Exim Configuration Manager
1. Login to WHM control panel
2. Goto Main >> Service Configuration >> Exim Configuration Manager
3. Enable RBL filtering by Basic Editor >> RBLs >> switch to – On and if you like you may additional RBL from manage option.
4. Sender Verification Callouts = ON {Personally I disabled this option as it was introduced as a feature in the mail server to arrest inbound spamming – Inbound spam can be tolerated to some extent}.
5. Sender Verification = ON
5. Reject SPF failures =ON
6. Then save all the configuration settings.
Configurations in Tweak Setting
1. Login to WHM control panel by using root user
2. Goto Main >> Server Configuration >> Tweak Settings
3. Initial default/catch-all forwarder destination = Fail
4. Max hourly emails per domain = 200
5. Count mailman deliveries towards a domain
After This Also Enable Greylisting
