The IESG has approved “IMAP UNSELECT command” as a Proposed Standard.
This document has been reviewed in the IETF but is not the product of an IETF Working Group.
This document defines an UNSELECT command that can be used to close the current mailbox in an 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 an invalid argument or reselecting the same mailbox with EXAMINE command), a more clean solution is desirable.
http://www.ietf.org/internet-drafts/draft-melnikov-imap-unselect-01.txt