Summary
Microsoft is adding a new MessageContents table to Advanced Hunting within Microsoft Defender XDR to help security teams investigate threats involving Microsoft Teams messages. The rollout begins worldwide in late September 2026 and finishes by mid October 2026. Administrators should review role assignments and ensure that only authorized security analysts receive the necessary permissions to view message snippets and associated metadata.
Administrator impact: Review role assignments and Advanced Hunting permissions to control access to the new message content table.
End user impact: No direct end user impact is expected.
Score rationale: This feature introduces new telemetry and requires administrative review of security permissions for threat hunting.
Advanced hunting overview in Microsoft Defender XDR
Microsoft Defender for Office 365 introduces a new MessageContents table in Advanced Hunting for Teams messages, enabling authorized security analysts to query message snippets and metadata for threat investigations. It rolls out worldwide from late September to mid-October 2026, requiring appropriate permissions for access.
Published: 18 Sept 2026
Expires: 14 Nov 2026
Last updated: 18 Sept 2026
Category: Stay Informed
Tags: Microsoft Defender XDR, Feature update, User impact, Admin impact
Microsoft Message
We’re introducing a new MessageContents table in Advanced Hunting for Microsoft Teams messages. This new table helps security operations teams investigate threats in Teams by providing access to Teams message snippets and associated message metadata during threat investigations.
This capability enhances security investigations by allowing authorized analysts to correlate Teams message activity with other security signals available in Advanced Hunting, helping organizations detect, investigate, and respond to threats more effectively.
Rollout schedule
General Availability (Worldwide): Beginning in late September 2026 and expected to complete by mid-October 2026
Impact on your organization
Who is affected
- Security administrators and security analysts who use Microsoft Defender XDR Advanced Hunting
- Organizations that investigate security incidents involving Microsoft Teams communications
Platforms and services
- Microsoft Defender XDR
- Microsoft Defender for Office 365
- Microsoft Teams
- Advanced Hunting
What will happen
- A new MessageContents table will become available in Advanced Hunting.
- Authorized users will be able to query Teams message snippets and related message metadata.
- Analysts can correlate Teams message information with other Advanced Hunting data sources during investigations.
- The table can contain Teams message content, so access is permission controlled.
- Users must have the required Advanced Hunting and message preview permissions to access and query the table. Users without the required permissions will not have access to the table.
- Users without the required permissions will not have access to the table.
- The table currently supports Teams messages available through the underlying Teams message metadata source, including messages containing URLs and federated messages.
Action required and recommendations
No action is required if your organization does not plan to use this capability.
If you plan to use this feature:
- Review existing role assignments and determine which security administrators and analysts should have access to Teams message content for security investigations.
- Review the required Advanced Hunting and message preview permissions before providing access.
- Consider updating internal security investigation procedures and documentation.
Learn more
Advanced hunting overview in Microsoft Defender XDR – Microsoft Defender XDR | Microsoft Learn
Compliance considerations
Question: Does the change alter how existing customer data is processed, stored, or accessed?
Answer: Authorized users with the required permissions can access Teams message snippets and associated message metadata through the new MessageContents table in Advanced Hunting.