Sylpheed-Claws and spam

I've finally gotten fed up with Thunderbird. Today, I made the switch to Syspheed-claws. Got it configured with very little trouble and imported all my mail with great success. Everything's groovy. One little difficulty I'm having. Claws comes with spamassasin plugin. I enabled both that and the GTK interface which shows up in "Other Preferences". Everything's set up - basically with defaults. My question is... now what? Do I need to have spamassasin daemon running separately, with its own configs and Sylpheed will just ride on top of that? Or am I correct in my understanding that I have to download mail through something like fetchmail, filter it through spamassasin and then have Sylpheed read my local mailbox? And if that's correct, why the devil do I need spamassasin plugins and more importantly, is there a better way?