I have always self-hosted my mail. When spam started to become an issue I began looking around for a solution. I happened upon the newly minted spamassassin pro

I have always self-hosted my mail. When spam started to become an issue I began looking around for a solution. I happened upon the newly minted spamassassin project, made it work to my liking, sent in a few patches and never looked back. Now, many years later, I still run SA in combination with Exim and Dovecot, filing unrecognised spam into a 'SPAM-it' folder from where it is picked up every night to train the bayes filter. Everything which is 'definitely' spam is refused at the gate, everything which is most certainly spam is filed in a spam folder which is out of sight and mostly out of mind, everything which is probably spam is automatically dumped in the aforementioned 'SPAM-it' folder (with autolearning disabled to avoid erroneous positive feedback). There is a 'HAM-it' folder to tell the filter about mail I care about as well as a 'FORGET-it' folder to untrain the filter on given messages. I use sieve to file messages in their designated folders. No other filtering is applied, no greylisting, no country blocks (I need to be able to communicate with people all over the world), no fail2ban, no nothin'. By keeping the filtering concentrated in one spot I avoid the trap of turning the mail system into a Rube Goldberg machine loaded with unintended consequences. On average, one or two spammy messages make it through the portcullis per day. I simply dump them in the 'SPAM-it' folder and forget about them. False positives are exceedingly rare, fortunately. On the whole I consider my mail setup to be functional and above all manageable. Everything needed to implement this is available in Debian. There is a handy Sieve editor available as a plugin to the Roundcube web mail client for those who like to click pretty boxes instead of writing filter scripts.