Microsoft’s popular email service, Outlook, experienced a major outage lasting several hours from Wednesday evening into Thursday, disrupting access for millions of users worldwide. The interruption affected not only the web-based Outlook.com platform but also the desktop and mobile applications, leaving many unable to check or send emails during the downtime.
The problem began at approximately 6:20 p.m. Eastern Time on Wednesday, according to Microsoft’s official service health dashboard. Users across various regions reported encountering error messages such as “something went wrong” and difficulties logging in, with some receiving notifications about invalid licences. The outage impacted a wide range of users, from individual consumers to businesses relying heavily on Outlook for daily communications.
By midday on Thursday, Microsoft announced via its Microsoft 365 Status account on X that a fix was being rolled out.
“Our configuration changes have effectively resolved impact in targeted infrastructure. We’re now deploying the changes worldwide to resolve impact for all users,” the company stated.
The official status page reassured users that “most impacted users will experience relief within the next two hours,” while engineers continued to monitor the situation closely.
Microsoft later revealed that the root cause of the disruption was linked to underperforming mailbox infrastructure, specifically an authentication component that failed to function correctly. This issue led to widespread authentication failures, preventing users from accessing their mailboxes. The company confirmed it was conducting a thorough investigation to prevent similar incidents in the future.
The outage sparked considerable reaction on social media, with users sharing screenshots of error messages and expressing frustration over the prolonged service interruption. Many businesses experienced operational delays, displaying Outlook’s importance as a communication tool in professional environments. By Thursday afternoon, reports indicated that the service was gradually returning to normal.
Outlook remains a key component of Microsoft 365’s productivity suite, serving hundreds of millions of active users globally. However, it faces stiff competition from other major email clients. Analytics firm Litmus data shows that Apple’s Mail app and Google’s Gmail hold larger shares of the email client market, particularly among mobile users. Despite this, Outlook’s deep integration with enterprise software and widespread corporate adoption continue to make it a critical service for many organisations.
This outage is not an isolated event. Microsoft Outlook has faced several disruptions over the past year, including a notable outage in June and an eight-day disruption in March that affected iOS users accessing Outlook via Apple Mail. These recurring issues have raised concerns about the platform’s reliability and prompted Microsoft to invest in infrastructure upgrades.
In response, Microsoft has pledged to improve the resilience of its email services, emphasising its commitment to maintaining high availability and minimising downtime. Efforts underway include upgrading authentication systems, enhancing monitoring capabilities, and refining incident response procedures.