Wow. I now get over 20,000 spams a month. Maybe that explains why I seem to get a lot more false negatives (spam that gets through) via Spamassassin. It’s the same small percentage as ever, there’s just a lot more of them.
Some spammers are definitely working on evading SA’s filters. I see a lot of spams that pretend to come from Pine and Mozilla simultaneously – scoring them a massive minus twelve on Spamassassin’s anti-spam-o-meter. I’ve tweaked the reward for these tests down a bit in my own user preferences. I’ve also nudged up the penalties for falling foul of SA’s new Razor2 and Bayesian modules. Spamasssassin’s still a bit hesitant to trust these much. But with the amount of spam (and normal mail) I get, my Bayesian filters get all the training they need. Don’t know why it gives Razor such a low score – perhaps Spamassassin’s overly cautious approach to false positives is leading it to punish for accidentally catching some major mailing lists?