It is really necessary to stop malicious activities and SPAM attacks on cPanel server. There are number of steps but you must need to enable/disable some Tweaks on cPanel server.
1- Setting in “Exim Configuration Manager”
1. Login to WHM control panel by using root login details
2. Go to Exim Configuration Manager
3. Enable RBL filtering by Basic Editor RBLs switch to “On” and if you like you may have additional RBL from manage option.
4. Please turn ON Sender Verification Callouts
5. Please turn ON Sender Verification
5. Please turn ON Reject SPF failures
6. Then save the entire configuration this will stop most of spams in the server.
2- Some changes in Tweak Setting
1. Login to WHM control panel by using root user
2. Go to Server Configuration > Tweak Settings
3. Set “Initial default/catch-all forwarder destination = Fail”
4. Max hourly emails per domain = 200
5. Please turn ON Count mailman deliveries towards a domain’s Max hourly emails
6. The maximum percentage of failed or deferred messages a domain may send per hour = 60%
7. Then save the entire configuration this will help to stop most of spams in the server.
That’all to do.Please Give your opinion below if you experience any issues or to discuss your ideas and experiences.