According to the article, a multi-day outage affecting customers’ access to Outlook email and other Microsoft 365 services entered its second day, with the company making significant progress in addressing the issue on Monday. The outage was caused by a problem impacting the Exchange Online service, leading to email delays, authentication issues, and other problems for some Outlook users. However, as of Tuesday, the issues were not fully resolved, with Microsoft stating that its “mitigation actions are continuing to progress.”
The outage also affected other services, including SharePoint, Copilot, Teams, Purview, Defender XDR, the Microsoft 365 Admin Center, and Universal Print, due to an issue with a “core authentication configuration” used by multiple Microsoft 365 services. The company identified the problem as a misconfiguration that prevented authentication components from deploying as expected to a portion of the infrastructure. Over time, as mitigations were rolled out, users began to see gradual recovery in mail flow, with search functionality improving shortly after 3 a.m. ET on Tuesday. While indications from telemetry were positive and service availability was improving, the article notes that the service had not yet returned to normal, and the company was entering a period of extended monitoring to ensure a full resolution. Source