Re: Is gray-listing a one-shot anti-spam measure?
On Friday 03 December 2004 09.44, Russell Coker wrote:
> accept mail) on a spam-trap will be fine. The Postfix implementation of
> gray-listing postgrey does not send it's 450 code until after the rcpt
> to:,
Just for completeness. Greylisting, as the term was defined in the original
paper, always uses (client IP/envelope sender/envelope rcpt) triples to
block on, so every greylisting implementation needs to wait until RCPT TO
before it can return 450.
postfix and postgrey can, additionally, return '450-if-accepted' which
allows postgrey to be included early in the mail processing (so it adds all
data point to its database), but if a mail would be rejected anyway by a
later restriction (DNSBL, whatever), *that* rejection is the one seen by
clients, and not the one from the greylisting. Note: I'm not really sure
what the benefit is of this - if mail is rejected anyway on a DNSBL or
whatever, there's not much point in adding the data to postgrey's database.
But that's how postgrey works.
(And - this to Stephen Frost, I believe - there is a patch to postgrey which
I will include in the next version, and I believe which will also be
included in the next upstream, to whitelist a client IP as soon as one
greylisted email came through. So the load on legitimate mailservers will
be even smaller.)
greetings
-- vbi
[some people on this list have been cc:ing me in the past. Please don't.]
--
Don't hit the keys so hard, it hurts.
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