Here is the scenario:
I have 2 Exchange 2003 Servers in my domain: MyCompany.com.
We also have a subsidiary company (with different name: ABC.com) operating within the same building and connected to our network. However, their email is being hosted by an outside company and forwarded to @MyCompany.com (our email system).
They have numerous problems with their email system, so they want us to host/manage their email, but no as @MyCompany.com, but as theirs, @ABC.com.
How do I setup one of my exchange servers to host/handle their emails separately as @ABC.com and not as @MyCompany.com, so they can receive and send emails as ABC.com?