Dear colleagues,

Microsoft Teams is introducing a new protection feature that blocks messages containing weaponizable file types—such as executables—in chats and channels. This helps reduce the risk of malware and file-based attacks by preventing unsafe content from being shared. This message applies to Teams for Windows desktop, Teams for Mac desktop, Teams for the web, and Teams for iOS/Android.

Teams will block messages containing weaponizable file types (e.g., executables) in chats and channels to reduce malware risks. This feature starts is in general availability in November 2025 (on by default).

Once enabled, Teams will automatically block messages that include weaponizable file types. This applies to both internal and external conversations.

• • Recipients will see a notification that a message was blocked but cannot access the content.
  • Senders will receive a notification and can edit and resend the message without the unsafe file.

Kind regards,  

Enterprise Applications & Solutions Integration (EASI)

Information Technology Services , University of Toronto