Those are the directions I used to setup an almost complete OpenSource Mail server running NetBSD and pkgsrc.
The Mail server will feature:
- E-mail exchange (MX) role on the Internet;
- E-mail gateway (SMTP) for internal LAN users ;
- E-mail access (IMAP) for internal LAN users ;
- Secured (TLS and SASL) access for internal users;
- Greylisting, RFC check and RBL mail filtering ;
- Directory (LDAP) for e-mail entries ;