Need to change SMTP from IP of server to name of server...

So 10.7.3 server, Mail is working, I can send/recieve from the webmail interface fine.

But, when I add the account to Apple's Mail app. I have to put in the IP of the server for SMTP to get it to work. I can't use the servername. I'm not sure if i'm missing something in DNS or the Server settings?

I do have a MX record in the DNS host of the machines name: mini.socialgraphics.com So, when I add the name into the Incoming Mail Server, Apple's Mail is able to recieve messages no problem.

But to send messages from Apple's Mail Client, I have to put in the IP of the server, the machine name won't work.

I know i'm missing something simple.

Thanks!