I am not sure if this is in the correct area but here it goes.

Because my isp has blocked their smtp and cannot be used for external email programs, I want to be able to piggy back off my cpanel server to send outgoing email (smtp). At times I get an error and it does not allow the mail to be sent.
Any help on this is greatly appreciated to get this working correctly.

eg:

pop : mail.my-isp-provider.com
smtp: smtp.my-cpanel-server.com

You can try running another instance of Exim on port 26 and change your email program to use that alternate port (if it allows you).

You can do this and even change the port under "Service Manager" from within WHM.