Edit Wp-mail.php?

Hello,

I recently moved to a dedicated server and as soon as I did that my contact form notifications stopped coming to us. I am using Gravity Forms and can log in to the admin section and see the entries but I am not receiving email notifications. I contacted the Gravity Forms and have spoken to my hosting support. It seems that I need to configure my script on the form to use the relay server, dedrelay.securserver.net. Since gravity forms uses the wordpress email function I am assuming it is the wp-mail.php file that needs to be edited.

Can someone tell me if I am correct in thinking the wp-mail.php file that needs to be edited? And if so, can someone tell me which pieces of code need to be edited?

Thanks for any help