Re: (Not) Possible New Mechanism Prefix

On Tue, 29 Jun 2004 10:15:41 -0700, Jonathan Gardner wrote
> I see your point very clearly now. It sounds like Meng and others 
> really do want an SPF PASS to mean the message is authentic, not 
> just the MTA being an authorized server.
I don't see how SPF can possibly guarantee it.  It can prove the converse (if
there isn't a PASS, it's a forgery) but to prove authenticity, you need
something like PGP or S/MIME.