User impact: Users may have been unable to access email messages in Outlook Mobile when connecting to Exchange on‑premises.

Final status: 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.

Start time: Friday, April 10, 2026, at 5:30 PM UTC

End time: Monday, April 13, 2026, at 4:00 PM UTC

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:
– We’ll continue to review the component configuration to understand the misconfiguration in an effort to prevent future similar events.

This is the final update for the event.