Ing. Calogero Bono
From Thursday, November 12, Microsoft 365 suffered a global outage that hit Outlook, Teams, SharePoint Online and Copilot. Hospitals, schools, courts and public offices worked at a crawl. Services are gradually coming back online, but the official cause is still unknown. For anyone working in the cloud, it is a concrete reminder of the price of depending on a single provider.
A few terms before we get into the facts. Azure VNet is Microsoft's cloud virtual network, which connects services to each other. Exchange Online is the Microsoft 365 email service. Post-incident report is the technical report the company publishes at the end of an emergency, explaining the cause. Single point of failure is a single point of breakdown – if it gives way, everything stops. Redundancy means having a second system ready to replace the first.
What happened to Microsoft 365?
According to Engadget the problem began on Thursday afternoon and involved Outlook, Teams and Copilot 365. For The Register, Microsoft indicated the start at 18:26 GMT on November 12, calling it a «Service Degradation». It also involved Exchange Online and Microsoft 365 Education.
We had already written about it when Exchange Online had been down for over 12 hours. The situation then worsened into a disruption lasting almost two days, as The Verge reports.
What is the cause of the outage?
There is no official cause yet. Microsoft says it has no evidence of malicious activity and speaks of a «technical problem», not linked to cyberattacks, AI or DDoS. It promises a report with the cause once the emergency is over.
Tom Warren of The Verge, citing his own sources, links it to configuration changes in Azure VNet. It is a rumor, not a confirmation. Ars Technica headlines on failed server health checks, but the available text mainly says Microsoft was caught off guard. We covered the case as well in this article on servers going down.
How did Microsoft work to restore the services?
Engadget reports that around 22:00 ET on Thursday some attempts to improve the situation had not worked. By 2:45 in the morning Microsoft was seeing positive results after traffic optimization actions. Then improvements arrived in North America, much of Europe and encouraging signs in Asia Pacific.
To avoid losing messages, Microsoft extended the mail timeout to 48 hours, as Ars Technica reports. Some emails may still arrive late and the connection may remain unstable.
Who suffered the most damage?
Ars Technica mentions hospitals, police, schools, banks and courts. Some doctors could not send updates on therapies, and some customers did not receive the verification codes for bank transfers. In Japan, government systems were hit. Ciaran Martin, former head of the British National Cyber Security Centre, called it, according to the article, «one of the biggest outages ever».
In January Microsoft estimated over 450 million paid commercial subscriptions. How many users were affected is not clear.
Limits to know
The final report is missing, so the cause remains a hypothesis. We do not know how many users lost data or emails, nor whether refunds will be offered. The sources use different times and time zones, and not all confirm the same details. Even the total duration varies, from a full day to almost two days, and could be revised.
What changes for those who work digitally
If your company runs on Microsoft 365, email and collaboration are a single point of failure. Ask yourself what happens if Outlook is down for 24 hours and who can contact your clients in that case. An alternative channel, for example WhatsApp for business, helps you stay reachable. Also consider whether the comparison between Google Workspace and Microsoft 365 should be redone with resilience in mind.
Our take
An outage can happen to anyone, and even Microsoft's rivals say so. The real issue is concentration. Many businesses and institutions have put email, documents and chat in the same place, often without a backup plan. The return to fax machines in Japan and Germany makes for a smile, but it shows that a manual backup plan exists only if it is prepared in advance. We are waiting for the report, but without transparency, apologies alone will not be enough.
Frequently asked questions
Is the Microsoft 365 outage over?
Almost. Microsoft speaks of a gradual recovery, but some users may still have delayed emails or unstable connections. The sources describe the restoration as progressive.
Was it a hacker attack?
Microsoft says no. It has found no evidence of malicious activity and describes a technical problem. The final report should confirm this.
Did I lose the emails sent during the outage?
Probably not. Microsoft extended the mail timeout to 48 hours to keep delayed messages. It is not, however, an absolute guarantee for every mailbox.
Which services were affected?
Outlook, Exchange Online, Teams, SharePoint Online, Copilot and the 365 apps. Microsoft 365 Education was also involved.
How can I reduce the risk of another shutdown?
Zero risk does not exist. You can have an alternative contact channel, local copies of key documents and a written procedure for days of disruption.
Microsoft's report and the consequences for contracts and trust
In the coming weeks, the official cause and the promised actions will matter. From there you will understand how much the risk also concerns your company.
- Read the post-incident report as soon as it comes out and check whether the cause involves network configurations.
- Check the service terms and any right to credits before renewing.
- Run an emergency drill, a working day without Microsoft email and chat.
Sources
- engadget.com, Microsoft services are returning after an outage took down Outlook, Teams and more
- theverge.com, Microsoft’s massive Outlook outage continues
- theregister.com, Microsoft outage gives customers a crash course in dependence on Redmond
- arstechnica.com, Microsoft’s global outage may be worse than Amazon's or CrowdStrike's, expert says
