Overview

• An outage that began at 22:20 UTC on July 9 has left millions of Outlook users worldwide unable to access their mailboxes on web, mobile and desktop platforms for over 11 hours.
• Microsoft’s Service Health page cites underperforming mailbox infrastructure and a faulty authentication component as the root causes and confirms a staged fix deployment.
• Down Detector reports show 62 percent of incidents involve login failures, 34 percent relate to server connection errors and 5 percent to email-sending issues, with many users also receiving invalid-license warnings.
• Microsoft says the fix deployment is progressing faster than anticipated and expects the outage impact to gradually subside ahead of its next status update.
• Core Microsoft 365 services including Teams, Skype and OneDrive have remained operational, but this marks the second major Outlook interruption this year, raising questions about the service’s resilience.