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This document describes the URLAUTH extension to the Internet Message Access Protocol (IMAP) (RFC 3501) and the IMAP URL Scheme (IMAPURL) (RFC 2192). This extension provides a means by which an IMAP client can create “signed” URLs carrying authorization to access limited message data on the IMAP server.
http://www.ietf.org/internet-drafts/draft-crispin-imap-urlauth-05.txt