33.3 Postfix Pre-Installation Steps

The first step before installing Postfix is to make sure that Sendmail is not already running on your system. You can check for this using the following command:

# systemctl status sendmail

If sendmail is not installed, the tool will display a message similar to the following:

Unit sendmail.service could not be found.

If sendmail is running on your system it is necessary to stop it before installing and configuring Postfix. To stop sendmail, run the following command:

# systemctl stop sendmail

The next step is to ensure that sendmail does not get restarted automatically when the system is rebooted:

# systemctl disable sendmail

Sendmail is now switched off and configured so that it does not auto start when the system is booted. Optionally, to completely remove sendmail from the system, run the following command:

# apt remove sendmail