Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may be unable to access email messages in Outlook Mobile when connecting to Exchange on‑premises – RESOLVED

14/04/2026 8:41:00 AM

NHSmail Reference: INC46797773

Microsoft Reference: EX1278714

Issue Status: RESOLVED

Issue Description: Some users may be unable to access email messages in Outlook Mobile when connecting to Exchange on‑premises.

Final Update: 14/04/2026 8:41:00 AM– The fix to correct the misconfiguration has been deployed and we’ve confirmed through various user testing that this has successfully mitigated this issue and service has been restored. Users need to re-add their account in Outlook Mobile so that the Autodiscover flow for Exchange on-premises connections will once again connect correctly.

Scope of impact: Your organization was affected by this event, and some users attempting to access email messages in Outlook Mobile when connecting to Exchange on‑premises may have been impacted.

Root cause: An authentication component misconfiguration was impacting the Autodiscover flow for Exchange on‑premises connections, which was preventing Outlook Mobile from automatically establishing access for affected users.

Next steps: They will continue to review the component configuration to understand the misconfiguration in an effort to prevent future similar events.