Operation unavailable (Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE)) when running through Windows Service?

Question

i am try to hook to outlook application from windows Service but getting an exception Operation unavailable (Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE)) here is my code.

   public void ItemSendEvent()
    {
        try
        {
           if (Process.GetProcessesByName(ApplicationConstants.OUTLOOK_PROCESS_NAME).Count() > 0)
                {
                    // If so, use the GetActiveObject method to obtain the process and cast it to an Application object.
                    outlookApplication = Marshal.GetActiveObject(ApplicationConstants.OUTLOOK_APPLICATION_NAME) as Microsoft.Office.Interop.Outlook.Application;
                    Microsoft.Office.Interop.Outlook.NameSpace nameSpace = outlookApplication.GetNamespace(ApplicationConstants.OUTLOOK_NAME_SPACE);
                    nameSpace.Logon("", "", Missing.Value, Missing.Value);
                    nameSpace = null;
                    outlookApplication.ItemSend += outlookApplication_ItemSend;
                }
                log.Info("Outlook Item Send event registered successfully.");
        }
        catch (System.Exception ex)
        {
            log.Error("Exception occurred while registering Outlook Item Send event. " + ex.Message);
        }
    }

but the same code when i launch it through Windows Form Application its working Fine. i gone through some site's and they were saying that outlook object is not in ROT Table. what will be the solution.

Answer 1

Outlook, or any other Office app, cannot run in a Windows service even if your service is running as an interactive user. Only Extended MAPI (C++ or Delphi only) or an Extended MAPI wrapper like Redemption (I am its author - its RDO family objects) can be used in a service.

In your particular case, it looks like you are trying to trap the Application.ItemSend event. There is absolutely no reason to create a Windows service for that. Create a COM addin - it will be loaded by Outlook and run as long as Outlook itself is running in the same process in the same security context.