Clean MailboxDatabase Command no longer Valid on #Exchange 2013 Clean-MailboxDatabase Command has  been decommissioned for Exchange 2013 and replaced with Update-StoreMailboxState http://technet.microsoft.com/en-us/library/jj860462(v=exchg.150).aspx Update-StoreMailboxState require the GUID of a mailbox to execute so it usually easier to run in combination with Get-MailboxStatistics like the example below Get-MailboxStatistics -Database MDB02 | ForEach { Update-StoreMailboxState -Database $_.Database -Identity $_.MailboxGuid…