Hi, We have a single 2003 AD with Exchange 2003 installed, about 700 users across 5 sites. We want to upgrade to Exchange 2010. Our domain has a few replication issues and a few weird things happening with the scripts folder. We think it best to build a new 2008 AD with Exchange 2010, as a resource domain with linked accounts, leaving the user accounts in to 2003 AD for now and Follow the steps to create a domain trust.This will be a centralised service rather than local office DCs and Exchange servers. We need the SMTP addresses of external and inbound mail to remain eg user@mycompany.com will require to be the email address of the 2010 mailboxes. we'll do a phased creation of mailboxes in 2010 so the @mycompany.com address will also need to remain for those on Exchange 2003. If this were to happen in the 2003 domain we'd do a coexistence of EX2003 & 2010 and move mailboxes. Can this still be done if in to separate domains, with a domain trust? While I know we could setup a new mail organisation in the 2008 domain its the mail routing part and keeping the SMTP address the same across 2 domains that I'm not sure about. We don't user mobile devices or OWA all clients are in a closed network using Outlook client on the desktop. Thanks for any advice

I believe you are talking about resource forest not the resource domain! Let me know if i understood correctly You have to different forests, Forest A (2003) and Forest B (2010) You want to have the Exchange resources in 2010 and AD users in 2003! You want to use the same email address external and inbound mail to remain eg user@mycompany.com (2003) Is this the scenario?Gulab | MCTS-MCITP Messaging: 2010 | MCTS-MCITP Messaging: 2007 | MCC 2011 | Skype: Gulab.Mallah

Hi, yes this would be correct, a resource forest; the existing forest with a single AD 2003 domain where the user accounts will remain - currently this has Exchange 2003 installed also - and a new forest with a 2008 AD domain with Exchange 2010 were the users will have new mailboxes. Yes, we need to keep the same email inbound/external SMTP address to remain, eg user @mycompany.com. In a phased approach we will give users access to their new Ex2010 mailbox, so their email address must be the same. Those users still with an Ex2003 mailbox will continue as normal and will eventually have a new mailbox.

http://technet.microsoft.com/en-us/library/aa998031.aspx http://technet.microsoft.com/en-us/library/bb123524.aspx These articles should have the answers, its just a game of permissions :) Cheers,Gulab | MCTS-MCITP Messaging: 2010 | MCTS-MCITP Messaging: 2007 | MCC 2011 | Skype: Gulab.Mallah