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A widespread technical outage affecting Microsoft 365 services has disrupted emails, messaging, and artificial intelligence tools worldwide, impacting schools, courts, healthcare systems, and government agencies. The disruptions began on Thursday, causing intermittent access issues across key platforms such as Outlook, Teams, and Copilot.
Global Impact and Scope of the Disruption
Microsoft 365 serves more than 430 million users globally. While the full scope remains unconfirmed, tracking website Downdetector recorded over 140,000 reports from 74 countries on Thursday evening. The actual number of affected users is expected to be significantly higher due to self-reporting limitations. The disruption also created ripple effects for other technology firms, including artificial intelligence developers OpenAI and Anthropic, which reported connectivity problems with Microsoft’s infrastructure.
The outage affected operations internationally. In the United States, courts from Los Angeles to Texas warned of communication delays, and several city governments faced technical difficulties. Australian intelligence agencies and Japan’s shared government IT platform were also disrupted. In Canada, public broadcaster CBC reported email issues across a major hospital network in Toronto, though patient care was not affected. Across the United Kingdom, police forces, pharmacies, schools, and GP surgeries experienced issues, prompting some medical practices to request that patients refrain from submitting online inquiries while services were down.
Cause and Technical Recovery Efforts
Microsoft ruled out a cyber-security attack, attributing the failure to an “elevated load” on its system infrastructure. According to the company, a significant number of servers became unexpectedly unavailable, forcing remaining servers to handle excessive traffic volumes. To protect delayed messages, Microsoft extended its email timeout window to 48 hours, noting that delayed emails would display delivery timestamps based on when they arrived rather than when they were sent.
By Friday afternoon, the company reported encouraging recovery in Europe and improvements in North America, with email queues returning toward normal levels. However, officials warned that intermittent connection issues might persist as restoration efforts continue.
Why Restoration Has Taken Time
With disruptions lasting over 20 hours, technical experts highlighted the complexity of restoring massive cloud infrastructure. Computer science professor James Ferryman from the University of Reading explained that when server components managing secure connections become overwhelmed, they stop responding. This triggers a snowball effect where traffic transfers to remaining servers while millions of disconnected devices continuously attempt to re-establish access, requiring systems to be brought back online gradually to avoid another crash.
Former tech software engineer Gergely Orosz noted that the incident could mark the most disruptive business email outage in history, citing the unprecedented duration for such a core service. Speaking to BBC News, cyber-security expert Troy Hunt emphasized that Microsoft forms a central part of the internet’s backbone, noting that the outage highlights how essential email remains for critical daily operations, appointment scheduling, and account verification.
