This document specifies a message header field called Authentication- Results for use with electronic mail messages to indicate the results of message authentication efforts. Any receiver-side software@ such as mail filters or Mail User Agents (MUAs)@ can use this header field to relay that information in a convenient and meaningful way to users or to make sorting and filtering decisions.
RFC 7001-2013 history
2013RFC 7001-2013 Message Header Field for Indicating Message Authentication Status