Exchange 2010 has a client throttling policy activated by default, which protects the Exchange server from users placing too much load on the Exchange server and causing a drop in performance. The throttling policies are not to be confused with the Exchange back pressure function. Back Pressure works on the Hub Transport role, whereas the throttling policies work on the CAS role. This default throttling policy can be viewed via the Exchange Management Shell:
Get-ThrottlingPolicy | Where-Object {$_.IsDefault -eq $true}
This policy is switched to all mailboxes by default. If you use backup software such as CA ArcServe or Symantec BackUp Exec that performs a document level backup, you should create a separate throttling policy for the user of the backup software. If the throttling policy takes effect for users, this is logged in the event log application with the event ID 2915.
This creates a new throttling policy that can be bound to the user for the backup software:
New-ThrottlingPolicy „BackUpUserRichtlinie“ -RCAMaxConcurrency $null -RCAPercentTimeInMailboxRPC $null -RCAPercentTimeInCAS $null -RCAPercentTimeInAD $null
In the next step, the new policy is then assigned to the user
Set-Mailbox backupuser@frankysweb.local -ThrottlingPolicy „BackUpUserRichtlinie“
Information on the Throttling Policis paramenters can be found in the Technet: