Microsoft 365 outage: Outlook is down. What we know.

Updated on Jan. 22 at 5:31 p.m. ET: Microsoft said it was working toward fixing a 365 outage on Thursday, though noted users may still be experiencing issues.

"We're carefully rebalancing traffic across all affected infrastructure in the region," read a statement on its 365 status page. "We’re proceeding as quickly as possible and this incremental approach will also help us identify whether any additional actions may be required to ensure longstanding recovery."

Microsoft 365 suffered an outage on Thursday, affecting U.S. users going about their workday.

"Users may be seeing degraded service functionality or be unable to access multiple Microsoft 365 services," the company wrote on its 365 status page.

Microsoft users reported being unable to send or receive email through Outlook, and services such as Teams and Defender may also be affected. Ironically, even the Microsoft 365 status page is having trouble loading for some users.

"Users may be receiving a '451 4.3.2 temporary server issue' error message when attempting to send or receive email through Outlook," read the Microsoft status page.

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User-reported issues for Microsoft 365 spiked on Downdetector on Thursday afternoon. The reports appeared to be going down as evening, Eastern time, approached. (Disclosure: Downdetector is owned by Ziff Davis, the same parent company as Mashable.)

Microsoft noted it was working toward restoring services.

"While we've restored the affected infrastructure to a heathy state, further load balancing is required to mitigate persistent impact," read its 365 status page. "We've identified and are implementing additional actions to direct requests and traffic to additional healthy sections of infrastructure to achieve withstanding recovery."

Not being able to send or receive emails is, obviously, a major pain for workers. Lots of folks took to social media to voice their frustrations and, of course, make jokes.

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Microsoft has been no stranger to outages lately. It saw two major outages in October alone, with both 365 and Azure crashing that month. There was also the infamous, massive outage in 2024, ultimately caused by an issue with the cybersecurity provider CrowdStrike.

This story is developing and will be updated as necessary...