I just saw this recently submitted draft and don't recall it being
discussed in the recent spam thread, so thought I'd point it out in
case people hadn't noticed it:
http://www.ietf.org/internet-drafts/draft-danisch-dns-rr-smtp-01.txt
(Note: I am stating no opinion about its applicability or effectiveness)
-- Cos (Ofer Inbar) -- cos(_at_)aaaaa(_dot_)org
http://cos.polyamory.org/
"OSI is a beautiful dream, and TCP/IP is living it!"
-- Einar Stefferud <Stef(_at_)nma(_dot_)com>, IETF mailing list, 12 May
1992