Freddy
If you are using a pc on the same network as the controller and you were automatically given your ip address by the dhcp server, you can run a command line window and issue the command ipconfig /all. This should show you the dns servers address. Hopefully your PAC will be using the same one.
I too have yet to get this command working with my workplace exchange server. We have a chart that does a direct command interface to the exchange server. Ben posted a script block in the forums here that does exactly that. Send an email from a controller
If you are sending via an exchange server and all else fails, the code Ben posted will get you out of trouble.
I hope this helps