Microsoft apologizes for 18 hour Outlook outage

Millions of Outlook users lost access to their mailboxes during a global outage that started on Thursday, November 12, and lasted more than 18 hours for some. Microsoft issued a formal apology on Friday, November 13, acknowledging the disruption to its email infrastructure and other Microsoft 365 services.

The failure began at approximately 12:30 p.m. Eastern Time. Service restoration started on Friday morning in the Asia Pacific region before expanding to Europe and North America. Microsoft stated that broad recovery and stability have been observed across its platforms. The company attributed the failure to a technical issue introduced during an earlier network capacity upgrade, not a cyberattack or its artificial intelligence agents.

Affected customers are eligible for service credits, but the company will not apply these funds automatically. Users must submit a verified request that documents the specific disruption they experienced. The value of the credits is prorated based on the duration of the outage and the particular service impacted.

The company requires specific evidence to qualify for compensation. The email address submitted as proof must originate from the domain of the affected tenant. Emails sent from personal addresses are not accepted as valid proof of impact. Credits are calculated according to the service level agreements detailed on the partner center help site.

Microsoft explained that it restored services gradually to ensure stability at each stage of the rollout. This cautious approach extended the total restoration time but helped prevent further instability. A full post incident report will be provided once the internal review is complete.

The outage occurred while demand for Microsoft commercial platforms continued to grow. The company reported that Microsoft 365 commercial seats increased by 6 percent year over year in January. The total number of seats reached over 450 million for the quarter that ended in December 2025.