On February 8th 2021, Microsoft will enable Guest Access for Microsoft Teams by default for all customers unless they have explicitly turned it off.
What this means is that post February 8th your users may be able to invite others to your Microsoft Teams instance, or be invited to other organizations’ Teams instance as a guest.
Lets say your user Joe, gets invited to collaborate in Contoso’s Microsoft Teams instance. They’ll be able to joint the Contoso Tennant and collaborate in that Teams instance. The issue is that all the content they create there – Posts, Uploads etc are in no way discoverable or manageable by IT and represent massive data leakage potential.
For the majority of customers this may have some very serious discoverability ramifications. Click here to view a demo of the issue in action. The ability of IT to control users joining/signing up in other organizations is not simple to control. Your org may have to deploy new proxy servers to try filter traffic destined for other tenants and IT has no control over those remote accounts. (Youre unable to delete a guest account created on behalf of your user in someone else’s Tennant.)
Microsoft Teams Guest access comes with a host of other user experience issues from broken search to cloud phone system service disappearing from teams (You are unable to place calls when youre “guesting” since you’re no longer logged into your home system which hosts your DLP and your phone system)
A wide swath of users and admins are about to wake up to a lot of complexity.
Do your homework.
Jeremy Laurenson 