Microsoft Outlook outage cause seemingly revealed

November 12, 2026

IT worldwide outrage on 19th July 2024, blue screen on laptop. Photo is made in Spain, Marbella - stock photo

Updated on Thursday, Nov. 12 at 5:26 p.m. ET — Microsoft services remained down on Thursday evening, as Microsoft acknowledged ongoing problems in an update posted to X.

The Microsoft global outage has affected Outlook, Teams, and other Microsoft 365 services, starting around 12:30 p.m. ET.


If Outlook wouldn't load for you on Thursday, Microsoft now has a theory about what went wrong. The company said in an X post on Nov. 12 that a component responsible for checking whether its servers are working properly may be behind the failures that took some servers out of service.

If Outlook wouldn’t load on Thursday, Microsoft now has a theory about what went wrong. The company said on Nov. 12 the failed health checks "may originate from a specific component on the affected servers" that runs those checks.

In its service health update, Microsoft said some servers went offline after failing automated health checks. With parts of its infrastructure under heavier load than usual across multiple regions, the company said that extra strain was likely contributing to connection problems.

This Tweet is currently unavailable. It might be loading or has been removed.

Microsoft also says it’s "deploying a targeted change to bypass this component on a subset of servers" to see if that brings them back online. It has also taken steps to keep more servers from going out of service. So far, Microsoft says it hasn’t found a recent change that coincided with the start of the outage. The company is still investigating why the checks failed.

Microsoft initially flagged trouble accessing Exchange Online mailboxes in the Americas. Exchange Online is the service that stores and delivers email for many Outlook users.

This Tweet is currently unavailable. It might be loading or has been removed.

The company later warned that the issue "may affect Microsoft 365 service connectivity for users in any region." Around 1 p.m. ET, nearly 130,000 Outlook problem reports appeared on Downdetector, and users reported trouble loading their inboxes and sending or receiving emails. Copilot users also reported problems.

This Tweet is currently unavailable. It might be loading or has been removed.

Earlier Thursday, Microsoft had also flagged problems with Teams in North America under incident TM1550488. In a follow-up on X, the company said its automated recovery systems had kicked in and were reducing the disruption.

Microsoft is posting updates under EX1550543 and MO1550821 in the Microsoft 365 admin center. If the admin center is also out of reach, Microsoft is directing users to its public service status page.

This Tweet is currently unavailable. It might be loading or has been removed.

This is a developing story...

Want more tech and digital culture news delivered to your inbox daily or sent straight to your device? Sign up for Mashable's Top Stories newsletter or get Mashable push alerts today.

Previous Article
Is Outlook down? Possible Microsoft outage locks down email inboxes.
Is Outlook down? Possible Microsoft outage locks down email inboxes.

On Thursday, Nov. 12, Outlook users reported a Microsoft outage that prevented them from checking their ema...

Next Article
What is Microsoft Exchange? The cloud tool behind Microsoft Outlook issues.
What is Microsoft Exchange? The cloud tool behind Microsoft Outlook issues.

Microsoft has reported problems with Microsoft Exchange Online, which would explain why so many users are r...