How to Enable SMTP Restrictions

SMTP restrictions prevent users from bypassing the mail server to send mail. This feature allows you to configure your server so that the mail transport agent (MTA), Mailman mailing list software, and root user are the only accounts able to connect to remote SMTP servers. In this tutorial, we can discuss how to enable SMTP restrictions via WHM.


To enable SMTP restrictions from WHM, follow the below steps.

1) Login to WHM.

2) Click on the icon ‘Security Center’.

SMTP Restriction


3) Click ‘SMTP Restrictions’.

SMTP Restriction


4) Click the button ‘Enable’.

SMTP Restriction


Now you have successfully enabled SMTP restrictions.


You can also enable SMTP restriction from tweak setting. Follow the below steps to enable SMTP restrictions using tweak settings.

1) Navigate to Home »Server Configuration »Tweak Settings.

2) Click on the tab ‘Mail’. Here you can see the option ‘Restrict outgoing SMTP to root, exim, and mailman’. Change it to ‘on’ mode to enable the SMTP restrictions.

SMTP Restrictions


Error when enabling SMTP Restrictions – cPanel/WHM

When enabling SMTP restriction from WHM you may encounter this error: ”An error occurred attempting to update this setting. The SMTP restriction is disabled”. You can resolve this error via the command line interface.

1) Login to your server via SSH.

2) Run the below command.

 # /scripts/smtpmailgidonly on


Now you have successfully enabled SMTP restrictions.


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