SMTP Restrictions is a feature in cPanel and WHM that helps to reduce outbound spam by forcing all SMTP connections through the local Exim server.
If you need to bypass Exim when sending messages via a script, you may need to disable this feature with the following steps.
- Login to WHM as the root user.
- Navigate to: "Home »Security Center »SMTP Restrictions."
- Click the "Disable" button.