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

Why it matters: Generally available

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.

Affected: Microsoft Defender for Office 365, Microsoft Teams

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