After spending my weekend on moving mailboxes from a 2003 to a 2007 server, I've finally conquered the upgrade project. You would think the 'Move Mailbox' utility built in to 2007 would work. Well...sort of. It did work for about a third of the mailboxes. All the users with tiny mailboxes, of course. The others would error out with dialog messages that I couldn't find help with.
Gave up on 'Move Mailbox' after giving it a few chances. Went back to good ole ExMerge to extract the the stuck mailboxes data and create PST files. After verifying the mailbox stats between the PST files and old Exchange server, I deleted the mailboxes from the old server. Finally, recreated each user and mail account on the new server and began to import the PST files.
Well, someone decided at M$ to not allow importing mailboxes from 32-bit Exchange to Exchange 2007 64-bit. WTF?! Overcame that roadblock by installing the 32-bit Exchage Management Extensions on an XP machine to get the process going, again.
For some added confusion, whoever created the original accounts misspelled most of the company staff names. So, I had to import each PST file individually, matching the incorrect name to the newly created mailboxes. Probably should have asked the CEO how he spelled his last name, or slyly nabbed a business card ... thanks for the opportunity previous IT guy!
Anyways, it was a fun weekend getting this one finished. I did manage to wash some laundry and take the trash out. I am sure the love and admiration from the users will be worth it.