http://www.rfc-editor.org/rfc/rfc6541.txt
RFC 6541: DomainKeys Identified Mail (DKIM) Authorized Third-Party Signatures, M. Kucherawy2012-02-01T23:00:00-00:00This experimental specification proposes a modification to DomainKeys Identified Mail (DKIM) allowing advertisement of third-party signature authorizations that are to be interpreted as equivalent to a signature added by the administrative domain of the message's author. This document defines an Experimental Protocol for the Internet community.