I am trying to setup a DNS record pointing to my email server to help out my Sonicwall Email Security 300 appliance. It seems the sonicwall wants to send out NDR's to my exchange server but it is using the MX record to do so which points to my external IP address. This cannot be changed. The end result is NDR's that don't get delivered.
What I thought of was to create a DNS record that the sonicwall could use internally but I'm not sure how to accomplish this with the way DNS is setup. Here is some generic info on my domain and DNS setup. If more is needed please let me know.
External Domain Name: domain.org
Internal Domain Name: domain.lan
Record Sonicwall is looking for: mail.domain.org