Red Hat Training

A Red Hat training course is available for Red Hat Enterprise Linux Disable Postfix Network Listening

By default, Postfix is set up to only listen to the local loopback address. You can verify this by viewing the file /etc/postfix/
View the file /etc/postfix/ to ensure that only the following inet_interfaces line appears:
inet_interfaces = localhost
This ensures that Postfix only accepts mail messages (such as cron job reports) from the local system and not from the network. This is the default setting and protects Postfix from a network attack.
For removal of the localhost restriction and allowing Postfix to listen on all interfaces the inet_interfaces = all setting can be used.