Billy Gorbachev’s options:
- OpenBSD. Eliminates need for fail2ban, since pf has this functionality built in.
- qmail, not Postfix.
- OpenBSD spamd, not Postgrey. spamd hurts spammers more, and hurts legit senders less. logs are hilarious, e.g. 184.108.40.206: disconnected after 3995 seconds. lists: spamd-greytrap
- Replace spamassassin with Spamhaus hooks in qmail (tcpserver).
- qmail-pop3d, not Dovecot. Dovecot has a poor security track record. Download mail over (pop3 over CurveCP), using fetchmail + CurveCP command-line tools. Store locally in Maildir, backup as necessary/desired.
- drop ClamAV and Amavisd. Run FreeBSD or OpenBSD on your desktop.
- Add GnuPG to your local mail client.
- Add Spamhaus DROP and eDROP to network edge pf tables http://www.spamhaus.org/drop/
- Add a TXT SPF record for your domain, including your servers, followed by “-all”
Several of these changes can be made (SPF record, DROP, GnuPG) without modifying your existing setup.