On Jun 1, 2005, at 5:25 PM, Chad Leigh -- Shire.Net LLC wrote:
On Jun 1, 2005, at 3:16 PM, Jorn Argelo wrote:
Chad Leigh -- Shire.Net LLC wrote:
On Jun 1, 2005, at 8:07 AM, Bart Silverstrim wrote:
I've been looking into ways of improving our spam filtering.
Currently I'm running postfix with amavisd-new (spamassassin and
clamav), and saw an article on greylisting using postgrey. Turns
out there's a port for it already in FreeBSD.
I don't run postifx and the thing I am about to mention I have not
tried yet, but you may want to explore modifying your greylisting to
be based on spamassassin results.
I use exim as the mta and there is a thing called sa-exim that lets
you run spamassassin at SMTP time so that you can reject mail if you
want before you actually are finished receiving it. The author of
sa- exim has modified it to do greylisting based on spamassassing
scores generated at smtp time, so that you only greylist mail that
is thought to be spam and do not inconvenience your regular users.
Can you do spamassassin at smtp time with postfix?
That's far too complicated. Postgrey does an excellent job.
Yes, normal greylisting works for some people, but in general, it is
not seconds, but minutes (I don't believe that your server tells it
how long to wait, but rather in general greylisting it returns a 4xx
temporary failure error and the sending mail server will automatically
retry within its own retry rules) and lots of people do not like to
have their good mail greylisted at all as it can delay good mail for
minutes or longer, so the one I described above is a modification on
greylisting that allows it to only greylist possible spam and not all
mail.
If I understand the postgrey docs correctly, there is a mechanism where
it'll automatically whitelist common IPs from which mail is accepted,
so the greylisting is more of an adaptation period. But I could be
mistaken and confusing it with another greylist system...
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