Microsoft 365 Alert – Service Degradation – Microsoft Teams – Some users’ legitimate email messages may be marked as phishing and quarantined in Exchange Online – RESOLVED

09/02/2026 08:30:00 AM

NHSmail Reference: INC46744068

Microsoft Reference: EX1227432

Issue Status: RESOLVED

Issue Description: Users’ legitimate email messages may be marked as phishing and quarantined in Exchange Online.

Final Update: 13/02/2026 09:01:00 AM – Microsoft has validated the successful release of the small portion of remaining messages and confirmed the impact associated with this incident is now resolved.

Scope of impact: Some users attempting to send or receive Exchange Online email messages may be impacted.

Preliminary root cause: An updated URL rule intending to identify more sophisticated spam and phishing email messages is incorrectly quarantining legitimate email messages in Exchange Online, resulting in impact.

Next Steps: Microsoft are reviewing their ongoing URL rule implementation processes to find ways to reduce similar false positive detections in the future while continuing to adapt and respond to evolving spam and phishing techniques.