MX or Mail routing is the configuration that tells your server if it should attempt to accept messages for a domain on the local MX server, or if it should attempt to direct messages for the domain to a remote MX server.
The following procedure outlines how to change the MX or mail routing for a domain in WHM.
1. Login to WHM as the root user
2. Navigate to: Home »DNS Functions »Edit MX Entry
3. Select the domain that you would like to modify and click Modify
4. If mail for the domain should be sent to the server that you're logged into, select Local
5. If mail for the domain should be delivered to a server that is not the local server, select Remote
6. If you want for the local server to store mail and wait for a higher priority MX server to become available for final delivery, select Backup
6. If you want for cPanel to check the MX record of the domain and select the routing for you select, Automatic
7. Unless a change is specifically required, leave the MX records as they are
8. Click the blue Save button