Microsoft's email service, Outlook, faced a major outage on Thursday, November 12.
Users around the world could not send or receive emails for hours.
Microsoft said the problem came from a high "elevated load" on its infrastructure across several regions.
In simple words, too much work landed on some servers, and several of them stopped responding.
Its other products, Teams and the AI assistant Copilot, were also hit.
So why does this matter for you? If you use Outlook for office work, delayed emails can hold up replies and meetings.
Key points
- Outlook, Teams and Copilot had problems on Thursday, November 12.
- An outage tracker, Downdetector, recorded reports from 74 countries and territories.
- Microsoft says it is restarting servers and moving traffic to restore full service.
- The exact cause of the outage is not yet known.
What caused the outage?
Microsoft said a part of its infrastructure was under heavy load across multiple regions.
This was likely causing the connection errors users saw.
In another message, the company said a number of servers were unexpectedly unavailable.
It said the extra load was not caused by a rise in traffic.
The company has collected networking logs to find the source of the errors. It has not yet confirmed the exact cause.
How many users were affected, and where?
Downdetector counts problem reports sent by users, so it shows how many people faced trouble.
It does not give the exact number of affected accounts.
Reports for Outlook peaked at 138,058 around 1pm US Eastern Time. By 6pm Eastern Time, the number had fallen to about 37,000.
- Thursday, November 12Outlook outage hits users worldwide, and email sending and receiving fails for hours.
- 1pm US Eastern TimeOutlook problem reports peak at 138,058 on Downdetector.
- 6pm US Eastern TimeReports fall to about 37,000, and Microsoft says it is seeing limited recovery.
- Friday, 7.05am (Singapore)The tracker records 250 Outlook problem reports in Singapore.
Graphic: News Anek, from the facts in this report
In Singapore, the tracker recorded 250 reports for Outlook at 7.05am on Friday.
Governments and organisations, including the State of Michigan in the United States, were also affected.
Is email working normally now?
Not fully yet. At 6pm Eastern Time, Microsoft said it was seeing limited recovery.
It said users may slowly reconnect as capacity is restored.
Microsoft says it has paused all deployments and is restarting affected servers.
It is also moving traffic away from the affected infrastructure.
