Teams to Block Federated Communications with Trial Tenants

Microsoft is moving to block federated communications with trial Microsoft 365 tenants to cut off a potential exploitation route for attackers. The new block goes into force on July 29, 2024, and is controlled by the ExternalAccessWithTrialTenants setting in the tenant federation configuration policy. We’ve been saying for years that tenants should clamp down on federated chat. It seems that Microsoft now agrees.

https://office365itpros.com/2024/06/27/federated-communications-block/