New Outlook: Microsoft will definitely not support COM add-ins

[German]Hope dies last, but now it's finally dead. Microsoft has just clarified in a blog post that the new Outlook app, which will eventually replace the classic Outlook, will not support COM. I touched on this topic here on the blog just a short while ago. Here's a quick update on what's going on.


The new Outlook?

Microsoft e available for Windows as the "new Outlook app" starting in late September 2023. This app is available in the Microsoft Store (for consumers through their personal Microsoft account), and is intended, Microsoft wrote, to replace the previous Windows Mail and Calendar apps. I had reported on this switch in July in the post Microsoft 365: First Windows Mail and Calendar users will be migrated to the new Outlook at the end of August 2023.

It is a free app for Windows users that allows various email accounts and calendars to be included so that they can be managed under the new interface. The app with the new Outlook is said to be pre-installed on devices sold with Windows 11, version 23H2, as well as machines upgraded to Windows 11, version 23H2.

All this would not attract anyone behind the stove, because there is still the classic Outlook as part of many Microsoft Office packages and Office 365, which is used in corporate environments. And the above outline was also my state of affairs for a long time, until a blog reader pointed me to the article The New Outlook and Access/VBA by Karl Donaubauer.

Donaubauer points out that the new Outlook app comes with a serious problem. Microsoft has been a bit fuzzy with its public information about the new Outlook app so far, he says. Donaubauer sees Microsoft's references to replacing the less important Windows Mail and Calendar as misleading for many users, since the reference to classic Outlook in Windows is obscured.

Because on September 12, 2023, Microsoft published a video with a presentation of the new app. Donaubauer noticed that the video makes it clear that all current Outlook variants (Windows, OWA, Mac, Android, iOS) will be unified on a common code base and interface. Cross-platform these days means web-based and Javascript-speaking. And this means that classic Outlook will probably die in the next years and will be replaced by the new Outlook app.


In my German blog post Neue Outlook-App als Problem: Der Ansatz schneidet alle COM-/VBA-Lösungen ab, I had then also pointed out the implication that with the new Outlook app the support for the COM object model and for VBA would be dropped.

Any solutions in enterprise environments that rely on the COM interface or VBA will no longer work in the new Outlook app and are unlikely to be portable. There were mixed reactions in the comments to my post. While some people welcomed the fact that "old braids would finally be cut", other administrators listed the problem that many specialist applications would then no longer work as a problem. VBA, I heard, has been discontinued for years, so it will die. So far, the hope was that Microsoft would at least somehow save COM as an interface in the new Outlook app.

New Outlook app don't support COM

As of October 18, 2023, Microsoft has published the Techcommunity post Add-ins in the new Outlook for Windows (Martin Geuß had picked it up here), which clarifies some things. The post states:

  • In the new Outlook for Windows, so-called web add-ins are to be fully supported, and without requiring any additional work from partners.
  • In contrast, COM-Add-ins (which, however, still work in classic Outlook for Windows) are definitely not supported in the new Outlook for Windows.

Microsoft argues that COM add-ins could manipulate Outlook in many ways. However, this often led to instability and crashes in Outlook. Web add-ins, on the other hand, offer a sandbox environment in which add-ins can work. Web add-ins also have controls that ensure Outlook is more stable and robust, according to Microsoft.

Microsoft lists the advantages of web add-ins for the new Outlook in its article and states that its own COM add-ins will be replaced by web add-ins or their functions implemented elsewhere. These web add-ins are also supposed to work in classic Outlook, so nothing much changes there – there could be a "smooth transition" from COM add-ins to web add-ins there. The blog post also mentions that third party vendors have already changed their add-ins accordingly and there are hints how the change works for developers.

In my eyes, however, it will be exciting if classic Outlook dies in the medium term, but COM-based solutions in the form of specialist applications are available in the company, for which there are no web add-ins as a replacement. This is likely to cause quite a few headaches for IT managers. Or how do you see it?

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