Seems pretty trivial to me. 1) install spamassassin 2) turn on greylisting During if you want to to from 1-2 spam a day to 1-2 a month you might want to block

Seems pretty trivial to me. 1) install spamassassin 2) turn on greylisting During if you want to to from 1-2 spam a day to 1-2 a month you might want to block the garbage domains like click, link, party, top, webcam, xyz, stream etc. Probably worth enabling a DNS based block list. So an apt get or two, 2-3 lines in a config file. Seems trivial to me, most every mail server HOWTO mentions them, should be just a cut/paste. Sure 9-12 months from now it won't work as well, thus updating SA periodically, just like anything else internet facing.