How can you hardset a specific Exchange Server to connect to?

Hi All,

We are in the process of migrating a recently purchased company into our Organization.

I would like for their Outlook 2010 (from their own domain) to connect specifically to a 2010 Exchange Server in our Domain.

Is there a location either Client-Side or Server-Side (GPO) where I can force the Exchange Server their Outlook 2010 connects to?

I don't see it in the Outlook 2010 ADMX files.  This is all new to me and please talk to me like I'm five.

Thank you very much for your time,

Mr Mister