On Thursday, Microsoft Outlook had a big outage that stopped tens of thousands of users from checking email. The problem lasted most of the workday, so many people could not send or receive messages.

Microsoft said the outage was caused by “elevated load” on its infrastructure, which led to connectivity errors. Downdetector reported that the disruption affected Microsoft 365 services, including Outlook, Teams and Copilot, in 74 countries and territories.

Downdetector recorded about 130,000 U.S. users reporting Outlook issues just after 1 pm Eastern Time. By 6 pm, the reports fell to around 37,000, but the delay still disrupted many work tasks and meetings.

Microsoft said it paused all deployments, moved additional traffic off the affected infrastructure, and restarted affected servers to restore service. The outage shows how a single service problem can pause work for many people around the world.