Postfix Overview - Introduction - SCN Research

Postfix Configuration - UCE Controls
See generic restrictions.
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Recipient address restrictions
The smtpd_recipient_restrictions parameter restricts what recipient addresses this system accepts in RCPT
TO commands.
Default:
smtpd_recipient_restrictions = permit_mynetworks, check_relay_domains
By default, the Postfix SMTP server relays mail:
• from trusted clients whose IP address matches $mynetworks,
• from trusted clients whose hostname matches $relay_domains or a subdomain thereof,
• from untrusted clients to destinations that match $relay_domains or a subdomain thereof, except for
addresses that contain sender-specified routing (user@elsewhere@domain).
In addition to the above, the Postfix SMTP server by default accepts mail for which Postfix is the final
destination:
• to destinations that match $inet_interfaces,
• to destinations that match $mydestination,
• to destinations that match $virtual_maps.
Syntax:
Specify a list of zero or more restrictions, separated by whitespace or commas. Restrictions are
applied in the order as specified; the first restriction that matches wins.
In addition to restrictions that are specific to recipient mail addresses, you can also specify restrictions
based on the sender mail address, on the information passed with the HELO/EHLO command, and on the
client hostname or network address.
Example:
smtpd_recipient_restrictions = permit_mynetworks, reject_unauth_destination
Note: you must specify at least one of the following restrictions: reject, check_relay_domains or
reject_unauth_destination. Postfix will refuse to receive mail otherwise.
Restrictions:
check_relay_domains
Permit the request when one of the following is true:
• the client hostname matches $relay_domains or a subdomain thereof,
• the resolved destination address matches $relay_domains or a subdomain thereof, and the
address contains no sender-specified routing (user@elsewhere@domain),
• Postfix is the final destination: any destination that matches $mydestination, $inet_interfaces
or $virtual_maps.
Otherwise reject the request. The relay_domains_reject_code parameter specifies the response
code for rejected requests (default: 554).
permit_auth_destination
Ignore the client hostname. Permit the request when one of the following is true:
• the resolved destination address matches $relay_domains or a subdomain thereof, and the
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