system environment/daemons
- amavisd-milter - Milter helper for Amavisd-new
- amavisd-new - Mail virus-scanner
- dansguardian - Content filtering web proxy
- dovecot - Secure imap and pop3 server
- dovecot-mysql - MySQL back end for dovecot
- dovecot-pgsql - Postgres SQL back end for dovecot
- dovecot-pigeonhole - Sieve and managesieve plug-in for dovecot
- opendmarc - DMARC milter and library
- postfix - Postfix Mail Transport Agent
- postsrsd - PostSRSd provides the Sender Rewriting Scheme (SRS) via TCP-based lookup tables for Postfix.
- sks - Synchronizing Key Server
- smf-spf - Mail filter for Sender Policy Framework verification