Network Working Group A. Melnikov Request for Comments: 3691 Isode Ltd. Category: Standards Track February 2004
Internet Message Access Protocol (IMAP) UNSELECT command
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.
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Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document defines an UNSELECT command that can be used to close the current mailbox in an Internet Message Access Protocol - version 4 (IMAP4) session without expunging it. 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 a nonexistent mailbox name or reselecting the same mailbox with EXAMINE command), a more clean solution is desirable.
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 a nonexistent mailbox name 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.
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".
"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].
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
The following syntax specification uses the Augmented Backus-Naur Form (ABNF) notation as specified in [ABNF]. 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.
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.
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