Microsoft 365 Alert – Service Degradation – Microsoft Teams – Users in the United Kingdom may experience errors or failures when accessing their mailboxes in Exchange Online – RESOLVED

27/07/2026 08:59:00 AM

NHS.net Connect Reference: INC46890810

Microsoft Reference: EX1438592

Issue Status: RESOLVED

Issue Description: Users in the United Kingdom may experience errors or failures when accessing their mailboxes in Exchange Online.

Final Update: 27/07/2026 08:59:00 AM – Microsoft has confirmed through service health telemetry that availability has recovered, and that the impact to mailbox access in Exchange Online has been resolved.

Scope of impact: Some users who received incoming calls or messages and who were expecting to receive notifications in the Microsoft Teams desktop client for Windows may have been impacted.

Root cause: This issue may have impacted users in the United Kingdom who attempted to access their mailboxes.

Next steps: Microsoft are continuing to monitor service health telemetry to ensure that the traffic remains balanced in an effort to avoid impact like this in the future.