Fastmail does this thing where it uses a global set of filter rules for everyone, and then after you've spammed/unspammed something like 150 messages, it switch

Fastmail does this thing where it uses a global set of filter rules for everyone, and then after you've spammed/unspammed something like 150 messages, it switches to a more personalized ruleset based on the spam you actually get. I wager I get one, maybe two spam messages in my inbox per month (out of hundreds captured), and maybe one or two false positives in my entire couple years of having mail there. In any case, that's a better record than Gmail - they've got a huge issue with directing legitimate mail into the spam can.