Hi Mike, At 11:44 25-06-10, MH Michael Hammer (5304) wrote: >And the rest of the world has the disadvantage of only knowing what is >written in the RFC. There is thread about the word at http://mipassoc.org/pipermail/ietf-dkim/2008q1/009572.html The authoritative answer is in Section 4.2.1 of RFC 5617. Regards, -sm