In Exchange 2013 you can do batch mailbox moves, but you might not want to use the defaults to move 20 mailboxes at a time for example, you might want to only allow 2 or 5 mailboxes to move and these values can be changed quite easily.
We can view the defaults by navigating to the following folder:
- C:\Program Files\Microsoft\Exchange Server\V15\Bin ( Replace the drive letter where you have exchange installed.
- Navigate till you find the MsExchangeMailboxReplication.exe.config file.
- Open the file in notepad.
- Using the find feature in notepad you can do a search for “MaxActive” and you will get to the information where we want to be.
Here you can change the last 2 values highlighted to move more mailboxes at once or decrease it to move less users if the server is impacted.
Hope it helps.