Plesk notifications are not sent: Postfix is running with backwards-compatible default settings

Symptoms

• Notifications which are set up in Plesk in Tools & Settings > Notifications are not sent.

• When a notification should be sent, Postfix service is terminated with the signal 15 and restarted.

• The following records can be found in the file /var/log/maillog:

  CONFIG_TEXT: postfix[54992]: Postfix is running with backward-compatible default settings
  ...
  plesk postfix/master[32815]: terminating on signal 15
  plesk postfix[55085]: Postfix is running with backwards-compatible default settings
  plesk postfix[55085]: See http://www.postfix.org/COMPATIBILITY_README.html for details
  plesk postfix[55085]: To disable backwards compatibility use "postconf compatibility_level=2" and "postfix reload"
  plesk postfix/master[55122]: /etc/postfix/master.cf: line 123: using backwards-compatible default setting chroot=y
  plesk postfix/master[55122]: /etc/postfix/master.cf: line 125: using backwards-compatible default setting chroot=y
  plesk postfix/master[55122]: daemon started -- version 3.1.0, configuration /etc/postfix

Cause

Postfix is running in the backward-compatible mode.

Resolution

1. Connect to the server using SSH.

2. Add the following line to the file /etc/postfix/main.cf:

   CONFIG_TEXT: compatibility_level=2

3. Reload Postfix configuration:

   # service postfix reload