There are 2 Mail servers supported by Plesk and they are Qmail and Postfix, however, only one MTA (Message Transfer Agents) can be installed and used at a time. To check the current MTA in use, look at
Plesk -> Settings -> Services Management
OR you can execute the following command from SSH
# /usr/local/psa/admin/bin/mailmng --features | grep SMTP_Server $features['SMTP_Server'] = "QMail"; $features['SMTP_Server_package'] = "psa-qmail";
Plesk offers an ‘autoinstaller’ script to install/upgrade various components, using
which you can switch from Qmail to Postfix OR
Before you switch, make sure you stop the SMTP service, to avoid accepting of new emails and deliver the emails that are in the mail queue.
Stop the SMTP service:
# /usr/local/psa/admin/sbin/mailmng --stop-smtpd
Switch MTA from Qmail to Postfix:
# /usr/local/psa/admin/sbin/autoinstaller --select-release-current \ --install-component postfix
OR switch MTA from PostFix to Qmail:
# /usr/local/psa/admin/sbin/autoinstaller --select-release-current \ --install-component qmail
One thing to note here is that, the change of mail server won’t change the mail format and the directory location where the messages are stored. However, the emails in the mail queue will be removed since the MTA is reconfigured.