Microsoft Exchange outage disrupts Outlook and Microsoft 365 for over 100,000 users

Microsoft reported problems with Microsoft Exchange Online, the backend cloud service for Outlook, causing a major outage on Thursday that disrupted access to email and other Microsoft 365 tools for over 100,000 users. Exchange Online is the server that stores data, manages mail flow, syncs information to Outlook, and enforces security policies. While Outlook is the user-facing front end, Exchange is the backend, meaning users experienced the same result: inability to access email, calendars, or messages. Microsoft has posted updates on X but had not responded to media inquiries as of Thursday. The outage affected the broader Microsoft 365 suite, including Teams and Copilot, though the company attributed the root cause specifically to Exchange.