Starting mid-February 2026, admins can block external Microsoft Teams users via the Tenant Allow/Block List in the Microsoft Defender portal, controlling access and deleting existing communications. This applies to Teams and Defender XDR, with audit logging and limits of 4,000 domains and 200 emails blocked.
Day in brief
Deploy Microsoft Defender endpoint security to Windows devices using the Defender deployment tool (preview) leads 7 Defender updates
24 January 2026 recorded 6 updated Microsoft Defender documentation changes and 1 relevant Message Center announcement. The most active areas were Endpoint, Defender XDR.
- Deploy Microsoft Defender endpoint security to Windows devices using the Defender deployment tool (preview)
Endpoint · Architecture and deploymentUpdated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
- Deploy Microsoft Defender endpoint security to Windows devices using the Defender deployment tool (preview)Endpoint · Architecture and deployment
Updated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
- Defender Deployment Tool Windows
Endpoint · Endpoint protectionUpdated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
- Defender Deployment Tool WindowsEndpoint · Endpoint protection
Updated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
- Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal
Defender XDR · GeneralStarting mid-February 2026, admins can block external Microsoft Teams users via the Tenant Allow/Block List in the Microsoft Defender portal, controlling access and deleting existing communications. This applies to Teams and Defender XDR, with audit logging and limits of 4,000 domains and 200 emails blocked.
This period briefing was assembled from the tracked Microsoft Learn and Message Center changes.
7 updates
Microsoft Defender XDR
1 updateMicrosoft Defender for Endpoint
6 updatesUpdated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
Updated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
Updated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
Updated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
Updated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.
Updated Microsoft Defender documentation in defender-endpoint/defender-deployment-tool-windows.md.