a working model

1. Choose your MTA

   We chose exim - flexible, readable config. Others like postfix or sendmail

2. Consider in-MTA greylisting

   If not using PF + spamd, a milter (sendmail, greylist-milter) or policy server (postfix - postgrey) is an option.

3. Choose your malware scanner

   We chose clamav - free (GPL), quick database update. Others available, free and commercial

4. Choose your spam filtering

   We chose spamassassin - free, flexible, active development.

   Others like dspam others (free or commercial)

spamassassin offers feedback to hashlists (this message is spam) such as Razor, DCC - a few scripts will go a long way

All this used to be unneccessary :(