bsilver at chrononomicon.com
Thu Jun 2 04:52:31 PDT 2005
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
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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