Microsoft has made progress in restoring services after a global outage disrupted Outlook, Teams, Copilot and other Microsoft 365 tools, although some users continued to face intermittent access problems and delayed emails on Friday 13 November.
The company said mailbox access had improved across North America and that queues of delayed messages were approaching normal levels. Recovery was also reported across much of Europe, with encouraging signs in the Asia-Pacific region.
Microsoft extended the delivery window for emails caught in the backlog until at least Saturday afternoon, giving delayed messages additional time to reach their intended recipients before being marked as undeliverable.
Microsoft outage linked to network capacity issue
The disruption began on Thursday and spread to users in 74 countries and territories within about an hour, according to outage-tracking service Downdetector. At its peak, about 130,000 reports of problems accessing Outlook were recorded in the United States.
Microsoft said the incident was caused by a technical problem rather than a cyber attack or artificial intelligence. The company linked it to an issue introduced during an earlier network capacity upgrade that surfaced after a more recent network change.
Several servers went offline, leaving the remaining infrastructure under elevated load. Some servers initially appeared to have recovered but became unresponsive again when traffic returned, complicating attempts to restore the affected systems.
“We are deeply sorry for the disruption this incident has caused our customers and partners,” Microsoft said. “We know the trust they place in our services and take that responsibility extremely seriously.”
The company said engineers were restoring services gradually, testing stability at each stage and adding capacity where necessary. It said the slower approach was intended to prevent further instability as demand returned across the network.
Microsoft said it would publish a full post-incident report once its review had been completed.
The outage affected more than email. Users reported difficulties with Teams, Copilot, Microsoft To Do, Planner and parts of the Microsoft 365 administration and security services. Core Teams functions, including calls and meetings, were generally less affected than features dependent on Exchange Online.
In the UK, the Government said it was working with Microsoft to assess the impact on public services and had contingency arrangements in place. Some police forces said they were unable to receive crime reports online and urged people to use emergency telephone services for urgent matters.
Microsoft had not given a firm timetable for the full restoration of every affected service, but said it was continuing to monitor recovery across regions and work through remaining email backlogs.
