Why do manual changes to /etc/postfix/main.cf and /etc/postfix/master.cf get reverted on a Plesk server?

Question

Customized entries in
/etc/postfix/main.cf and
/etc/postfix/master.cf get reverted after running the plesk repair mail command, installation of Plesk microupdates, changes made in Plesk GUI > Tools & Settings > Mail Server Settings or after starting to use the Plesk Email Security extension. Why do these changes get reverted?

Answer

These Postfix configuration resets are intended and Plesk functionality depends on them happening.

Plesk rewrites the Postfix config files if corresponding mail settings are changed and it needs to be able to do so in order to deliver a consistent and well-functioning mail configuration.

The Plesk Email Security extension requires almost constant access to these configuration files in order to deliver consistent results as well.

Postfix configuration files will also often be regenerated during any Postfix package updates.

You may vote for the feature request of keeping Postfix customization files untouched by Plesk on the following link:

Allow customization of /etc/postfix/main.cf and /etc/postfix/master.cf – Your Ideas for Plesk

Top-ranked suggestions are likely to be included in future versions of Plesk