Microsoft Teams will let admins block custom file extensions

Microsoft is expanding admin settings for Weaponizable File Protection in Teams: starting November 2026, admins can define their own list of blocked file extensions instead of Microsoft's fixed set. The feature will be available on Android, iOS, macOS, Windows, and the web.

• Custom blocked extension list arrives November 2026
• Currently admins cannot change the file type list
• From December, external users can be blocked via Defender
• Feature covers Android, iOS, macOS, Windows, and web