After finding users cannot set AutoReplies ie. out of the Office from Outlook error suggested Exchange Server is not online (but users can send receive emails and can set AutoReplies from OWA)
I decided to run Microsoft Connectivity analyzer - I get the following error
Microsoft Connectivity Analyser
Creating a temporary folder to perform synchronization tests.
Failed to create temporary folder for performing tests.
Additional Details
Exception details:
Message: The request failed. The remote server returned an error: (440) Login Timeout.
Type: Microsoft.Exchange.WebServices.Data.ServiceRequestException
Stack trace:
at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request)
at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ValidateAndEmitRequest(IEwsHttpWebRequest& request)
at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.Execute()
at Microsoft.Exchange.WebServices.Data.ExchangeService.BindToFolder[TFolder](FolderId folderId, PropertySet propertySet)
at Microsoft.Exchange.Tools.ExRca.Tests.GetOrCreateSyncFolderTest.PerformTestReally()
Exception details:
Message: The remote server returned an error: (440) Login Timeout.
Type: System.Net.WebException
Stack trace:
at System.Net.HttpWebRequest.GetResponse()
at Microsoft.Exchange.WebServices.Data.EwsHttpWebRequest.Microsoft.Exchange.WebServices.Data.IEwsHttpWebRequest.GetResponse()
at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request)
Elapsed Time: 595 ms.