Users may be unable to access their mailbox with any Exchange Online connection methods

Title: Users may be unable to access their mailbox with any Exchange Online connection methods User impact: Users may have been unable to access their mailbox with any Exchange Online connection methods. Final status: We've completed our investigation and identified a networking performance issue on the portion of affected mailbox infrastructure. We've confirmed after monitoring the environment that service health availability has been fully recovered by our automated recovery services and impact has been resolved. Scope of impact: Any user in Europe may have been impacted and unable to access their mailbox with any Exchange Online connection method. Start time: Tuesday, August 11, 2026, at 12:58 AM UTC End time: Tuesday, August 11, 2026, at 2:03 AM UTC Root cause: The portion of affected mailbox infrastructure encountered a networking performance issue, which led to impact. Next steps: - To help prevent similar impact in the future, we're further reviewing why the affected portion of mailbox infrastructure encountered a networking performance issue, and how we can improve our remediation automation for a more expedited recovery. This is the final update for the event.

Title: Users may be unable to access their mailbox with any Exchange Online connection methods User impact: Users may be unable to access their mailbox with any Exchange Online connection methods. Current status: We've been alerted by our monitoring systems of impact to the Exchange Online mailbox service. We're investigating the service health telemetry and logs to determine the cause of the drop in service availability. In addition, we're also observing some recovery already, and we're monitoring the environment as it recovers to determine whether any manual intervention is required to ensure the impact is fully resolved. Scope of impact: Any user in Europe may be impacted and unable to access their mailbox with any Exchange Online connection method. This section may be updated as our investigation continues. Next update by: Tuesday, August 11, 2026, at 4:30 AM UTC

Title: Potential issues accessing mailboxes via one or more connection methods User impact: Users may experience errors or failures when accessing their mailbox via one or more Exchange Online connection methods. Current status: We're investigating a potential issue and checking for impact to your organization. We'll provide an update within 60 minutes.