Internet Message Access Protocol (IMAP) is for use in building clients and servers for storage, retrieval, and manipulation of electronic mail, which unlike POP3, can serve as a remote file server

• IMAP4 Binary Content Extension - (IETF RFC 3516) provides a mechanism for IMAP4 clients and servers to exchange message body data without using a MIME content-transfer-encoding, Lyndon Nerenberg, April 2003
• The Internet Message Action Protocol (IMAP4) Child Mailbox Extension - (IETF RFC 3348) provides a mechanism for a client to efficiently determine if a particular mailbox has children, without issuing a LIST "" * or a LIST "" % for each mailbox, Mike Gahrns and Raymond Cheng, July 2002
• Internet Message Access Protocol (IMAP) - MULTIAPPEND Extension - (IETF RFC 3502) provides substantial performance improvements for IMAP clients which upload multiple messages at a time to a mailbox on the server, Mark R. Crispin, March 2003
• Internet Message Access Protocol - Version 4rev1 - (IETF RFC 3501, Obsoletes RFC 2060 and RFC 1730) permits manipulation of remote message folders, called "mailboxes", in a way that is functionally equivalent to local mailboxes, and provides the capability for an offline client to resynchronize with the server, Mark R. Crispin, March 2003
• Message Disposition Notification (MDN) profile for Internet Message Access Protocol (IMAP) - (IETF RFC 3503) guidelines for implementers of IMAP4 that want to add essage Disposition Notification (MDN) support to their products, which provides a means by which a message can request that message processing by the recipient be acknowledged as well as a format to be used for such acknowledgements, Alexey Melnikov, March 2003