"Introduction The [SORT] extension to the [IMAP] protocol provides a means for the server-based sorting of messages. It defines a set of sort criteria and the mechanism for determining the sort value of a message for each such ordering. The [SORT] FROM and TO orderings sort messages lexically on the [IMAP] addr-mailbox of the first address in the message's From and To headers@ respectively. This document provides two alternative orderings@ DISPLAYFROM and DISPLAYTO@ which sort messages based on the first From or To address's [IMAP] addr-name (generally the same as its [RFC5322] display-name)@ when present. A server that supports the full [SORT] extension as well as both the DISPLAYFROM and DISPLAYTO sort criteria indicates this by returning ""SORT=DISPLAY"" in its CAPABILITY response."
RFC 5957-2010 history
2010RFC 5957-2010 Display-Based Address Sorting for the IMAP4 SORT Extension (Updates: 5256)