When you click View Details, you see error details like the following:
ActivityId: <GUID>
>Error : System.Net.WebException: The request failed with HTTP status 404: Not Found.
at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Services.Protocols.SoapHttpClientProtocol.EndInvoke(IAsyncResult asyncResult)
at Microsoft.Crm.Asynchronous.EmailConnector.ExchangeServiceBinding.EndFindItem(IAsyncResult asyncResult)
at Microsoft.Crm.Asynchronous.EmailConnector.FindItemsStep.EndCall()
at Microsoft.Crm.Asynchronous.EmailConnector.ExchangeIncomingEmailProviderStep.EndOperation()
ActivityId: <GUID>
>Error : System.Net.WebException: The request failed with HTTP status 404: Not Found.
at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Services.Protocols.SoapHttpClientProtocol.EndInvoke(IAsyncResult asyncResult)
at Microsoft.Crm.Asynchronous.EmailConnector.ExchangeServiceBinding.EndCreateItem(IAsyncResult asyncResult)
at Microsoft.Crm.Asynchronous.EmailConnector.ExchangeOutgoingEmailProvider.EndCreateItem()
T:593
ActivityId: <GUID>
>Exception : Unhandled Exception: Microsoft.Exchange.WebServices.Data.ServiceRequestException: The request failed. The remote server returned an error: (404) Not Found. at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.EndGetEwsHttpWebResponse(IEwsHttpWebRequest request, IAsyncResult asyncResult) at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.EndInternalExecute(IAsyncResult asyncResult) at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.EndExecute(IAsyncResult asyncResult) at Microsoft.Exchange.WebServices.Data.ExchangeService.EndSyncFolderHierarchy(IAsyncResult asyncResult) at Microsoft.Crm.Asynchronous.EmailConnector.MonitoredExchangeService.EndSyncFolderHierarchy(IAsyncResult asyncResult) at Microsoft.Crm.Asynchronous.EmailConnector.ExchangeSyncSteps.ExchangeSyncAsyncRemoteStep`2.AfterCall() at Microsoft.Crm.Asynchronous.EmailConnector.ExchangeSyncSteps.ExchangeSyncAsyncRemoteStep`2.E...