Expertise level: Medium
cPanel & WHM version 11.40
Spammers commonly attempt to work around mail security settings by interacting directly with remote mail servers. WHM's SMTP Restrictions can prevent users from doing so. You can access this feature in two locations:
- Home >> Server Configuration >> Tweak Settings, under the Mail Tab as Restrict outgoing SMTP to root, exim, and mailman.
- Home >> Security Center >> SMTP Restrictions
Enabling this setting restricts outgoing email connection attempts to the mail transfer agent (MTA), the mailman system user, and the root user. Ultimately, this forces both scripts and users to use Exim's Sendmail binary, rather than directly accessing the socket.
NOTE: Prior to version 11.32, this feature would simply block any attempt to connect to a remote mail server. Starting with cPanel & WHM 11.32, the software redirects the outgoing connection attempt to the local mail server.