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Versions: 00 01 02 03 04 05 rfc4469                                     
LEMONADE                                                      P. Resnick
Internet-Draft                                     QUALCOMM Incorporated
Expires: June 29, 2004                                 December 30, 2003

       Internet Message Access Protocol (IMAP) CATENATE Extension

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
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   This Internet-Draft will expire on June 29, 2004.

Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.


   The CATENATE extension to the Internet Message Access Protocol (IMAP)
   allows clients to create messages on the IMAP server which may
   contain a combination of new data along with parts of (or entire)
   messages already on the server. Using this extension, the client can
   catenate parts of an already existing message on to a new message
   without having to first download the data and then upload it back to
   the server.

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1. Introduction

   The CATENATE extension to the Internet Message Access Protocol (IMAP)
   [1] allows the client to create a message on the server which can
   include the text of messages (or parts of messages) that already
   exist on the server without having to FETCH them and APPEND them back
   to the server. The CATENATE command works much like the APPEND
   command except that, instead of a single message literal, the command
   can take as arguments any combination of message literals (as
   described in IMAP [1]) and message URLs (as described in the IMAP URL
   Scheme [2] specification). The server takes all of the pieces and
   catenates them into the output message.

   There are some obvious uses for the CATENATE command. The motivating
   use case for this command was to provide a way for a
   resource-constrained client to compose a message for future delivery
   which contains data that already exists in that client's IMAP store.
   Because the client does not have to download and re-upload
   potentially large message parts, bandwidth and processing limitations
   do not have as much impact. (Mechanisms for sending the message are
   outside of the scope of this document.)

   CATENATE can also be used to copy parts of a message to another
   mailbox for archival purposes while getting rid of undesired parts.
   In environments where server storage is limited, a client could get
   rid of large message parts by copying over only the necessary parts
   and then deleting the original message. CATENATE could also be used
   to add data to a message such as prepending message header fields or
   including other data by making a copy of the original and catenating
   the new data.

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2. The CATENATE Capability

   A server which supports this extension returns "CATENATE" as one of
   the responses to the CAPABILITY command.

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3. The CATENATE command

   Arguments:     mailbox name

                  OPTIONAL flag parenthesized list

                  OPTIONAL date/time string

                  one or more message parts to catenate, specified as:

                                 message literal


                                 message (or message part) URL

   Responses:     no specific responses for this command


                  OK -  catenate completed

                  NO -  catenate error: can't append to that mailbox,
                        error in flags or date/time or message text, or
                        can't fetch that data

                  BAD - command unknown or arguments invalid

   The CATENATE command concatenates all of the message parts and
   appends them as a new message to the end of the specified mailbox.
   The optional flag parenthesized list and date/time string are used
   just as they are in the APPEND command, setting the flags and the
   internal date, respectively. The subsequent parameters specify the
   message parts that are appended sequentially to the output message.

   If a message literal is specified (indicated by the octet count
   enclosed in braces), the octets following the count are appended just
   as they would be with the APPEND command. If a message URL is
   specified, the octets of that body part are appended, as if the
   literal returned in a FETCH BODY response were put in place of the
   message part specifier. The CATENATE command does not cause the \Seen
   flag to be set for any catenated body part.

      Note: This document only describes the behavior of the CATENATE
      command using a message URL (as defined by [2]) which refers to a
      specific message or message part in the currently selected mailbox
      on the current IMAP server. (Because of that, the CATENATE command
      is valid in the selected state for purposes of this

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      specification.) Use of a URL that refers to anything other than a
      message or message part from the currently selected mailbox on the
      current IMAP server is outside of the scope of this document,
      would require an extension to this specification, and a server
      implementing only this specification would return NO to such a

   The client is responsible for making sure that the catenated message
   is in the format of an RFC 2822 [3] message. This includes inserting
   appropriate MIME [4] boundaries between body parts if necessary.

   Responses behave just as the APPEND command. If the server implements
   the IMAP UIDPLUS extension [5], it will also return an APPENDUID
   response code in the tagged OK response.

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4. Formal Syntax

   The following syntax specification uses the Augmented Backus-Naur
   Form (ABNF) [6] notation. Undefined elements are defined in the
   formal syntax of the ABNF [6], IMAP [1], and IMAP URL [2]

       catenate    = "CATENATE" SP mailbox [SP flag-list] [SP date-time]
                     1*(SP (literal / imapurl))

                                Figure 1

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5. Security Considerations

   The CATENATE extension does not raise any security considerations
   that are not present for the base protocol or in the use of IMAP
   URLs, and these issues are discussed in the IMAP [1] and IMAP URL [2]

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Normative References

        RFC 3501, March 2003.

   [2]  Newman, C., "IMAP URL Scheme", RFC 2192, September 1997.

   [3]  Resnick, P., "Internet Message Format", RFC 2822, April 2001.

   [4]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
        Extensions (MIME) Part One: Format of Internet Message Bodies",
        RFC 2045, November 1996.

   [5]  Myers, J., "IMAP4 UIDPLUS extension", RFC 2359, June 1998.

   [6]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
        Specifications: ABNF", RFC 2234, November 1997.

Author's Address

   Peter W. Resnick
   QUALCOMM Incorporated
   5775 Morehouse Drive
   San Diego, CA  92121-1714

   Phone: +1 858 651 4478
   EMail: presnick@qualcomm.com
   URI:   http://www.qualcomm.com/~presnick/

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Intellectual Property Statement

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   This document and the information contained herein is provided on an

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   Funding for the RFC Editor function is currently provided by the
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