Setting the MX Records for a Local Server

Hello,

I am working for a client in which we installed WordPress on a local server.

That server is behind a firewall and so it is accessed at two different IP addresses for those externally and users who are behind the firewall.

They are having issues with the forms not being emailed properly. They are going to some external third party email address such as sample@yahoo.com but they are not being delivered to sample@examplesite.com

Any suggestions on how to solve this issue?

The IT person is not very familiar with cpanel but did send this message:

I’m no cPanel expert but in the mail troubleshooter the MX record is pointing to mail.sample.edu at XX.XX.XXX.XX this is incorrect.
1. XX.XX.XXX.XX is the external address of our Mail forwarder (Barracuda). The internal address should always be used YYY.YYY.Y.YYY
2. Mail.sample.edu on our internal DNS is set to our spam filter or Barracuda server. I have this set as our primary front end mail forwarder. In other words all e-mails coming into the campus come here, are filtered for virus and spam, then get forwarded to the Exchange server. All outgoing e-mails from Outlook go to the Exchange server then get forwarded to the Barracuda server.
3. Unless cPanel works some magic XX.XX.XXX.XX is not accessible to that server or any other workstation/server on campus as it is an external address. This should be set to the internal address of YYY.YYY.Y.YYY (email.sample.edu or Exchange server) and use the username and password I supplied yesterday because our Exchange server does require authorization.
4. Seeing that cPanel has mail.sample.edu pointing to an non-accessible address which creates a conflict with an established host on our internal network, it will cause issues.