OK, we are in the process of migrating from Exchange 2003 to Exchange 2010. We have moved about 70% of our mailboxes to the 2010 server. My boss has recently posed a request, which I'm pretty sure the answer is no, but I need something to back up telling him no. Once a mailbox has been moved to the new server, is there any way to retain the data from that mailbox on the old server? My assumption is that it is flagged in the EDB file as whitespace, and I can't imagine the headaches it would pose to have a duplicate of that mailbox sitting on the old server. What gives on this, I assume it's gone forever (other than the obvious "move it back").

Yes it's gone. For 2010 SP1 the behavior is changed and it's soft deleted from the source database and can be recovered.James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com

Thank you James, that's what I thought, but now I can substantiate my suspicion.

Good information from James, however, I am curious as to your boss's inquiry, i.e. what did he want to be able to do if the data did remain in the old database? If he was looking for historical access you could use Lucid8's DigiScope http://www.lucid8.com/product/digiscope.asp to open an offline/backup copy of the database pre-move. Once opened you can see all mailboxes and items so that you can browse, search, export to PST, MSG & XML, or if desired recover data direct from the offline database to any production exchange database Troy Werelius www.Lucid8.com Search, Recover, & Extract Mailboxes, Folders, & Email Items from Offline EDB's and Live Exchange Servers with Lucid8's DigiScope