Microsoft Teams: File sharing enabled by default in external (federated) chats

Microsoft Teams will enable file sharing by default in external (federated) chats starting late October 2026, simplifying cross-organization collaboration by removing manual permission steps. Admins can disable this via PowerShell. Files are stored in the sender’s OneDrive with existing security controls applied. We are updating Microsoft Teams file sharing in external (federated) chats by changing the default setting from Disabled to Enabled. Today, admins must explicitly enable file sharing in external chats before users can attach files when collaborating with people outside their organization. This update simplifies cross-organization collaboration by allowing users to attach files directly in external (federated) chats and automatically applying the required permissions to shared files. Together, these changes remove both the tenant configuration step and the manual permission assignment step that can slow cross-organization collaboration. Existing OneDrive, SharePoint, and security controls continue to govern access.  Admins retain full control and can disable file sharing or automatic permission assignment at any time using PowerShell. Rollout schedule Targeted Release: Beginning in late October 2026 and expected to complete by late November 2026 General Availability (Worldwide, GCC, GCC High, DoD): Beginning in late October 2026 and expected to complete by late November 2026 Impact on your organization Who is affected Organizations using Microsoft Teams external access (federation) Organizations that previously disabled file sharing in external chats Users participating in external 1:1 chats, external group chats, and meeting chats Platforms and services Microsoft Teams External (federated) 1:1 chats External (federated) group chats Meeting chats Teams desktop app Teams web app What will happen File sharing in external chats will be enabled by default for all Microsoft 365 tenants. This change applies even if your organization previously configured the setting as Disabled. Organizations that want file sharing in external chats to remain disabled must reapply the disabled setting after rollout. Users will see the Attach file (paperclip) option in external (federated) chats. Previously, users could only paste existing links in external chats. Users can share files by attaching a file or dragging and dropping a file into the compose box. Teams will automatically grant the required permissions to participants in the […]

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