I have an existing 2003 AD domain with a single Exchange 2003 organization in mixed mode. I setup a separate 2008 AD domain/forest with Exchange 2007. I want to connect the two forests/domains together and be able to cross authenticate users and use services running on domain with servers in the other forest. What do I need to do in order to make this work? I assume we setup a two way trust between the two AD forests and then create a routing group in Exchange to connect the two Exchange organizations. But what details am I missing here. We want to be able to move mailboxes back and forth between these two domains and have mail flow between them. In addition we want mail destinted for a moved mailbox in the 2003 domain to route to the new mailbox server running exchange 2007 in the separate forest/domain. I know there has to be more to this setup than what I have mentioned above...any tips?ThanksThanks

You can create corss forest connectors between Exchange 2003 & 2007 orgs for mail flow and you can move mailboxes across the forest with Move-Mailbox cmdlet of Exchange 2007. Configuring Cross-Forest Connectors http://technet.microsoft.com/en-us/library/bb123546.aspx How to Move a Mailbox Across Forests http://technet.microsoft.com/en-us/library/aa997145.aspxAmit Tank | MVP - Exchange | MCITP:EMA MCSA:M | http://ExchangeShare.WordPress.com

hi,addition to Amit ;http://www.msexchange.org/tutorials/Implementing-Exchange-Server-2007-coexistence-Exchange-Server-2003.htmlhttp://msexchangeteam.com/archive/2006/10/09/429135.aspxregards,Mumin CICEK | Exchange - MVP | www.cozumpark.com | www.mumincicek.com

Hi,If we use resource forest topology to deploy exchange. Is there any complications. Company is ready to invest in hardware and infrastructure for different administration purpose.

I have an additional criteria to the answered question above. Does it make any difference if Exchange 2003 is installed on a Small Business Server which controls one of the domains?