Widespread Microsoft 365 Outage Disrupts Exchange Online Email and Authentication
Microsoft is investigating a widespread service outage causing authentication issues, connection problems, and service failures for Microsoft 365 customers worldwide. The company first acknowledged the incident, tracked as EX1464935 in the admin center, at 5:30 PM UTC after a flood of reports from users on social media. According to outage tracking service Downdetector, tens of thousands of Outlook and Microsoft 365 users are experiencing problems receiving emails and accessing Microsoft cloud services.
While Exchange Online is the most impacted service, Microsoft reveals in a follow-up incident report that the outage also affects OneDrive for Business, SharePoint Online, Microsoft Teams, Microsoft Purview, and Microsoft Defender XDR. Symptoms include delays or failures when sending or receiving email, incomplete search results within mailboxes, authentication-related errors, difficulties accessing Exchange admin experiences, and intermittent failures affecting mailbox operations and message delivery workflows.
Microsoft says it has isolated a common failure pattern across affected Exchange Online requests that is associated with authentication and protocol connectivity. Engineers are analyzing service telemetry to identify the underlying source and validate potential remediation options while continuing to assess the scope of impact. This is the latest in a series of Exchange Online outages Microsoft has addressed in recent months, including a June mail flow disruption and April mailbox access issues affecting Outlook mobile users.