In the May 2021 release of Outlook for Mac, only the add-ins from the Microsoft AppSource store will continue to work. Injection-based native plugins such as Webex, Zoom and Vera will be disabled.
With the release of MacOS Mojave and Catalina, Apple blocked most injection-based plugins from running due to security & stability concerns. With this change, Microsoft will also block all injection-based plugins in Outlook for Mac for both Microsoft 365 and Outlook 2019. To continue using services like Zoom and Webex, you'll need to migrate your users to the supported add-ins from the Microsoft Store.
In the past, you could download injection based native plugins in Outlook for Mac. Once this block is in place, you'll no longer be able to use these. For example, if you use Webex to create online meetings in Outlook for Mac, you'll no longer be able to do so with the injection-based native plugin.
Anyone using injection-based plugins in Outlook for Mac for both Microsoft/Office 365 and Outlook 2019 desktop clients.
We will deploy this change in May 2021 release of Outlook for Mac. Once the block is in place, you'll no longer be able to use injection-based plugins in production versions of Outlook for Mac as well as Insider Fast & Slow releases.