Microsoft 365 Alert – Service Degradation – Exchange Online – Some users’ inbound email messages sent from Gmail accounts may be incorrectly marked as spam and quarantined – RESOLVED

01/05/2025 08:30:00 AM

NHSmail Reference: INC46518649

Microsoft Reference: EX1064599

Issue Status: RESOLVED

Issue Description: Some users’ inbound email messages sent from Gmail accounts may be incorrectly marked as spam and quarantined.

More info: While Microsoft are focused on remediation, users and admins may be able to create allow rules to prevent email messages from Gmail senders from going to the junk folder.

Final Update: 02/05/2025 08:30:00 AM –  After a period of monitoring, Microsoft have confirmed through their service health telemetry that the completion of reverting to the previous ML model has successfully remediated impact.

Scope of impact: Some users that are expecting to receive email messages sent from Gmail domains in their Exchange Online inbox may be affected by this issue.

Root cause: Microsoft’s ML processes, which safeguard Exchange Online against risky email messages, is incorrectly identifying legitimate email messages as spam due to their similarity to email messages used in spam attacks, which is resulting in impact.

Next Steps: Microsoft continuing to investigate opportunities to improve our ML detection process to reduce false positive detections and prevent similar future impact.