Microsoft Outlook Down? Microsoft Extends Email Window to 48 Hours as Millions Still Locked Out of Inboxes

Microsoft's Outlook email service stayed disrupted for millions of people around the world on Friday, the second day of a global outage. The company said it was making progress, and it had extended a key email delivery window so that delayed messages would not be lost.

The outage began shortly before 1 p.m. ET Thursday. It has left businesses, governments, banks, courts and schools in dozens of countries cut off from email, calendars and contacts. Microsoft has said there is no sign of a cyberattack, but it has not identified a root cause or said when full service will return.

"We're seeing encouraging recovery progress in Europe," Microsoft said in a status update Friday morning. It added that service in Japan was more stable and that North America was improving, though some users were still having intermittent problems.

In an update shortly after 7 a.m. ET, Microsoft still warned that users may be unable to connect to Outlook on the web or desktop, or to many other Microsoft 365 services that rely on email.

48-hour lifeline for delayed emails

To limit the damage, Microsoft extended the timeout window for incoming email to 48 hours. Normally, a message that can't be delivered within a set period may bounce back to the sender. The longer window means Outlook will keep trying to accept mail for longer, so messages sent from unaffected services such as Gmail should still arrive once the problem is fixed.

"The extended 48-hour email timeout window remains in place to help protect delayed messages as delivery catches up," Microsoft said.

The company said it had made progress restoring mailbox access and working through a backlog of delayed messages. It has not said that any messages were permanently lost.

Inboxes empty, calendars frozen

Outlook, Microsoft's email and calendar application, is used on Windows and Mac computers, on the web and on mobile phones as part of Microsoft 365. It was the hardest-hit product in the outage.

Many users could not open their mailboxes at all on Thursday. Others could not send or receive messages, and calendar invitations and meeting scheduling failed. Desktop versions of Outlook may still show emails that were downloaded before the outage.

Microsoft's consumer products were also hit. The company said the problems affected Outlook.com, OneDrive, OneNote, To Do, Teams and Microsoft 365 for the web. Outside services that connect to Outlook Calendar were also disrupted.

Reports peaked at more than 130,000

Outlook problem reports on outage tracker Downdetector peaked at more than 130,000 in the United States shortly after 1 p.m. ET Thursday. Downdetector said reports reached 74 countries and territories within about an hour.

Reports eased overnight as North American users went to bed, then climbed again as the U.S. workday approached. Around 8 a.m. ET Friday, Downdetector was still showing about 10,000 Outlook reports, a sign that the disruption was far from over.

What went wrong

Microsoft has not given a full explanation. The company said several servers became unexpectedly unavailable and that the high load on its systems was not caused by more user traffic.

As servers failed, traffic was rerouted to others, which then became overloaded. Servers that came back online were swamped by reconnection traffic and failed again. Engineers took systems offline, applied fixes and brought them back in stages.

Microsoft said early Friday that it was seeing "early signs of stabilization" but that "service capacity has not yet returned to normal levels." The company later said it was "seeing positive results for server stability after applying an upstream authentication/routing configuration component patch to a portion of our infrastructure."

"At this time, we are not aware of any malicious activity causing this incident," Microsoft said.

Charles Lamanna, Microsoft's executive vice president for Copilot, Agents and Platform, wrote on X: "We regret that today's outages caused disruptions for our customers, and we are working to address the issue."

Australian Home Affairs Minister Tony Burke said Microsoft had told him it did not believe it was facing a cyberattack. He compared the incident to the 2024 CrowdStrike outage, describing it as "an update that has gone awry."

Microsoft said it would publish a full post-incident report once the problem is fixed.

Governments and businesses scramble

The email blackout disrupted work across the globe.

Japanese government ministries went back to paper after being unable to send email for most of Friday's workday. The Supreme Court of the Philippines warned of delays. In Australia, the country's spy agency and the federal police were among those affected, and courts and schools opened to unusable inboxes.

Britain's Parliament said it was working with Microsoft and using other ways to communicate. Schools, banks and hospitals in the United Kingdom also reported problems.

In Hong Kong, staff at Morgan Stanley and Goldman Sachs were locked out of email. Indian airlines IndiGo and Akasa lost email customer-support channels. U.S. city governments, including Miami Beach and Austin, told residents to call instead of emailing.

Third-party services that connect to Microsoft 365, including AI assistants ChatGPT and Claude, reported problems with their Outlook-linked features. Microsoft's own Copilot was also disrupted.

Beware of scams

Banks including Standard Chartered and ING Australia warned customers about scammers posing as technical support during the outage. They noted that email security filters that normally catch such messages were also disrupted.

Security experts advise users not to click links or call phone numbers in unexpected messages claiming to fix Outlook accounts, and to check service status only through Microsoft's official channels.

Third major disruption this year

The outage is the latest in a series of problems for Microsoft 365. In January, the service was down across North America for almost 10 hours. In late August, thousands of Outlook users worldwide were locked out of their mailboxes.

The latest disruption has renewed calls for organisations to keep backup ways of communicating. It also comes as European leaders push to reduce their reliance on foreign technology companies.

What users can do now

Microsoft said services will come back gradually as capacity is restored and apps reconnect. Users who still can't get into their mail are advised to:

• Keep the Outlook app open, or restart it from time to time, so it can reconnect once service returns.
• Check emails already downloaded in the desktop app.
• Follow Microsoft's official service status pages for updates.
• Contact important people by phone or another platform while email remains unreliable.

IT administrators can follow incident updates through the Microsoft 365 admin centre's service health dashboard.

Microsoft has not given a timeline for full recovery.