Did you set up the advanced spam filtering and then train it on all of your folders? I also set the super-advanced options and changed the thresholds to around 3.0 (instead of the default, which was I think 5.0), which really helped. It's better than when I hosted on gmail, but I'd say 5-10 per day still get through and have to be reported, after about a month on fastmail. That's only a couple of percent, though (scanning my spam folder, I get something like 10-12 per hour, but this is an e-mail address I've had and not hidden at all since 1997).