





Internet Draft: IMAP UNSELECT command                        A. Melnikov
Document: draft-melnikov-imap-unselect-01.txt            MessagingDirect
Expires: November 2003                                          May 2003
Intended category: Standards Track

                         IMAP UNSELECT command

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,
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   A revised version of this draft document will be submitted to the RFC
   editor as a Proposed Standard for the Internet Community.  Discussion
   and suggestions for improvement are requested, and should be sent to
   the IMAPEXT Mailing list <ietf-imapext@imc.org>. Distribution of this
   draft is unlimited.

Copyright Notice

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

   Please see the Full Copyright section near the end of this document
   for more information.

Abstract

   Certain types of IMAP clients need to release resources associated
   with the selected mailbox without selecting a different mailbox.
   While [IMAP4] provides this functionality (via a SELECT command with
   an invalid argument or reselecting the same mailbox with EXAMINE
   command), a more clean solution is desirable.

   [IMAP4] defines the CLOSE command that closes the selected mailbox as
   well as permanently removes all messages with the \Deleted flag set.



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   However [IMAP4] lacks a command that simply closes the mailbox
   without expunging it. This document defines the UNSELECT command for
   this purpose.

   A server which supports this extension indicates this with a
   capability name of "UNSELECT".


Table of Contents

   1.    Conventions Used in this Document............................ 2
   2.    UNSELECT command............................................. 3
   3.    Security Considerations...................................... 3
   4.    Formal Syntax................................................ 3
   5.    Acknowledgments.............................................. 4
   6.    Normative References......................................... 4
   7.    Author's Addresses........................................... 4


1.   Conventions Used in this Document

   "C:" and "S:" in examples show lines sent by the client and server
   respectively.

   The keywords "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
   in this document when typed in uppercase are to be interpreted as
   defined in "Key words for use in RFCs to Indicate Requirement Levels"
   [KEYWORDS].























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2.   UNSELECT Command

   Arguments:  none

   Responses:  no specific responses for this command

   Result:     OK - unselect completed, now in authenticated state
               BAD - no mailbox selected, or argument supplied but
                     none permitted

      The UNSELECT command frees server's resources associated with
      the selected mailbox and returns the server to the authenticated
      state. This command performs the same actions as CLOSE, except
      that no messages are permanently removed from the currently
      selected mailbox.


   Example:    C: A341 UNSELECT
               S: A341 OK Unselect completed


3.   Security Considerations

   It is belived that this extension doesn't raise any additional security
   concerns not already discussed in [IMAP4].


4.   Formal Syntax

   The following syntax specification uses the augmented Backus-Naur
   Form (BNF) notation as specified in [RFC-822] as modified by [IMAP4].
   Non-terminals referenced but not defined below are as defined by
   [IMAP4].

   Except as noted otherwise, all alphabetic characters are case-
   insensitive.  The use of upper or lower case characters to define
   token strings is for editorial clarity only.  Implementations MUST
   accept these strings in a case-insensitive fashion.

   command-select  /= "UNSELECT"











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5.   Acknowledgments

   UNSELECT command was originally implemented by Tim Showalter in
   Cyrus IMAP server.

   Also, the author of the document would like to thank Vladimir
   Butenko and Mark Crispin for reminding that UNSELECT has to be
   documented. Also thanks to Simon Josefsson for pointing out that
   there are multiple ways to implement UNSELECT.


6.   Normative References

   [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", RFC 2119, March 1997.

   [IMAP4] Crispin, M., "Internet Message Access Protocol - Version
   4rev1", RFC 2060, University of Washington, December 1996.


7.   Author's Addresses

   Alexey Melnikov
   ACI Worldwide/MessagingDirect
   Address: 59 Clarendon Road, Watford,
   Hertfordshire, United Kingdom, WD17 1FQ

   Phone: +44 1923 81 2877

   Email: mel@messagingdirect.com





















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Intellectual Property Statement

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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF



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   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.













































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