http://www.rfc-editor.org/rfc/rfc6854.txt
RFC 6854: Update to Internet Message Format to Allow Group Syntax in the "From:" and "Sender:" Header Fields, B. Leiba2013-03-01T23:00:00-00:00The Internet Message Format (RFC 5322) allows "group" syntax in some email header fields, such as "To:" and "CC:", but not in "From:" or "Sender:". This document updates RFC 5322 to relax that restriction, allowing group syntax in those latter fields, as well as in "Resent-From:" and "Resent-Sender:", in certain situations.