“In order to use BlackBerry, POP3 needed to be used.” From that statement, I think that you are NOT using a Blackberry Enterprise Server? So, why not?
If you want to go the POP route, follow the procedures outlined in the Blackberry device documentation. And you will have to enable the POP task on your server, make it available through your firewall, and change your Notes Mail file to be “POP compatible.”