Microsoft has ruled out a cyberattack as the cause of a major global outage disrupting its Microsoft 365 services, including Outlook, Teams and Copilot, as the technology company continues efforts to restore normal operations across affected regions.
The disruption, attributed to infrastructure strain and server unavailability, has affected users’ ability to send and receive emails, access files and use calendar applications, while businesses and public institutions across several countries have reported operational challenges.
Microsoft said the outage resulted from elevated load on its infrastructure after a number of servers became unexpectedly unavailable, redirecting additional traffic to the remaining servers and placing further pressure on the system.
The company said its initial recovery efforts had not produced the expected results, although it later reported improvements in Europe and North America.
In an update on Friday, Microsoft said, “We have seen encouraging recovery progress” in Europe, alongside improvements in North America, while efforts continued to address the remaining areas of disruption.
The company, however, warned that “some users may still experience intermittent issues as recovery actions continue”.
The scale of the disruption remains uncertain, although Downdetector, an online service-monitoring platform, recorded reports from approximately 140,000 users across 74 countries experiencing Outlook-related problems on Thursday evening.
The actual number of affected users is likely to be higher, as Downdetector’s figures are based primarily on voluntary reports from individuals experiencing service disruptions.
Microsoft 365 has more than 430 million users globally, according to information published on the company’s website, highlighting the potential scale of the disruption to businesses and individuals relying on its productivity and communication applications.
The outage has also affected other technology companies dependent on Microsoft’s infrastructure. OpenAI, the developer of ChatGPT, said it was investigating an issue affecting its connections to Microsoft’s services, which had caused some of its tools to not work as expected.
Anthropic also reported service-related problems linked to the disruption.
Beyond the technology sector, the outage has affected public institutions and essential services across several countries, including government agencies, healthcare providers, police departments, schools and businesses.
In the United Kingdom, general practitioner surgeries, pharmacies, police forces and schools reported disruptions, with some healthcare providers advising patients against using online messaging services until the issue was resolved.
In Canada, the public broadcaster CBC reported that a healthcare network operating several hospitals in Toronto experienced email difficulties, although patient care was not affected.
Japan’s government also reported disruption to its shared information technology platform, while courts in Los Angeles and Texas in the United States warned that communications could be delayed.
Australian cyber-security expert, Troy Hunt, told the BBC that the outage could have far-reaching consequences.
“Microsoft is a massive part of the internet backbone and reminds us how critical email still is,” he said.
Hunt added that the disruption affected not only people’s ability to work but also their capacity to communicate about appointments, purchase items requiring verification and access accounts and other services.
A former software engineer at technology companies including Skype and Uber, Gergely Orosz, described the incident as potentially the “most disruptive” business email outage “of all time”.
He said it was still difficult to establish the number of people affected but added that he cannot recall a business email outage taking so long to return to normal.
Paul Spain, of New Zealand-based advisory firm Gorilla Technology, said businesses affected by the outage had practically “lost a business day”, describing the situation as frustrating for users.
For organisations using Microsoft 365 as part of their daily operations, prolonged service disruptions could delay transactions, affect customer engagement, interrupt internal communication and increase operational costs.
Although Microsoft has reported progress in restoring affected services, the continuing possibility of intermittent disruptions means businesses may still face challenges until the company fully stabilises its infrastructure.
