Dspam filters spam with the best. In my installation, it stops over 98% of all spam: I’ve only had one false positive in the last year, and that was a message to the Dspam list that contained a real spam!
Administering Dspam is a breeze. No rules to configure, new users can automatically benefit from a global dictionary and quarantine management is simple. But getting a Dspam quarantine set up the first time, without losing any email, can challenge the most seasoned mail administrators.