We are getting ready to go to Exchange 2007 SP1 next month. We currently have a stand alone BES 4.1.4 MR3 on a 2003 SP2 server in production connecting to a Exchange 2003 SP2 server. I am taking notes as I read this post, but my question is if everything goes well at the server after we move all the mailboxes to a new Exchange 2007 server uninstall esm from 2003, install the esm equivalent from 2007, and set the permissions, what will the clients see on their end? Will we have to enterprise activate all of the users again once the new 2007 Exchange server is in place? Will their email dissappear? I am assuming they won't be able to reply to any of their email that is on their device stamped with the old exchange server as the source? I know email on the Blackberry is just a mirror of what is in Outlook but just checking.

Thanks