492985 – Microsoft Teams: Microsoft Teams integration with Microsoft Defender for Office Tenant Allow block list for domains.

Product:

Defender, Defender for Office 365, Teams

Platform:

Web, World tenant

Status:

In development

Change type:

Links:

Details:

Security admins can use the Tenant Allow/Block List feature in the Microsoft Defender portal to block domains for Microsoft Teams.

Change Category:
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Scope:
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Release Phase:
General Availability

Created:
2025-05-15

updated:
2025-06-17

Docu to Check

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MS workload name

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summary for non-techies**

Microsoft Defender for Office 365 integrates with Microsoft Teams to enhance security by using the Tenant Allow/Block List feature, enabling admins to control which external domains can interact with the Teams environment, similar to a security team managing access to a physical office building.

Direct effects for Operations**

Domain Blocking Impact
Blocking domains may prevent users from accessing necessary external resources, leading to disruptions in communication and collaboration.
   - roles: Security Admin, End User
   - references: https://techcommunity.microsoft.com/t5/microsoft-defender-for-office/announcing-the-tenant-allow-block-list-for-microsoft-teams/ba-p/3651230

User Experience Degradation
Users may experience frustration and decreased productivity if legitimate domains are mistakenly blocked, resulting in a lack of access to important tools or information.
   - roles: End User, IT Support
   - references: https://www.microsoft.com/en-us/microsoft-365/blog/2021/09/22/introducing-the-tenant-allow-block-list-for-microsoft-teams/

Increased Support Tickets
The implementation of domain blocking without proper preparation may lead to an increase in support requests from users facing access issues, straining IT resources.
   - roles: IT Support, Help Desk
   - references: https://www.forbes.com/sites/bernardmarr/2021/09/23/microsoft-teams-new-features-what-you-need-to-know/?sh=4c1b1c1e7c3b

Configutation Options**

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Opportunities**

Enhanced Security Management
Integrating Microsoft Teams with the Tenant Allow/Block List in Microsoft Defender for Office allows security admins to better manage domain access, reducing the risk of phishing and other malicious activities targeting Teams users. This proactive approach can lead to a safer collaboration environment.
   - next-steps: Conduct a security assessment to identify high-risk domains and establish a protocol for regularly updating the allow/block list based on emerging threats.
   - roles: Security Admins, IT Managers, Compliance Officers
   - references: https://techcommunity.microsoft.com/t5/microsoft-defender-for-office-365/tenant-allow-block-list-in-microsoft-defender-for-office-365/ba-p/3053501, https://www.microsoft.com/en-us/microsoft-365/blog/2021/05/11/whats-new-in-microsoft-defender-for-office-365-may-2021/

Improved User Experience
By utilizing the Tenant Allow/Block List, organizations can streamline user experience in Teams by preventing unwanted spam and malicious links, allowing users to focus on productive collaboration without interruptions.
   - next-steps: Gather user feedback on current experiences with Teams and identify common issues related to domain access. Use this data to inform the implementation of the allow/block list.
   - roles: End Users, Productivity Managers, User Experience Designers
   - references: https://www.microsoft.com/en-us/microsoft-365/blog/2021/05/11/whats-new-in-microsoft-teams-may-2021/, https://www.techtarget.com/search/query?q=Microsoft+Teams+user+experience

Centralized Policy Management
The integration allows for centralized management of domain policies across Teams and other Microsoft 365 services, simplifying administrative tasks and ensuring consistent security policies are enforced across the organization.
   - next-steps: Develop a policy management framework that incorporates the Tenant Allow/Block List and train IT staff on its usage to ensure effective policy enforcement.
   - roles: IT Administrators, Policy Managers, Compliance Officers
   - references: https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/tenant-allow-block-list?view=o365-worldwide, https://www.microsoft.com/en-us/security/business/solutions/microsoft-defender

Potentional Risks**

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IT Security**

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explanation for non-techies**

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