Adding multiple alternative SMTP Port in cPanel

By default, cPanel only support one additional alternative SMTP port. However, if you need multiple port, follow the steps below:

1) Disable “exim on another port” in WHM -> Service Manager
2) Go to WHM-> Exim Configuration Editor -> Advanced Editor -> at the first text box, add in “daemon_smtp_ports = 25 : 26 : 587″ without “”.
3) Save.