Using Interop.Outlook with the new Outlook

Question

I am trying to figure out how to work with the new outlook that should be released at the end of 2024 as the default outlook( Link ).

When using the new outlook by switching the toggle button

I am not able to initialize the Interop application: _application = Marshal.GetActiveObject("Outlook.Application") as Microsoft.Office.Interop.Outlook.Application;

I am getting the following error:

System.Runtime.InteropServices.COMException: 'Operation unavailable (Exception from HRESULT: 0x800401E3 (MK_E_UNAVAILABLE))'

Any idea what am I missing? Is it possible I can no longer use this API anymore with the new outlook ? I cannot migrate to web add-ins because I must be able to communicate with outlook from my application.

Answer 1

The new Outlook (Monarch) is a replacement for Windows Mail and Windows Calendar, not desktop Outlook (a part of the Office suite), which is still fully supported.

Monarch indeed has no programmatically accessible API besides Web (JS) addins.

If you don't like the fact that Monarch has no usable API, take up it with Microsoft.