SoonDead
commented
10 years ago I heard very good things about this from the wordpress community. It's very clever and actively maintained, filters nearly every spam with very few false positives.
A very basic autoban feature without any supervision would be sufficient at first.
- User with less then X post comments something spammy.
- Ban user.
Later a little more sophisticated solution could be developed where moderators can unspam posts and banned users can appeal in some way.
The spam problem is a real pain in the ass. Akismet is pretty damn good at filtering out the crap, so it might be good to run new user's posts through it until they've got 5-10 good ones.