The mailbox move process has been fine tuned in Exchange 2013 with the concept of “Batch Move”.
Similar to Exchange 2010, a single or multiple mailboxes can be moved using EAC. Mailbox move can be initiated from the move mailbox option next to a mailbox or by using the “Migration” tab in the “Recipients” node.
A new option exposed in the EAC is the option to use a CSV file as an input to move the mailboxes.
In 2013, every mailbox move needs a batch name, even if it is to move a single mailbox. There is a new option to specify a “large item limit”.
There is an option to send an email report to an admin account, once the move is completed. This is a nice to have feature. So is the option to prepare the mailbox move and start it later.
In 2013, you can move the primary and archive mailbox to different database at the same time.
Do check out the 2013 way of moving mailboxes