Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal

Vendor: Microsoft
Product: Microsoft Teams, Microsoft Defender for Office 365
Type: Security
Announcement date: 2025-12-12
Effective date: 2026-01-28
Impact: Affected

In brief

What the source says

Security admins with Defender for Office 365 Plan 1 and above can block external users from sending messages, calls, meetings invitation over Microsoft Teams via the Tenant Allow Block List in Microsoft Defender portal. Updated January 28, 2026: We are pausing rollout at this time as we address an ongoing issue. We apologize for any inconvenience. GA date: February CY2026 Launched General Availability Worldwide (Standard Multi-Tenant) Microsoft Defender for Office 365 Microsoft Teams Web

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Reading for a salesperson

Who is affected: The audience described by the Microsoft update is represented by: Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal Security admins with Defender for Office 365 Plan 1 and above can block external users from sending messages, calls, meetings invitation over Microsoft Teams via the Tenant Allow Block List in Microsoft Defender portal. Updated January 28, 2026: We are pausing rollout at this time as we address an ongoing issue. We apologize for any inconvenience. GA date: February CY2026 Launched General A

Why it matters: The change matters because the official source describes: Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal Security admins with Defender for Office 365 Plan 1 and above can block external users from sending messages, calls, meetings invitation over Microsoft Teams via the Tenant Allow Block List in Microsoft Defender portal. Updated January 28, 2026: We are pausing rollout at this time as we address an ongoing issue. We apologize for any inconvenience. GA date: February CY2026 Launched General A

Urgency: Immediate

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Raw capture
2026-08-29T09:22:49.319599+00:00
Event
Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal Security admins with Defender for Office 365 Plan 1 and above can block external users from sending messages, calls, meetings invitation over Microsoft Teams via the Tenant Allow Block List in Microsoft Defender portal. Updated January 28, 2026: We are pausing rollout at this time as we address an ongoing issue. We apologize for any inconvenience. GA date: February CY2026 Launched General Availability Worldwide (Standard Multi-Tenant) Microsoft Defender for Office 365 Microsoft Teams Web
source
Product Microsoft Teams
Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal Security admins with Defender for Office 365 Plan 1 and above can block external users from sending messages, calls, meetings invitation over Microsoft Teams via the Tenant Allow Block List in Microsoft Defender portal. Updated January 28, 2026: We are pausing rollout at this time as we address an ongoing issue. We apologize for any inconvenience. GA date: February CY2026 Launched General Availability Worldwide (Standard Multi-Tenant) Microsoft Defender for Office 365 Microsoft Teams Web
source
Product Microsoft Defender for Office 365
Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal Security admins with Defender for Office 365 Plan 1 and above can block external users from sending messages, calls, meetings invitation over Microsoft Teams via the Tenant Allow Block List in Microsoft Defender portal. Updated January 28, 2026: We are pausing rollout at this time as we address an ongoing issue. We apologize for any inconvenience. GA date: February CY2026 Launched General Availability Worldwide (Standard Multi-Tenant) Microsoft Defender for Office 365 Microsoft Teams Web
source
Insight a salesperson
Microsoft Defender for Office 365: Admins can block external users in Microsoft Teams from Defender Portal Security admins with Defender for Office 365 Plan 1 and above can block external users from sending messages, calls, meetings invitation over Microsoft Teams via the Tenant Allow Block List in Microsoft Defender portal. Updated January 28, 2026: We are pausing rollout at this time as we address an ongoing issue. We apologize for any inconvenience. GA date: February CY2026 Launched General Availability Worldwide (Standard Multi-Tenant) Microsoft Defender for Office 365 Microsoft Teams Web
source

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