Microsoft 365 Alert – Service Degradation – Exchange Online – Users may intermittently be unable to access Exchange Online – ONGOING

Announcements Arpan Das

25/05/2026 10:06:00 AM

NHSmail Reference: INC46834589

Microsoft Reference: EX1321282

Issue Status: ONGOING

Issue Description: Users may intermittently be unable to access Exchange Online

Current Update: 25/05/2026 10:08:00 AM – Microsoft has confirmed that impact began shortly after certain authentication components stopped functioning as expected. They are furthering their investigation on the diagnostic data to help determine their path towards remediation to restore the affected authentication components.

Scope of impact: This issue may impact users worldwide that are routed through the impacted infrastructure. This information may be updated as our investigation continues.

Root cause: A portion of the structured query language infrastructure responsible for accessing Exchange Online isn’t performing as efficiently as expected, resulting in impact.

Next update by: Monday, May 25, 2026, at 8:30 AM UTC