Article ID: 5801, created on Apr 22, 2012, last review on Aug 12, 2014

  • Applies to:
  • Plesk for Linux/Unix
  • Plesk 12.0 for Windows


There are two Message Transfer Agents (MTA) that are supported by Parallels Plesk Panel since version 9, including Qmail and Postfix. Each time, only one of them is used by Parallels Plesk Panel.
The MTA that is currently used by Parallels Plesk Panel is shown on the Services management page at Home -> Services Management:

SMTP Server (Postfix)


SMTP Server (QMail)

It is also possible to check the MTA using the Parallels Plesk Panel utility mailmng:

~# $PRODUCT_ROOT_D/admin/sbin/mailmng --features | grep SMTP_Server
$features['SMTP_Server'] = "Postfix";
$features['SMTP_Server_package'] = "postfix";


~# $PRODUCT_ROOT_D/admin/sbin/mailmng --features | grep SMTP_Server
$features['SMTP_Server'] = "QMail";
$features['SMTP_Server_package'] = "psa-qmail";


You can switch the MTA from Qmail to Postfix and back using an autoinstaller script.

Run the script without parameters

~# /usr/local/psa/bin/autoinstaller

and select Parallels Plesk Panel 9 (currently installed) on the fourth page. Disable all other applications like SSO and Sitebuilder.

On the Main components list for Plesk page, select Qmail or Postfix mailserver and click Enter to complete the installation.

Alternatively, you may run the following command to switch MTA to Postfix:

~# /usr/local/psa/admin/sbin/autoinstaller --select-release-current --install-component postfix

and the following command to switch to Qmail:

~# /usr/local/psa/admin/sbin/autoinstaller --select-release-current --install-component qmail

Additional information

The location of the directory where email messages are stored ($PLESK_MAILNAMES_D) and the mail format is not changed when the MTA is switched.
Old mail messages remain unchanged and they are available.

However, the mail queue is reconfigured while switching the MTA and all messages that are still in the queue are lost.
Before switching, it is recommended that you stop the SMTP service to prevent accepting emails and also deliver all queued mail.

By using the following command, you may stop the SMTP service:

~# /usr/local/psa/admin/sbin/mailmng --stop-smtpd

To flush the queue, use the following commands:

QMail MTA:

~# kill -ALRM `pidof qmail-send`

Postfix MTA:

~# postqueue -f

a914db3fdc7a53ddcfd1b2db8f5a1b9c 56797cefb1efc9130f7c48a7d1db0f0c 29d1e90fd304f01e6420fbe60f66f838 ed7be2b984f9c27de1d2dc349dc19c6d 85a92ca67f2200d36506862eaa6ed6b8 a766cea0c28e23e978fa78ef81918ab8

Email subscription for changes to this article
Save as PDF