I need to migrate a load of users from an OLD forest running Exchange 2007 to a new one running Exchange 2010. 2007 is at SP1 and evidence suggests that this won't work. Does anyone know if this is correct or if it just doesn't work online etc..? Is the only option to upgrade to SP2?

David, Yes, you are correct, you must upgrade Exchange 2007 in your source forest to at least SP2 to be compatible with Exchange 2010 (this includes cross-forest moves.) If you will be migrating Public Folder content you should take care to install an Exchange 2007 server into the forest BEFORE installing Exchange 2010. IORepl will allow you to migrate public folder content cross-forest but you have to have Exchange 2007 servers at the endpoints. This article has the best content for what you're looking for: http://blogs.technet.com/b/exchange/archive/2010/08/10/3410619.aspx Hope this helps, Wes Microsoft Messaging PFE

Hi ukDavidC, Yes, you cannot move mailboxes from Exchange 2007 SP1 to Exchange 210. You can refer to this: Supported Scenarios for Moving Mailboxes The following table lists the supported scenarios for moving Exchange mailboxes and includes links to related topics. Supported scenarios for moving mailboxes Moving from Moving to Supported Online move supported Related topic Exchange 2010 Exchange 2010 Yes Yes Managing Move Requests Exchange 2007 SP2 Exchange 2010 Yes Yes Move Mailboxes from Exchange 2007 Servers to Exchange 2010 Servers Exchange 2007 SP1 Exchange 2010 No No Move Mailboxes from Exchange 2007 Servers to Exchange 2010 Servers Exchange 2003 SP2 Exchange 2010 Yes No Move Mailboxes from Exchange 2003 Servers to Exchange 2010 Servers Online mailbox moves are supported between Exchange 2010 databases and between Exchange 2007 SP2 and Exchange 2010 databases. You can perform online mailbox moves across forests or in the same forest. Related document for you: Understanding Move Requests http://technet.microsoft.com/en-us/library/dd298174.aspx When you move mailboxes cross-forest from Exchange 2007 to Exchange 2010, here is a related document for you: Prepare Mailboxes for Cross-Forest Move Requests http://technet.microsoft.com/en-us/library/dd298174.aspx Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.