求助Exchange EWS 问题

 
     ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2007_SP1);
      service.Credentials = new NetworkCredential(appName, appPassword, emailDomain);
      service.AutodiscoverUrl(appEmail);      service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, user1Email);      Folder newFolder = new Folder(service);
      newFolder.DisplayName = "TestFolder1";      newFolder.Save(WellKnownFolderName.Inbox);      service.ImpersonatedUserId = new ImpersonatedUserId(ConnectingIdType.SmtpAddress, user2Email);      Folder newFolder2 = new Folder(service);
      newFolder2.DisplayName = "TestFolder1";      newFolder2.Save(WellKnownFolderName.Inbox);   以上代码运行报如下异常：
System.Web.Services.Protocols.SoapException: 由于权限不足，与应用程序连接的服务器无法模拟所请求的用户。
  在 Microsoft.Exchange.Services.RequestSoapHeaderServiceExtension.ProcessSoapHeaders(SoapMessage message, Object responsibleObject)
  在 Microsoft.Exchange.Services.RequestSoapHeaderServiceExtension.AfterDeserializeRequest(SoapMessage message)
  在 Microsoft.Exchange.Services.ServiceExtensionManager.DoAfterDeserializeRequest(SoapMessage message)
  在 Microsoft.Exchange.Services.ServiceExtensionManager.<>c__DisplayClass1.<ProcessMessage>b__0()
  在 Microsoft.Exchange.Diagnostics.ExWatson.<>c__DisplayClass8.<SendReportOnUnhandledException>b__4()
  在 Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(TryDelegate tryDelegate, FilterDelegate filterDelegate, CatchDelegate catchDelegate)
  在 Microsoft.Exchange.Diagnostics.ExWatson.SendReportOnUnhandledException(MethodDelegate methodDelegate, IsExceptionInteresting exceptionInteresting, Boolean terminating)
  在 Microsoft.Exchange.Diagnostics.ExWatson.SendReportOnUnhandledException(MethodDelegate methodDelegate, IsExceptionInteresting exceptionInteresting)
  在 Microsoft.Exchange.Services.Core.ServiceDiagnostics.TraceErrorOnUnhandledException(MethodDelegate methodDelegate)
  在 Microsoft.Exchange.Services.ServiceExtensionManager.ProcessMessage(SoapMessage message)
  在 System.Web.Services.Protocols.SoapMessage.RunExtensions(SoapExtension[] extensions, Boolean throwOnException)
  在 System.Web.Services.Protocols.SoapServerProtocol.CreateServerInstance()
  在 System.Web.Services.Protocols.WebServiceHandler.Invoke()
  在 System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest()
再说明一点代理账户 在 “https:///owa/” 你可以访问的。