To obtain an overview of the whitespace within a mailbox database in Exchange 2010, you can use the following command:
Get-MailboxDatabase -Status | Select-Object Server,Name,AvailableNewMailboxSpace
Whit this new option, it’s possible to see when you’ve to perform an offline defragmentation of your Exchange mailbox databases. To perform an defragmentation, it is still necessary to put the databases offline.
