Linux Mail Server Setup and Howto Guide

Hi expert,

hope u do well,

I have a real time scenario. I have a corporate office at chicago and we have  a  branch office at dallas. When ever i send an email   to persons at branch office  from branch office  It usually goes to corporate office then delivers to branch office. What i wanted is I need to establish a  local branch office mail server so that to and from branch office mails are to be delivered internally and when i send any mails to corporate office persons it should go to corporate  office alone.But the mail domain name should be the same in the name of the companay eg. mail.abc.com.

Pl provide a  solution for this.

thanx in advance