Linux Mail Server Setup and Howto Guide

Hey,

First off, great tutorial. Simple and easy to implement. Keep up the great work!

Now to the business….I have my new mail server setup now but I'm still having some issues. The company that I am working for right now asked me to do an upgrade of their previous email system. Here is some data to make this easier to explain:

External Domain : mycompany.com

Internal AD Domain : mycompany.local

Old Mail Server: mail.mycompany.com

New Mail Server: iosmail.mycompany.local

Is there anyway to run both email servers with the same domain name ie: slickrick@mycompany.com and get the same email to both systems?

Also how does external MX records deal with two email servers on the same domain if they both of a MX priority of 1?

How can I setup mailboxes for users that are already created in AD?

Also, I am able to send emails from the New Mail Server just whenever I do a reply the Old Mail Server picks the email up.

Any help is appreciated.

Thanks