Some users may experience issues when accessing their Exchange Online mailbox via one or more connection methods

Title: Some users may experience issues when accessing their Exchange Online mailbox via one or more connection methods User impact: Users may experience issues when accessing their Exchange Online mailbox via one or more connection method. More info: Impacted connection methods included, but weren't limited to: - Outlook on the web - Exchange ActiveSync (EAS) - Messaging API (MAPI) Final status: We've identified that a section of mailbox database infrastructure, responsible for processing requests to access Exchange Online mailboxes using any connection method, was performing below acceptable performance thresholds. While we were in the process of troubleshooting the impact, system monitoring indicated that the service had returned to normal health. We've confirmed that the impact is mitigated and service is fully restored. Scope of impact: Impact was specific to some users in the United Kingdom attempting to access their mailbox via one or more connection methods. Start time: Thursday, May 14, 2026, at 10:30 AM UTC End time: Thursday, May 14, 2026, at 11:40 AM UTC Root cause: A section of mailbox database infrastructure, responsible for processing requests to access Exchange Online mailboxes using any connection method, was performing below acceptable performance thresholds. Next steps: We're analyzing performance data and trends on the affected infrastructure to help prevent this problem from happening again. This is the final update for the event.

Title: Some users may experience issues when accessing their Exchange Online mailbox via one or more connection methods User impact: Users may experience issues when accessing their Exchange Online mailbox via one or more connection method. More info: Impacted connection methods include, but may not be limited to: - Outlook on the web - Exchange ActiveSync (EAS) - Messaging API (MAPI) Current status: We’re reviewing service telemetry data to help identify the root cause and next steps required to mitigate impact. Scope of impact: Impact is specific to some users in the United Kingdom attempting to access their mailbox via one or more connection methods. Next update by: Thursday, May 14, 2026, at 2:00 PM 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.