How to resolve 'The server cannot service this request right now' errors from the Sent Items Update service

Scenario:

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

15:53:25.295: Information: Update failed. There was an error writing message to the Exchange Store.  15:53:25.295: Warning: There was an error updating Sent Item for the sender example@emailaddress.com  The server cannot service this request right now. Try again later.

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

Reason:

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

Solution:

To resolve this issue, you should remove EWS throttling from the Sent Items Update service account (ExclaimerSIUS, by default). To do this, follow the steps below:

1. Open the Exchange Management Shell.
2. Create a new throttling policy (for example: “Unlimited", using the following command:




New-ThrottlingPolicy Unlimited    




3. Run one of the following commands (depending on Exchange version) to change the new throttling policy, setting the EWS connections for “Unlimited” to “Null/Unlimited”:




For Exchange 2010:




Set-ThrottlingPolicy Unlimited -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 MigrationWizPolicy -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 Unlimited    

5. Restart the Exclaimer Sent Items Update service (this will not affect 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.

If you continue to see the same error, please raise a support ticket.