--- /dev/null
+
+
+
+
+
+
+Network Working Group M. Crispin
+Request for Comments: 3502 University of Washington
+Category: Standards Track March 2003
+
+
+ Internet Message Access Protocol (IMAP) - MULTIAPPEND Extension
+
+Status of this Memo
+
+ This document specifies an Internet standards track protocol for the
+ Internet community, and requests discussion and suggestions for
+ improvements. Please refer to the current edition of the "Internet
+ Official Protocol Standards" (STD 1) for the standardization state
+ and status of this protocol. Distribution of this memo is unlimited.
+
+Copyright Notice
+
+ Copyright (C) The Internet Society (2003). All Rights Reserved.
+
+Abstract
+
+ This document describes the multiappending extension to the Internet
+ Message Access Protocol (IMAP) (RFC 3501). This extension provides
+ substantial performance improvements for IMAP clients which upload
+ multiple messages at a time to a mailbox on the server.
+
+ A server which supports this extension indicates this with a
+ capability name of "MULTIAPPEND".
+
+Terminology
+
+ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+ "SHOULD", "SHOULD NOT", "MAY", and "OPTIONAL" in this document are to
+ be interpreted as described in [KEYWORDS].
+
+Introduction
+
+ The MULTIAPPEND extension permits uploading of multiple messages with
+ a single command. When used in conjunction with the [LITERAL+]
+ extension, the entire upload is accomplished in a single
+ command/response round trip.
+
+ A MULTIAPPEND APPEND operation is atomic; either all messages are
+ successfully appended, or no messages are appended.
+
+ In the base IMAP specification, each message must be appended in a
+ separate command, and there is no mechanism to "unappend" messages if
+ an error occurs while appending. Also, some mail stores may require
+
+
+
+Crispin Standards Track [Page 1]
+\f
+RFC 3502 IMAP MULTIAPPEND March 2003
+
+
+ an expensive "open/lock + sync/unlock/close" operation as part of
+ appending; this can be quite expensive if it must be done on a
+ per-message basis.
+
+ If the server supports both LITERAL+ and pipelining but not
+ MULTIAPPEND, it may be possible to get some of the performance
+ advantages of MULTIAPPEND by doing a pipelined "batch" append.
+ However, it will not work as well as MULTIAPPEND for the following
+ reasons:
+
+ 1) Multiple APPEND commands, even as part of a pipelined batch,
+ are non-atomic by definition. There is no way to revert the
+ mailbox to the state before the batch append in the event of an
+ error.
+
+ 2) It may not be feasible for the server to coalesce pipelined
+ APPEND operations so as to avoid the "open/lock +
+ sync/unlock/close" overhead described above. In any case, such
+ coalescing would be timing dependent and thus potentially
+ unreliable. In particular, with traditional UNIX mailbox files,
+ it is assumed that a lock is held only for a single atomic
+ operation, and many applications disregard any lock that is
+ older than 5 minutes.
+
+ 3) If an error occurs, depending upon the nature of the error,
+ it is possible for additional messages to be appended after the
+ error. For example, the user wants to append 5 messages, but a
+ disk quota error occurs with the third message because of its
+ size. However, the fourth and fifth messages have already been
+ sent in the pipeline, so the mailbox ends up with the first,
+ second, fourth, and fifth messages of the batch appended.
+
+6.3.11. APPEND Command
+
+ Arguments: mailbox name
+ one or more messages to upload, specified as:
+ OPTIONAL flag parenthesized list
+ OPTIONAL date/time string
+ message literal
+
+ Data: no specific responses for this command
+
+ Result: OK - append completed
+ NO - append error: can't append to that mailbox, error
+ in flags or date/time or message text,
+ append cancelled
+ BAD - command unknown or arguments invalid
+
+
+
+
+Crispin Standards Track [Page 2]
+\f
+RFC 3502 IMAP MULTIAPPEND March 2003
+
+
+ The APPEND command appends the literal arguments as new messages
+ to the end of the specified destination mailbox. This argument
+ SHOULD be in the format of an [RFC-2822] message. 8-bit
+ characters are permitted in the message. A server implementation
+ that is unable to preserve 8-bit data properly MUST be able to
+ reversibly convert 8-bit APPEND data to 7-bit using a [MIME-IMB]
+ content transfer encoding.
+
+ Note: There MAY be exceptions, e.g., draft messages, in
+ which required [RFC-2822] header lines are omitted in the
+ message literal argument to APPEND. The full implications
+ of doing so MUST be understood and carefully weighed.
+
+ If a flag parenthesized list is specified, the flags SHOULD be set
+ in the resulting message; otherwise, the flag list of the
+ resulting message is set empty by default.
+
+ If a date-time is specified, the internal date SHOULD be set in
+ the resulting message; otherwise, the internal date of the
+ resulting message is set to the current date and time by default.
+
+ A zero-length message literal argument is an error, and MUST
+ return a NO. This can be used to cancel the append.
+
+ If the append is unsuccessful for any reason (including being
+ cancelled), the mailbox MUST be restored to its state before the
+ APPEND attempt; no partial appending is permitted. The server MAY
+ return an error before processing all the message arguments.
+
+ If the destination mailbox does not exist, a server MUST return an
+ error, and MUST NOT automatically create the mailbox. Unless it
+ is certain that the destination mailbox can not be created, the
+ server MUST send the response code "[TRYCREATE]" as the prefix of
+ the text of the tagged NO response. This gives a hint to the
+ client that it can attempt a CREATE command and retry the APPEND
+ if the CREATE is successful.
+
+ If the mailbox is currently selected, the normal new message
+ actions SHOULD occur. Specifically, the server SHOULD notify the
+ client immediately via an untagged EXISTS response. If the server
+ does not do so, the client MAY issue a NOOP command (or failing
+ that, a CHECK command) after one or more APPEND commands.
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 3]
+\f
+RFC 3502 IMAP MULTIAPPEND March 2003
+
+
+ Example: C: A003 APPEND saved-messages (\Seen) {329}
+ S: + Ready for literal data
+ C: Date: Mon, 7 Feb 1994 21:52:25 -0800 (PST)
+ C: From: Fred Foobar <foobar@Blurdybloop.example.COM>
+ C: Subject: afternoon meeting
+ C: To: mooch@owatagu.example.net
+ C: Message-Id: <B27397-0100000@Blurdybloop.example.COM>
+ C: MIME-Version: 1.0
+ C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
+ C:
+ C: Hello Joe, do you think we can meet at 3:30 tomorrow?
+ C: (\Seen) " 7-Feb-1994 22:43:04 -0800" {295}
+ S: + Ready for literal data
+ C: Date: Mon, 7 Feb 1994 22:43:04 -0800 (PST)
+ C: From: Joe Mooch <mooch@OWaTaGu.example.net>
+ C: Subject: Re: afternoon meeting
+ C: To: foobar@blurdybloop.example.com
+ C: Message-Id: <a0434793874930@OWaTaGu.example.net>
+ C: MIME-Version: 1.0
+ C: Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
+ C:
+ C: 3:30 is fine with me.
+ C:
+ S: A003 OK APPEND completed
+ C: A004 APPEND bogusname (\Flagged) {1023}
+ S: A004 NO [TRYCREATE] No such mailbox as bogusname
+ C: A005 APPEND test (\Flagged) {99}
+ S: + Ready for literal data
+ C: Date: Mon, 7 Feb 2000 22:43:04 -0800 (PST)
+ C: From: Fred Foobar <fred@example.com>
+ C: Subject: hmm...
+ C: {35403}
+ S: A005 NO APPEND failed: Disk quota exceeded
+
+ Note: The APPEND command is not used for message delivery,
+ because it does not provide a mechanism to transfer [SMTP]
+ envelope information.
+
+Modification to IMAP4rev1 Base Protocol Formal Syntax
+
+ The following syntax specification uses the Augmented Backus-Naur
+ Form (ABNF) notation as specified in [ABNF].
+
+ append = "APPEND" SP mailbox 1*append-message
+
+ append-message = [SP flag-list] [SP date-time] SP literal
+
+
+
+
+
+Crispin Standards Track [Page 4]
+\f
+RFC 3502 IMAP MULTIAPPEND March 2003
+
+
+MULTIAPPEND Interaction with UIDPLUS Extension
+
+ Servers which support both MULTIAPPEND and [UIDPLUS] will have the
+ "resp-code-apnd" rule modified as follows:
+
+ resp-code-apnd = "APPENDUID" SP nz-number SP set
+
+ That is, the APPENDUID response code returns as many UIDs as there
+ were messages appended in the multiple append. The UIDs returned
+ should be in the order the articles where appended. The message set
+ may not contain extraneous UIDs or the symbol "*".
+
+Security Considerations
+
+ The MULTIAPPEND extension does not raise any security considerations
+ that are not present in the base [IMAP] protocol, and these issues
+ are discussed in [IMAP]. Nevertheless, it is important to remember
+ that IMAP4rev1 protocol transactions, including electronic mail data,
+ are sent in the clear over the network unless protection from
+ snooping is negotiated, either by the use of STARTTLS, privacy
+ protection is negotiated in the AUTHENTICATE command, or some other
+ protection mechanism is in effect.
+
+Normative References
+
+ [ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
+ Specifications: ABNF", RFC 2234, November 1997.
+
+ [IMAP] Crispin, M., "Internet Message Access Protocol - Version
+ 4rev1", RFC 3501, March 2003.
+
+ [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
+ Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+ [MIME-IMB] Freed, N. and N. Borenstein, "MIME (Multipurpose Internet
+ Mail Extensions) Part One: Format of Internet Message
+ Bodies", RFC 2045, November 1996.
+
+ [RFC-2822] Resnick, P., "Internet Message Format", RFC 2822, April
+ 2001.
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 5]
+\f
+RFC 3502 IMAP MULTIAPPEND March 2003
+
+
+Informative References
+
+ [LITERAL+] Myers, J., "IMAP4 non-synchronizing literals", RFC 2088,
+ January 1997.
+
+ [UIDPLUS] Myers, J., "IMAP4 UIDPLUS extension", RFC 2359, June 1988.
+
+ [SMTP] Klensin, J., Editor, "Simple Mail Transfer Protocol", RFC
+ 2821, April 2001.
+
+Author's Address
+
+ Mark R. Crispin
+ Networks and Distributed Computing
+ University of Washington
+ 4545 15th Avenue NE
+ Seattle, WA 98105-4527
+
+ Phone: (206) 543-5762
+ EMail: MRC@CAC.Washington.EDU
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 6]
+\f
+RFC 3502 IMAP MULTIAPPEND March 2003
+
+
+Full Copyright Statement
+
+ Copyright (C) The Internet Society (2003). All Rights Reserved.
+
+ This document and translations of it may be copied and furnished to
+ others, and derivative works that comment on or otherwise explain it
+ or assist in its implementation may be prepared, copied, published
+ and distributed, in whole or in part, without restriction of any
+ kind, provided that the above copyright notice and this paragraph are
+ included on all such copies and derivative works. However, this
+ document itself may not be modified in any way, such as by removing
+ the copyright notice or references to the Internet Society or other
+ Internet organizations, except as needed for the purpose of
+ developing Internet standards in which case the procedures for
+ copyrights defined in the Internet Standards process must be
+ followed, or as required to translate it into languages other than
+ English.
+
+ The limited permissions granted above are perpetual and will not be
+ revoked by the Internet Society or its successors or assigns.
+
+ This document and the information contained herein is provided on an
+ "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
+ TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
+ BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
+ HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
+ MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+
+Acknowledgement
+
+ Funding for the RFC Editor function is currently provided by the
+ Internet Society.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Crispin Standards Track [Page 7]
+\f
projects / uw-imap / commitdiff