Preventing Users from Installing and Managing Outlook Add-ins

Learn how to revoke the ability for your end-users to install Outlook (Office) Add-ins for greater control and security.

As a global administrator, navigate to the new Exchange admin center interface here: https://admin.exchange.microsoft.com/.
Expand the Roles section in the sidebar navigation and select User roles.
Click on Default Role Assignment Policy and then Manage permissions to open the edit window.
Deselect My Custom Apps, My MarketPlace Apps, and My ReadWriteMailbox Apps.
Click Save changes to prevent end-users from installing and managing Outlook Add-ins.

As a global administrator, navigate to User Roles in the legacy (not new) Exchange admin center interface here: https://outlook.office365.com/ecp/.
Select Permissions, then User Roles.
Click the edit icon () to open the Role Assignment Policy editing interface in a new window.
Scroll down to the Other roles section and deselect the My Custom Apps, My MarketPlace Apps, and My ReadWriteMailbox Apps checkboxes.
Click Save to prevent end-users from installing and managing Outlook Add-ins.