Microsoft 365 Outage Disrupts Email and Cloud Services

Microsoft Corporation is working to resolve a widespread Microsoft 365 service disruption that began on August 31, 2026. The outage stemmed from an issue within a core authentication configuration used across multiple services, primarily impacting Exchange Online and causing significant disruptions to Microsoft Outlook.

Thousands of enterprise customers lost the ability to send or receive emails, access calendars, and use search functionality. The disruption extended beyond email to include OneDrive for Business, SharePoint Online, Microsoft Teams, Microsoft Purview, Microsoft Defender XDR, and the Microsoft 365 Admin Center. Users reported issues with file access, synchronization, content loading, and presence indicators.

Engineers deployed a staged remediation strategy, testing fixes on portions of the infrastructure before broader deployment. While the company validated that mailbox connectivity and mail flow returned to normal by late August 31, search functionality and other features remained degraded into September 1. Microsoft has since implemented a targeted mitigation to reapply authentication components and is restarting sections of infrastructure to restore full search capabilities. Service-health telemetry shows incremental progress, though the company has not provided a final timeline for full resolution.