I really struggled with the lack of good documentation and the massive changes with version updates of these superb tools so I've documented my eventual success at: http://www.psyctc.org/Linux-Debian/spam.html for anyone wanting to set up server wide (i.e. not user controllable) antispam in a similar way.
Chris PSYCTC: Psychotherapy, Psychology, Psychiatry, Counselling and Therapeutic Communities; practice, research, teaching and consultancy. Chris Evans & Jo-anne Carlyle http://psyctc.org/ Email: [EMAIL PROTECTED]