I inherited this from a previous admin no longer with the company. I have never done what I am about to describe and would like some expert input on what needs to happen to make this go correctly.
MS Server 2003
All mail in / out of the Exchange environment flows through it
MS Server 2008
Non Domain Controller
All mailboxes for the environment
Sends all mail to Exchange 2003 server for delivery
Tasked with retiring Exchange 2003 server. I've never faced this before and would welcome any details from any Exchange admins willing to share what I would need to do here to successfully retire the Exchange 2003 server and take it off line and have the Exchange 2007 server take over all mail service duties.