Subject: Re: PCYMTNQREAIYR, it really works.
From: Brian Dessent <[email-masked]>
To: "Gerrit @ cygwin" <[email-masked]>
Date: Thu, 23 Sep 2004 16:44:30 -0700

"Gerrit P. Haase" wrote:

> >> You can filter about hundred mails a day, maybe 250, but since I'm
> >> getting 1000 mails a day and more my machine is quite busy with
> >> filtering.
> 
> > Hell I'm filtering 1000 - 1500 per day and putting them into an SQL
> > database as well as bouncing most of them on my little 333 Mhz Linux box
> > without the CPU dropping below 90% idle.
> 
> I really should install another system... which database are you
> using?  Which program?  I'm interested to do the same, but I have not
> found the all in one solution yet, there is dbmail, but it doesn't
> work with Windows (or Cygwin) yet.

I run spamassassin and clamav during the SMTP DATA phase, thanks to the
exiscan-acl patch (which is included in the exim4-daemon-heavy Debian
package) for every incoming message.  This is on a very modest server
with only 64MB of RAM - a VDS using usermode linux.  I find that most
messages take less than 5 seconds to process, with most taking 1-3
seconds.  Even if each one took 5 seconds, that would still be a
throughput of more than 17k messages per day.

The advantage of doing it this way is that I can reject spam and malware
at SMTP time, with no possibility of generating a bogus non-deliverable
bounce that will just clog up some innocent's inbox.  While the
hard-core spammers aren't phased by the SMTP 5xx reject, some spamware
used by the more grey-hat organizations will actually take note that the
message was rejected and not attempt a retry - which at least saves a
little bit of future bandwidth.  I have a two-level threshold system,
anything that scores above 12.0 spamassassin points gets rejected
outright after the SMTP DATA command, and anything higher than 5.0 gets
the "X-Spam-Flag: YES" header inserted for easy filtering by my mail
application into the spam folder.  I'm very pleased with the results.

Brian

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