Microsoft first acknowledged that users in the Americas were unable to access Exchange Online mailboxes at 17:54 GMT on Thursday, and shortly after warned that the disruption may have been affecting Microsoft 365 globally.
While investigators were deployed and engineers began work to restore services, by 04:36 on Friday Microsoft reported only a partial recovery in some regions.
By 13:32, the company reported broader improvements in North America, sustained improvements across much of Europe, and encouraging recovery signals in the Asia Pacific region.
Microsoft said it restored services incrementally due to the scale of the problem, aiming to keep stability once services are back online.
“We are deeply sorry for the disruption this incident has caused our customers and partners,” a Microsoft spokesperson said.
“We know the trust they place in our services and take that responsibility extremely seriously.”
Microsoft has not provided an estimated time (ETA) for when services will be fully recovered.
A comprehensive post‑incident report will be published after Microsoft completes its review of the event.
Industry experts noted that while employees may have been relieved not to have email for the day, the outage highlighted how many organizations rely on cloud‑based services.
“The worldwide Microsoft outage serves as a stark reminder of how heavily enterprises depend on a handful of major technology providers,” said Rob Demain, chief executive of cybersecurity firm e2e‑assure.
Matt Saunders, field CTO at tech consultancy Adaptavist, said it would be challenging to mitigate against a similar problem.
“Classic IT disaster‑recovery planning recommends using a secondary service for resilience, but in practice it is almost impossible for a business to operate without tools like Microsoft,” he noted..
Organizations should now ensure they have contingency plans for operating without such tools when similar incidents occur.