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

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

Title: Some users may be unable to access email messages in Outlook Mobile when connecting to Exchange on‑premises User impact: Users may be unable to access email messages in Outlook Mobile when connecting to Exchange on‑premises. Current status: We've identified that an authentication component misconfiguration is impacting the Autodiscover flow for Exchange on‑premises connections, which is preventing Outlook Mobile from automatically establishing access for affected users. We're developing a fix to correct misconfiguration and once complete, we'll validate its efficacy before deploying to affected environments. Scope of impact: Your organization is affected by this event, and some users attempting to access email messages in Outlook Mobile when connecting to Exchange on‑premises may be impacted. This information may be updated as our investigation continues. Start time: Friday, April 10, 2026, at 5:30 PM UTC Root cause: An authentication component misconfiguration is impacting the Autodiscover flow for Exchange on‑premises connections, which is preventing Outlook Mobile from automatically establishing access for affected users. Next update by: Monday, April 13, 2026, at 6:00 PM UTC