--On Wednesday, October 26, 2011 22:43 +0800 Tim Kehres
<tim(_at_)kehres(_dot_)com> wrote:
I've mentioned this to Hector directly, but my feeling is that
while an SMTP extension can be useful, I think tying it to
Greylisting is a bad idea. If what we're looking for is a way
within a SMTP response to indicate a retry time for the
sending MTA, this can and SHOULD be a generic specification
and not one tied to a single application. Something along
the lines of what is in the Atkins proposal seems more
reasonable to me
(http://datatracker.ietf.org/doc/draft-atkins-smtp-traffic-con
trol/).
While it might not help significantly, something more generic
would at least slightly and temporarily lower the odds of a
different problem. I really worry about saying to the spammer
"this site does greylisting" and, if that happens enough, having
the spammer respond (internally) "ah, it is greylisting and not
some random temporary server unavailability, we know what to do
about that".
Independent of what advantages it offers people who are trying
to cooperate in sending legitimate mail, to paraphrase Paul
Vixie, giving spammers the information they need to become
smarter and the incentives to do so are really not in our
long-term best interests.
I have other doubts about both proposals but, if we are going to
move forward with either, I think we need to understand and
consider the tradeoffs very carefully.
john