Unable to access Exchange Equipment mailbox with EWS

Question

I have setup an Office365 equipment mailbox, so that I can open it in outlook (using Open->Other User's Mailbox), but I am unable to access the mailbox using the C# EWS api. Code to access the mailbox:

_service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, delegateBox);
 _inbox = Folder.Bind(_service, WellKnownFolderName.Inbox);

The result is the following exception:

Exception in ProcessWebException
Microsoft.Exchange.WebServices.Data.ServiceResponseException: The SMTP address has no mailbox associated with it.
at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ProcessWebException(WebException webException)
at   Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(HttpWebRequest request)
at Microsoft.Exchange.WebServices.Data.SimpleServiceRequestBase.InternalExecute()
at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.Execute()
at Microsoft.Exchange.WebServices.Data.ExchangeService.BindToFolder(FolderId folderId, PropertySet propertySet)
at Microsoft.Exchange.WebServices.Data.ExchangeService.BindToFolder[TFolder](FolderId folderId, PropertySet propertySet)
at Microsoft.Exchange.WebServices.Data.Folder.Bind(ExchangeService service, WellKnownFolderName name)

Answer 1

Check that delegateBox actually corresponds to that user's email . Note that user's email can be VERY different from its "login name + domain".

When testing delegation/impersonation access, I recommend to set up delegated/impersonated account as an additional mailbox in Outlook. It will allow to verify there is an actual access to delegated/impersonated mailbox, and to see the actual email addresses.

Answer 2

Resources accounts are disabled by default to you cannot log in. Maybe this is the case.

Why do you want to impersonate as an equipment?