Microsoft Teams will let admins block custom file extensions

Microsoft Teams will soon let administrators tweak the list of file extensions commonly associated with malware and security threats to meet their company's security requirements.

This will come as an update to Weaponizable File Protection, a built-in Teams messaging safety feature that scans conversations and blocks chat or channel messages with dangerous, high-risk file attachments.

As detailed in a new Microsoft 365 roadmap entry, the feature is currently in development and will start rolling out in November 2026.

"Microsoft Teams is expanding admin controls for Weaponizable File Protection. Administrators will be able to customize which file types are blocked in Teams to align with their organization's security requirements or continue using the Microsoft-recommended default list," Microsoft says.