I've had FastMail about a year, and have yet to get enough spam (200 messages) to trigger their personalized spam filter. Despite the address being signed up... everywhere. The non-personalized ranking system uses common spam ranking services out there, and scores emails about as well as you'd expect from the average corporate spam filter.
FastMail's data collection of your email for their own use is incredibly, incredibly limited, so a lot of things other providers use won't really work for FastMail.
