-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org
[mailto:ietf-dkim-bounces(_at_)mipassoc(_dot_)org] On Behalf Of Dave CROCKER
Sent: Monday, September 27, 2010 11:40 AM
To: DKIM List
Subject: Re: [ietf-dkim] Corner cases and loose ends, was ,
draft-vesely-dkim-joint-sigs
It's been a significant revelation, for me, to realize how common it is
for DKIM
processing to occur during the SMTP session.
I think, as Mark points out, this is often an artifact of the constraints of
the existing environment (in our case, the architecture of milter) rather than
a decision that doing so during the SMTP session is obviously the right way to
do it.
That said, there's a lot of agreement that filtering during SMTP is better than
accept-and-then-deal-with-it approaches. (cf. RFC5451, Appendix C)
Unfortunately post-DATA rejection is the only way that can be done, short of
changes to SMTP in the way of yet another extension that wouldn't receive wide
adoption in the short term anyway.
So SMTP issues reduce to finding ways of preventing the cross-net
transfer of
data or even of preventing the SMTP session. Oddly, I think the latter
is more
feasible than the former.
This is probably one of the main reasons SPF remains in widespread use. That
no workable envelope-level DKIM equivalent has materialized to date is
unfortunate.
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