Hours-Long Email Service Failure Impacts Millions of Users Worldwide
A widespread Microsoft Outlook outage that began on Wednesday evening has stretched into Thursday, leaving millions of users worldwide unable to access their emails, calendars, and other essential services. The disruption has affected all versions of Outlook, including the web application (Outlook.com), mobile apps, and desktop clients.
Microsoft acknowledged the issue on their service status page, stating that "users may be unable to access their mailbox using any connection methods." The tech giant has identified the root cause as an issue with "mailbox infrastructure not performing as efficiently as expected" and has been working on deploying fixes throughout the day.
"We've begun a broad expedited deployment of the configuration change across all affected infrastructure. We expect most impacted users will experience relief within the next two hours, as the fix saturates the environment."
— Microsoft 365 Status Update
Microsoft has deployed configuration changes that are gradually resolving the issue. Some users have regained access, while others continue to experience disruptions.
Last updated: July 10, 2025 - 5:00 PM EDT
Initial reports of Outlook access issues begin appearing on social media and outage tracking websites.
Microsoft confirms the outage on their service status page, acknowledging that users may be unable to access their mailboxes.
Microsoft identifies that a portion of mailbox infrastructure isn't performing as expected and suspects an authentication component issue.
Engineers determine the root cause and begin deploying a fix, warning that it will "take an extended period following our safe change management process."
Microsoft reports that the deployment is "progressing quicker than anticipated" and expects impact to gradually mitigate.
Reports on DownDetector peak with over 2,400 users reporting issues. Microsoft identifies an issue with the initial fix and deploys a corrected version.
Microsoft announces that "configuration changes have effectively resolved impact in targeted infrastructure" and begins worldwide deployment.
The prolonged outage has caused significant disruption for businesses and individuals who rely on Outlook for daily communications. Many organizations reported workflow delays and communication challenges, particularly as the outage coincided with the start of the workday in the United States.
Users expressed their frustration on social media platforms, with many complaining about the lack of detailed information about the cause and resolution timeframe. A user from Manchester reported trying to log in five times, only to be repeatedly kicked out, stating, "I need access for work, this is beyond frustrating."
While Outlook services were down, Microsoft confirmed that other Microsoft 365 services, including Teams and OneDrive, continued to operate normally, indicating that the issue was isolated to Outlook's email servers.
This is not the first major outage to affect Microsoft services in recent months. The company has experienced several significant disruptions that have impacted its user base:
Outlook.com users on iOS couldn't access their messages via Apple Mail for over a week, causing significant frustration for iPhone and iPad users.
Issues emerged specifically on virtual desktop infrastructure, affecting enterprise users who rely on the Classic Outlook client.
Users reported problems accessing Exchange Online and functionality within Microsoft Teams calendar, disrupting meeting scheduling and attendance.
Thousands of users were unable to sign into their email accounts or access other Microsoft 365 applications for several hours.
A defective update from cybersecurity software company CrowdStrike crashed Microsoft Windows systems globally, affecting critical infrastructure including hospitals, banks, and emergency services.
Technology experts point out that as businesses become increasingly dependent on cloud services, outages like this highlight the vulnerabilities in our digital infrastructure. While cloud services generally offer high reliability, when they fail, the impact can be far-reaching and significant.
Cybersecurity analysts have noted that there is no indication this outage is related to any security breach or cyberattack. Instead, it appears to be a technical issue related to Microsoft's authentication systems and mailbox infrastructure.
"This outage serves as a reminder for organizations to have contingency plans for critical communication systems. Relying solely on one provider, even one as established as Microsoft, carries inherent risks in today's interconnected business environment."
— Technology Analyst
Microsoft has not provided detailed information about what specifically caused the mailbox infrastructure issues, but the company's focus on authentication components suggests the problem may be related to how users' credentials are verified when accessing the service.
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