Script to Restrict Communication between two domains

[himanshunegi1986]

Hi,

I need your help in restricting email communication between two domains only for ex: xyz.com and abc.com

xyz.com mail server is hosted on the internet and abc.com is hosted on mail enable enterprise premium edition within my LAN.

Now I want that abc.com should send and receive mails only to xyz.com and abc.com.

abc.com should not be able to send and receive mails from any other domain. How do I attain this?

Kindly provide assistance on the same.

Thanks in advance.