In Exchange 2010 and 2013 we can Exclude Databases from Mailbox move, This is very handy If you want to load balance the Databases with an even number of mailboxes.
When moving mailboxes we don’t have to specify mailbox database so If we have a DAG we can simply exclude all non DAG mailbox Databases and Exchange will only move the mailboxes to the DAG.
To Exclude Mailbox Database Open EMS and run the following cmdlet:
Set-MailboxDatabase -Identity “Mailbox Database 0989143367” -IsExcludedFromProvisioning $true
To Not Exclude run this cmdlet:
Set-MailboxDatabase -Identity “Mailbox Database 0933135909” -IsExcludedFromProvisioning $false