RFC 5464 - The IMAP METADATA Extension RFC 5258 - Internet Message Access Protocol version 4 - LIST Command Extensions RFC 5257 - Internet Message Access Protocol - ANNOTATE Extension RFC 5256 - Internet Message Access Protocol - SORT and THREAD Extensions RFC 5255 - Internet Message Access Protocol Internationalization RFC 5182 - IMAP Extension for Referencing the Last SEARCH Result RFC 5162 - IM