With Microsoft Teams, there is an important difference configuring OPEN FEDERATION.
While in Skype for Business, it was a simple Option:
Off, Open with blocked Domains or Blocked with Allowed Domaind
In Teams, it is different.
Team Open Federation is activ by default !
Soon you are adding a "Allowed Domain", the Open Federation is revoked.
Only Federation with users in the allowed Domain list is possible !
Remove all Allowed Domains in Teams Admin Portal
Different with Blocked Domains, here the Open Federation will be kept, but blocked Domains are expluded from Federation!
In Teams Admin Portal, you will find the Statement About Federation.
External access lets your Teams and Skype for Business users communicate with other users that are outside of your organization. By default, your organization can communicate with all external domains. If you add blocked domains, all other domains will be allowed but if you add allowed domains, all other d…