Previously, users needed to manually update file permissions for external collaborators. Teams now handles this automatically.
With this update, file attachments and Loop components are enabled by default in external 1:1, group, and meeting chats.
→ External participants can instantly access shared Files and Loop components without manual permission updates.
→ Guest users can upload files directly from their home tenant’s OneDrive or SharePoint.
→ Shared files show an External tag for visibility and always open on the web.
→ Recipients access shared content as B2B guests within the resource tenant.
If not already added, they’ll need to give consent and may be required to complete MFA based on your organization’s B2B policy.
Rollout Timeline
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Targeted Release: Late October – Mid November 2025
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General Availability: Mid January 2026
Admins who prefer to retain manual sharing control can disable automatic file provisioning by setting the AutoShareFilesInExternalChats attribute in TeamsMessagingPolicy to Disabled.