Microsoft 365 Alert – Service Degradation – Microsoft Defender XDR – Users aren’t seeing the latest email data in hunting experiences for Microsoft Defender for Office 365 – RESOLVED

Announcements Arpan Das

15/12/2025 14:24:00 AM

NHSmail Reference: INC46706788

Microsoft Reference: DZ1197442

Issue Status: RESOLVED

Issue Description: Users aren’t seeing the latest email data in hunting experiences for Microsoft Defender for Office 365.

Final Update: 16/12/2025 14:26:00 PM – Microsoft have successfully optimized performance parameters on the remaining infrastructure in the United Kingdom, and service telemetry now indicates that impact has been fully resolved.

Scope of impact: Your organization was impacted by this event, and users weren’t seeing the latest email data in hunting experiences for Microsoft Defender for Office 365. This section may have been updated as our investigation continues.

Root cause: A portion of service infrastructure that processes email data for hunting experiences in Microsoft Defender for Office 365 was performing sub-optimally, leading to impact.

Next update by: Microsoft are analyzing performance data and trends on the affected infrastructure to help prevent this problem from happening again.