Error: [The server cannot service this request right now] error from the Sent Items Update service

Relevant Product: Signature Manager Exchange Edition

Scenario

When using Exclaimer Signature Manager Exchange Edition's Sent Items Update service, you may see the following error in the Event Log:

The sent item noted in the event may take a while to update (over 15 minutes), or it may not be updated at all.

Reason

This error is most likely caused by the Exchange Web Services (EWS) throttling, particularly on busy servers.

Resolution

To resolve this issue, remove EWS throttling from the Sent Items Update service account (ExclaimerSIUS, by default).

To do this:

1. Open the Exchange Management Shell.
   
   
2. Create a new throttling policy. For example: 'ExclaimerSIUSPolicy', using the following command:
   
   New-ThrottlingPolicy ExclaimerSIUSPolicy 
   
3. Run one of the following commands (depending on the Exchange version) to change the new throttling policy and set the EWS connections for 'ExclaimerSIUSPolicy' to 'Null/Unlimited':
   
   For Exchange 2010:
   
   Set-ThrottlingPolicy ExclaimerSIUSPolicy -RCAMaxConcurrency $null -RCAPercentTimeInAD $null -RCAPercentTimeInCAS $null -RCAPercentTimeInMailboxRPC $null -EWSMaxConcurrency $null -EWSPercentTimeInAD $null -EWSPercentTimeInCAS $null -EWSPercentTimeInMailboxRPC $null -EWSMaxSubscriptions $null -EWSFastSearchTimeoutInSeconds $null -EWSFindCountLimit $null -CPAMaxConcurrency $null -CPAPercentTimeInCAS $null -CPAPercentTimeInMailboxRPC $null -CPUStartPercent $null
   
   -or-
   For Exchange 2013 and above:
   
   
   Set-ThrottlingPolicy ExclaimerSIUSPolicy -RCAMaxConcurrency Unlimited -EWSMaxConcurrency Unlimited -EWSMaxSubscriptions Unlimited -CPAMaxConcurrency Unlimited -EwsCutoffBalance Unlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited
4. Apply the new policy to the Exclaimer Sent Items Update service account:
   
   
   Set-Mailbox "ExclaimerSIUS" -ThrottlingPolicy ExclaimerSIUSPolicy
5. Restart the Exclaimer Sent Items Update service (this will not affect the mail flow).

If the error persists

1. Open a command prompt as an Administrator.
   
   
2. Run IISRESET. Please note that this will briefly impact some Exchange services.
   
   
3. Restart the Exclaimer Sent Items Update service.
   
   
4. If you continue to see the same error, please raise a support ticket.