This weekend I will be pointing all mail to the new Exchange 2010 server and the Exchange 2003 server will be only proxying requests from the 2010 server. I do have a Barracuda anti spam firewall in front of the 2003 server that has the "destination Mail Server" IP as the 2003 server.
Do I need to change this to the 2010 server IP?
I assumed thsi IP was the sending and receiving IP?
Note: mailboxes are still on 2003 server, I just want all the incominga nd outgoing mail routing to go through the 2010 Exchange server so I need to know which IP has to go into the Barracuda.