Mastering Office 365 Administration

Administering Office 365 Groups via Office 365 Groups settings

To get to the part of the admin center where the Office 365 Groups controls are, go to Office 365 Admin Center | Settings | Services & add-ins. Scroll down the page and click on Office 365 Groups, as shown in the following screenshot:

You must be a global admin to manage these settings.

Once you click on the Office 365 Groups service, you will see the options available for external users, as shown in the following screenshot:

If you turn on Let group members outside the organization ...