Centralized Deployment for Outlook add-ins will now be generally available

Christoph Ratavaara - Though we dont have a whitelist addin feature, you can achieve the same result by the following.

You can disable all outlook addins using My Marketplace role. For more details, please refer to the following links

https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/add-ins-for-outlook/specify-who-can-install-and-manage-add-ins

https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/add-ins-for-outlook/add-ins-for-outlook

You can then use Centralised deployment to deploy the selected (whitelist) addins to the set of users/groups who you want to provide access with. These users will be able to use only the addins you provided and will not be able to install any of the outlook addins from the marketplace. Please try this out and let me know if it works.