http://www.rfc-editor.org/rfc/rfc3502.txt
RFC 3502: Internet Message Access Protocol (IMAP) - MULTIAPPEND Extension, M. Crispin2003-03-01T23:00:00-00:00This document describes the multiappending extension to the Internet Message Access Protocol (IMAP) (RFC 3501). This extension provides substantial performance improvements for IMAP clients which upload multiple messages at a time to a mailbox on the server. A server which supports this extension indicates this with a capability name of "MULTIAPPEND". [STANDARDS-TRACK]