MC264095 – Updated July 01, 2021: Microsoft has updated the content below to provide clarity. Thank you for your feedback.
Microsoft is making some changes to Guest Access in Microsoft Teams settings. Currently, Microsoft Teams prevents guest collaboration in the guest tenant once the Allow Guest Access in Teams setting is set to OFF in the M365 Admin Center.
When this will happen
Microsoft will begin and complete rolling this out in late July.
How this will affect your organization
Current behavior for guests:
When you turn Teams guest access OFF for your organization, guests can’t access Teams. Guests are removed from all teams they previously had access to. However, guests are not removed from the Microsoft 365 groups that are associated with the teams and guests still have access to other Microsoft 365 group resources such as SharePoint. If you turn Teams guest access ON again, guests in Microsoft 365 groups will be re-added to the associated teams and regain access.
Updated Guest User Behavior:
When your turn OFF Teams Guest Access in your tenant, Microsoft Teams will continue to block guests from accessing Teams. However, these guests will not be removed from the teams. Since guests are not removed, they are still visible to users in teams and channels and can be @mentioned. If you turn Teams guest access ON again, guests in teams will regain access. You may choose to remove guests when you turn guest access off, but if you turn it back on again you’ll need to reinvite them.
When guest access is turned OFF, no new guests can be added to Teams (no change to the behavior). This change does not affect guest permissions outside of Teams (such as access to files in SharePoint).
- The updated behavior does not remove any previous guest resources access.
- Guests will not be removed from modern groups and will continue to be able to participate in teams, chats and meetings as well as collaborate on resources in the guest tenant.
- Like with any Microsoft 365 workloads, the guest tenant admin would have to remove the guest from the group.
What you need to do to prepare
Please familiarize yourself with the Guest Access feature and how it differs from other external collaboration mechanisms already available within Microsoft Teams. Additionally, you’ll want to understand how changing the Guest Access settings affect the behavior of current and future guests
Microsoft will provide further documentation reflecting the details of the above in a Message Center post update.