Microsoft Apologizes for Massive Outlook Outage, Affected Customers Can Request Credits for Service Interruption

Microsoft issued an apology Friday for a worldwide outage of its email servers that left millions of Outlook users without access to their mailboxes starting Thursday in some cases for more than 18 hours.

“We are deeply sorry for the disruption this incident has caused our customers and partners. We know the trust they place in our services and take that responsibility extremely seriously. We are seeing broad recovery and stability across our services,” the company said in the statement shared at 8:40 a.m. Pacific.

Customers affected by the Outlook outage may be eligible to receive credits for the downtime. According to information on the company’s partner center help site, service level agreement (SLA) credits from Microsoft are determined based on which services were affected, and credits are prorated based on the service affected and the duration of the outage. In addition, those submitting credit requests must “provide evidence that the outage affected the customer” and that the “customer email submitted as evidence must come from the domain of the affected tenant. (Email from a personal address isn’t acceptable).”

In its statement, Microsoft reiterated that the outage was not the result of a cyberattack and also said it was unrelated to AI agents.

“This was a technical issue not related to cyber or AI / agents. The incident was introduced by an issue during an earlier network capacity upgrade that surfaced following a recent network change,” Microsoft said. “We have addressed the underlying issue and continue to restore service to remaining customers and regions. Given the scale of demand, we restored services gradually, validating stability at each stage. While this took longer, it helped ensure a stable restoration. We will provide a full post-incident report once our review is complete.”

The problems started affecting Outlook users, and those of other Microsoft 365 services including Microsoft Teams, at around 12:30 p.m. ET on Nov. 12. Service began to be restored Friday morning, starting in the Asia Pacific region then extending across Europe and North America.

Microsoft said in January that Microsoft 365 commercial seats grew 6% year-over-year to over 450 million for the quarter ended December 2025.