The optional access table directs the Postfix SMTP server to selectively reject or accept mail. Access can be allowed or denied for specific host names, domain names, networks, host addresses or mail addresses.

E-mail address mappings

- `user@domain` matches the specified mail address
- `domain.tld` matches domain.tld as the domain part of an email address
- `user@` matches all mail addresses with the specified user part

Hostname/IP-address mappings

- `net.work.addr.ess
  net.work.addr
  net.work
  net` matches the specified IPv4 host address or subnet-work
- `net:work:addr:ess
  net:work:addr
  net:work
  net` matches the specified IPv6 host address or subnet-work

Action on matches

- `OK` Accept the e-mail.
- `REJECT [message]` Reject the e-mail, and reply with a [message] or a generic error.
- `DISCARD [message]` Silently discard the e-mail; optionally write a [message] log.
- `REDIRECT spam@yourdomain.com` forward the e-mail to another address