1. Login to WHM using root details.
2. Follow WHM >> Service Manager
3. Once you will enter in service manager then search for ‘Exim Mail Server (on another port)’.
4. By default it is set to port number 25. You can enter the port number which you would like to setup now for SMTP connection.
6. Restart the exim service from WHM >> Restart Services >> Mail Server (Exim) >> Are you sure you wish to restart this service? >> Yes.
Make sure the port which you have entered for exim mail server is opened in your server’s firewall.