Clean-mailboxdatabase and Exchange 2013

Clean-MailboxDatabase command has been decommissioned for Exchange 2013 and replaced with Update-StoreMailboxState

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 $_.MailboxGuid -Confirm:$false }

Use the Update-StoreMailboxState cmdlet to synchronize the mailbox state for a mailbox in the Exchange mailbox store with the state of the corresponding Active Directory user account. This is especially useful when you want to show disconnected mailboxes or reflect a change in mailbox quota settings