Hi,
Since saturday we are running postfix (current; from backports.org) instead of exim.
The first thing I did after making sure it runs was to add a greylisting daemon. As far as I can tell from wathcing the logs, that is all really having an effect in reducing spam.
Finally, I despammed admin. That is, I downloaded the mbox, and separated the spam from the ham. I don't know how people feel about it[1] - personally I don't mind. I put the old private and public mbox archives in a tar file in ~root/attic.
Now, there are lots of mailing lists on cl.net which essentially are spam traps. How do you feel about weeding the spam out with some automatic tool like spamasassin? It would probably include a few false positives....
Regards, Mario
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[1] Is anybody listening? :-)