For those of us who are not large companies where paying another company for spam protection is an option, combatting spam can be something both fun, and annoying. Hopefully, for any newbies, here are some things to do that can greatly reduce the amount of spam you receive, as well as minimize the amount of false positives of mail identified as spam.
Have spamassassin learn ham and spam
Many people I have seen just install spamassassin, run sa-update, then complain that they are getting a ton of spam. Spamassassin needs tuned, and tuning is quite easy. The quick and easy way is with sa-learn.
You MUST train both ham and spam to be effective. I have to use the vscan user, as I run amavis. sa-learn will add the bayesian tokens to the datbase of the user executing spamassassin.
A nice thing to do is to report mail that you have found to be spam. If you have installed the Razmor moudle, it can be reported to Vipul’s Razor. Assuming in a folder that is full of spam:
This perl script can be run as a cron job. Just point it to a folder that contains only spam.
Ensuring you are doing sa-update frequently, as well as the above, will help spamassassin properly identify spam/ham. I am personally just tagging the subject, and putting anything with that tag in the subject into a folder that is just spam, and running the above commands. This, in addition to running postscreen and a few select rbls, has slowed any spam making it to my inbox to a trickle.
Excellent reference: http://www.spamtips.org/p/ultimate-setup-guide.html