I had my Apple Mail start beachballing earlier today - finally had to force the computer down (hold power button 5 seconds) because Mail would not quit and could not be force-quit - following that, Spamsieve crashes (or Apple Mail crashes while calling SpamSieve plugin - depends on how you look at it I guess) every time I try to train a new Good or Bad message. When I hit ^S to train, I get the beachball for 2 to 3 seconds, then it crashes. I have rebuilt all mailboxes, uninstalled and reinstalled SS twice (removed all /Library and plugin files each time, plus preferences, and reset the corpus - so it asked for my SS key again). I’m going to remove SS temporarily until I can get an idea what I might do. I have two stack traces from the earlier failures if they would help you determine what I might do (or whether there’s a bug in SS). Mac OSX 10.6.7 and SS 2.8.5 on MacBook Pro.
P.S. SS also crashes when I send a message. I don’t see the connection, but it does.