Importing and exporting mailboxes to/from PST files is a big deal for a lot of Exchange administrators. So it wasn't surprising when a great cry arose from the masses upon discovery that not only was this feature missing from Exchange 2007 RTM, but Microsoft had also stated they wouldn't support ExMerge running against a 2007 server. Your only option was to perform these tasks using an Outlook client, which is of course tedious and far too slow when dealing with more than, say, 1 mailbox. What was an overburdened Exchange admin to do?
Well if you're like this overburdened Exchange admin you waited for Service Pack 1 and the new cmdlets for handling PST import/export that came with it. Salvation!
But alas, these new cmdlets came with one big caveat that put a huge crimp in the way our company does migrations today. That crimp was the permissions requirements. Straight from the pages of Microsoft documentation:
"The user running the task must be an Exchange Organization Administrator or an Exchange Server Administrator on the server where the mailbox to export or import lives."
Argh! This was a huge pain for my company because the group of people that does ExMerge migrations all day every day were not actually Exchange administrators. They were Exchange view-only admins, and were simply granted Send As and Receive As permissions to the mailboxes they were migrating. I wasn't too keen on granting these people Exchange Server Admin so they could run amok. After all, the old way worked great with ExMerge, but now Microsoft was requiring administrator level permissions to perform the same function.
Or were they? Well, some testing revealed that Microsoft isn't quite correct about the requirements to run their import and export mailbox cmdlets. Administer Information Store, Send As, and Receive As were granted to our migration group on the Exchange 2007 Mailbox server databases, and what do you know... they can run the cmdlets just fine. Crisis averted!
On a final note, ExMerge works just fine against Exchange 2007 as long as the Mailbox server has a Public Folder database, but since it isn't supported our company has decided it's not worth the (infinitessimally small, I'm sure) risk of damaging a database and being told "you're on your own" by the boys in Redmond.