This will ensure that your users continue to have support for critical add-ins in the new Outlook version. You can check installed COM/VSTO add-ins by following the instructions here.

Start migrating any COM/VSTO add-ins that your organization uses, to web add-ins.

To have your Add-in(s) working in the new Outlook Microsoft recommends you to:

It continues to be an area of constant investment at Microsoft, and Microsoft is strengthening the platform even further so that most COM/VSTO add-in capabilities are supported. The web add-in platform provides a robust experience and an easy way to deploy add-ins across Outlook endpoints. During the transition, both the new Outlook and classic Outlook will get the latest features for Outlook web add-ins. Please note that COM/VSTO add-ins will not be supported in the new Outlook for Windows but will continue to work in classic Outlook for Windows.

In line with this, Microsoft is committed to providing a unified and reliable experience for apps built on top of Outlook, and hence, only web add-ins will be supported in this new version of Outlook for Windows. With the new Outlook for Windows, our goal is to bring rapid access to new features through a shared codebase and ensure platform consistency and robustness. One of the top feedback items Microsoft hears today is that Outlook works differently on different platforms, making it hard for tenants to manage, and for users to seamlessly use it across endpoints. MC528299 – Microsoft recently announced the expansion of new Outlook for Windows to Current Channel users in April 2023, with the goal of providing a unified, modern and robust Outlook experience across desktop and web.

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