EX1253275: Exchange Online Service Health Incident (Service Restored)

[365 Service Alert]

Some users may have experienced issues when accessing their Exchange Online mailbox via one or more connection method .                                                                                                                                                                                    

Some users may have experienced issues when accessing their Exchange Online mailbox via one or more connection method ID: EX1253275 Issue type: Incident Status Service Restored Impacted services Exchange Online Details Title: Some users may have experienced issues when accessing their Exchange Online mailbox via one or more connection method User impact: Users may have experienced errors when accessing their mailbox via multiple Exchange Online connection methods. More info: Users may have experienced errors or failures when attempting to access their mailbox. Impacted connection methods included, but were not limited to: - Outlook on the web - Outlook desktop - Exchange ActiveSync - Other Exchange Online connection protocols Final status: We've confirmed that service has remained healthy for an extended period of time. Our monitoring indicates the issue is no longer occurring for the affected users. Scope of impact: Impact was specific to some users attempting to access their mailbox via any of the connection methods detailed above. Start time: Monday, March 16, 2026, at 9:30 AM UTC End time: Monday, March 16, 2026, at 1:30 PM UTC Preliminary root cause: An underlying issue involving the supporting network infrastructure resulted in a service availability degradation across the Exchange Online connection methods. We're continuing to investigate to determine the full root cause and will provide more information within the Post-Incident Report. Next steps: - We're continuing to examine the underlying circumstances that led to this behavior to understand the root cause. We'll provide a preliminary Post-Incident Report within two business days and a final Post-Incident Report within five business days. Is this message helpful? Did you find this email helpful? Yes No To customize what’s included in this email, who gets it, or to unsubscribe, set your Service health preferences. If you are receiving this email because your Admin added you as a recipient, please contact your Admin to unsubscribe. Privacy Statement Microsoft Corporation, One Microsoft Way, ​Redmond, WA 98052​