Disabling SMTP Tweak – cPanel

The SMTP tweak will prevent users from bypassing the mail server to send mail (this is a common practice used by spammers). It will only allow the MTA (mail transport agent), mailman, and root to connect to remote SMTP servers.  In order words, users will need to use ‘localhost’ as their SMTP server for local mailing scripts to sent mail (source).  SMTP Tweak can be enabled or disabled in the ‘Security Center’ of WHM, or from command line using:

/scripts/smtpmailgidonly on|off

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