Help with webserver emails not sending.

I have a few domains hosted on my CentOS 7 webserver running WHM an Cpanel. I setup my emails, example@[login to view URL] and sent a few test emails. The emails are getting stuck in the queue and not sending. When I try to manually select the message in WHM and click "Deliver Selected" it just times out when sending to the recipient mail server. After doing some research, I may need so setup a PRT record which I tried to do and is not working. I can give access over Teamviewer as this is a high security server.