Example found in a crmex-log file
The error, displayed in the CRM Monitor, also appeared in the log file.
2012-01-16 16:10:42,118 INFO [CTP-uox #6689]  (AssignTo) Processing Opportunities
2012-01-16 16:10:42,275 WARN [CTP-uox #6689]  Service response error: [ErrorServerBusy] The server cannot service this request right now. Try again later.
2012-01-16 16:10:42,275 ERROR [CTP-uox #6689]  Error occurred subscribing to events.
Omni.Connection.Ews.EwsServerException: Unable to connect to server: [ErrorServerBusy] ---> Microsoft.Exchange.WebServices.Data.ServiceResponseException: The server cannot service this request right now. Try again later.
“[ErrorServerBusy]”, an Exchange system error, means that the Exchange server is too busy to handle the requests.
Immediate Corrective Actions
The Riva sync service needs to be stopped for an extended period of time to give the EWS server sufficient time to clear the conditions that triggered the Service response error: [ErrorServerBusy] error:
Leave the sync service or sync policy disabled for a minimum of two hours. Re-enable data sync, and confirm that the error does not occur again. If it does, disable data sync for a four-hour period.
Long-term Corrective Actions for Riva On-Premise
The long-term corrective action is to reduce the number of concurrent web service calls on the EWS service so that EWS throttling is not triggered. This may vary, depending on which Exchange system Riva is connecting to:
Switch to using EWS Impersonation method. This greatly reduces the number of web service calls that Riva makes when syncing users concurrently.
To use EWS Impersonation:
For On-Premise Exchange 2013 and 2010 systems that need to use Delegate Full Access permissions, Exchange administrators can choose to disable EWS throttling for the Riva EWS connection user (Exchange service account for Riva). This option is not available for Exchange On-Premise 2007 or 2003, or for most commercially hosted Exchange service providers.
For Office 365 Exchange Online (Personal / Small Business), Commercially Hosted Exchange Services, and Exchange On-Premise 2007
For those Exchange environments, Riva administrators are limited to making changes in the Riva sync policies, as follows.
To minimize web service calls to Exchange: