Actually, [spamd](https://en.wikipedia.org/wiki/Spamd) configured to [blacklist-only](http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man8/...) works quite awesomely. I reduced my spam volume from several dozens a day to no more than a pair a week. I haven't had any loss in legitimate email, or anyone complaining about inapropiate bounces.

I'm actually surprised, since I actually expected more spam to get through.