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