Tony Finch wrote:
On Sun, 18 May 2008, ned+ietf-smtp(_at_)mrochek(_dot_)com wrote:
Another issue is that if you do this sort thing you absolutely must
distinguish between submission and relay somehow, and lots of places are
unable to make such distinctions. It's one thing to force a automatic
relay to retry the second and subsequent recipients of a message, quite
another to force some random user to resubmit the message over and over
in order to get it through.
This kind of problem makes me think there's not much benefit to rejecting
messages at SMTP time from trusted clients, whether they are MUAs or MTAs.
Very much agreed! However, while SMTP AUTH clearly identifies trusted
MUAs, a "trusted MTA" is a somewhat fuzzy concept...