Microsoft 365 Outage Hits Exchange Online, Disrupting Email, Calendars and Security Tools

A Microsoft 365 outage beginning November 12 disrupted Exchange Online and, through that dependency, Defender for Office 365, Purview DLP and eDiscovery, Copilot, and Teams calendar invites. Microsoft's explanation of the cause shifted several times, initially pointing to elevated load and failing health checks before citing a recent network configuration change, which it began reverting overnight. The company has said it is not aware of malicious activity behind the incident, though the root cause remained unpublished at the last check. Service was reported as recovering but not fully resolved as of November 13, with intermittent issues possibly continuing. A separate Teams incident earlier that day was resolved before the Exchange problems started, and Microsoft has not linked the two.