Microsoft had introduced “Online Mailbox Move” as part of Exchange 2010 RTM. Though it was named "Online Mailbox Move”, end users had to restart outlook after their mailbox got moved from one database to another. But, it is was definitely an improvement compared with the previous versions of Exchange where the user had to close Outlook while their mailbox got moved.
In 2010 SP1 Beta, the feature has improved much more and it truly does what it says – Online Mailbox Move. Users get prompted to restart Outlook in 2010 RTM mailbox move.
This has changed in 2010 SP1 Beta, in that there is no more user prompts. This is only the case as long as the move is between two 2010 SP1 Beta servers. Let me explain by moving my mailbox from one SP1 Beta to another SP1 Beta database.
My account has the primary mailbox on DB3 and archive on DB2.
I am moving the mailbox to DB7 which is in my second 2010 server.
The move completes successfully and the mailbox properties gets updated.
My outlook was still online, no user prompts whatsoever. I did notice that outlook got disconnected for a second after the mailbox move was completed, but got connected to exchange the next second. For an end user, this shouldn’t be an issue at all. Even if they press the “send” button at the very second the mailbox got disconnected, the emails will be stored in the “Outbox” and will be send the next second when the mailbox gets connected.
I did send an email after the mailbox move from my account to administrator with a subject “Email after mailbox move”. Note that I didn’t close or re-launch outlook.
And my administrator did get the email without any delay!
Certainly a big improvement. You can now move your mailboxes in the background without even letting the end user know, as long as it is between two SP1 Beta servers! The feature should be available in SP1 RTM as well.