system flag) 11 7546 \Archive (mailbox name attribute) 113 7547 \Deleted (system flag) 12 7548 \Draft (system flag) 12 7549 \Drafts (mailbox name attribute) 113 7550 \Flagged (mailbox name attribute) 113 7551 \Flagged (system flag) 11 7552 \HasChildren (mailbox name attribute) 112 7553 \HasNoChildren (mailbox name attribute) 112 7554 \Junk (mailbox name attribute) 113 7555 \Marked (mailbox name attribute) 112 7556 \Noinferiors (mailbox name attribute) 111 7557 \NonExistent (mailbox name attribute) 111 7558 \Noselect (mailbox name attribute) 111 7559 \Recent (system flag) 12 7560 \Remote (mailbox name attribute) 112 7561 \Seen (system flag) 11 7562 \Sent (mailbox name attribute) 113 7563 \Subscribed (mailbox name attribute) 112 7564 \Trash (mailbox name attribute) 113 7565 \Unmarked (mailbox name attribute) 112 7567 Authors' Addresses 7568 Alexey Melnikov (editor) 7569 Isode Ltd 7570 14 Castle Mews 7571 Hampton, Middlesex TW12 2NP 7572 UK 7574 Email: Alexey.Melnikov@isode.com 7576 Barry Leiba (editor) 7577 Futurewei Technologies 7579 Phone: +1 646 827 0648 7580 Email: barryleiba@computer.org 7581 URI: http://internetmessagingtechnology.org/