The home-grown spam filters I’ve been using have a success rate of approximately 75% with a false positive rate of about 10%. Not the best stats — I think we can do better.
In order to continue combating the increasing amount of spam being received, I’ve installed and configured SpamAssassin™ in addition to my current filters. It’s currently running in Identify and Mark mode. Once I’m happy with the results, I’ll set it to quarantine the spam instead.
So far SpamAssassin™ has been 99% accurate. Only one spam message made it into my inbox and it was relatively trival to feed it back to SpamAssassin to teach it that it was spam. So far there have been ZERO false positives.