Re: [exim] Reducing Spam Assassin Load

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Author: Alun
Date:  
To: exim-users
Subject: Re: [exim] Reducing Spam Assassin Load
Marc Perkel <marc@???> said, in message
433FF09F.1000501@???:
>
> But no one has done anything to reduce load processing ham.


Here's what we do. If I send mail to marc@???, my exim drops
an entry in a database (auj@???, marc@???). Any mail
from marc@??? to auj@??? is whitelisted on the basis
that we've already swapped mails, and so doesn't go through
out spam filters.

I thought this would be more effective than it is, but when it comes
down to it, only about 1.2% of inbound mail gets matched by this one
(bad time of year to get statistics though - we have lots of new users
at the start of the academic year, so the numbers won't stabilise for a
few weeks). 25% of mail going through SpamAssassin (after our greylist)
comes out as spam, so it's currently saving 1.6% of our SpamAssassin load.

Not a massive saving, but it's a very simple, quick test and is very
unlikely to let spam through and, depending on your user profile,
could be much more effective.

You could take it a lot further and allow marc@??? to e-mail any
address@??? on the basis that someone here has mailed him. I choose
not to do that, but it might up the percentages significantly.

Cheers,
Alun.

-- 
Alun Jones                       auj@???
Systems Support,                 (01970) 62 2494
Information Services,
University of Wales, Aberystwyth