Outage at Microsoft 365: what happened and what you can learn from it

On Thursday afternoon, November 12, things went wrong at Microsoft. Worldwide, millions of people could no longer send or receive email via Outlook, calendars in Teams stopped working, and Copilot and SharePoint also had problems. It wasn't until Friday evening that most people could work normally again. In this article, we outline what happened, what you should check right now, and why this outage is a good moment to take a critical look at your own dependency.

What happened?

1. Outage beginsThursday, November 12, 17:15

   Exchange Online servers unexpectedly become unreachable. Because many other Microsoft services rely on this, they also go down: calendars and meeting scheduling in Teams, Copilot, SharePoint, the admin environment for IT administrators, and part of the security software.

2. WorldwideThursday, November 12, 19:00

   Downdetector now shows more than 130,000 reports about Outlook. Businesses, schools, and governments in Europe, North America, and Asia are without mail. Microsoft states there are no indications of a hack.

3. Problems againFriday, November 13, morning

   Servers that Microsoft had restored overnight go down again. To prevent delayed mail from being lost, Microsoft extends the time mail is allowed to keep waiting to 48 hours. The National Cyber Security Centre (NCSC) publishes advice for organizations.

4. Largely resolvedFriday, November 13, evening

   In large parts of Europe and North America, everything is working again. The exact cause is not yet known. Microsoft is investigating whether a change in the network, around the start of the outage, was the culprit and has promised a full report.

What should you check now?

Do you use Microsoft 365 yourself, or do you work with clients or suppliers who do? Then take a moment to go through these points. The NCSC points out that Microsoft's security scans were delayed or incomplete during the outage.

1. Watch out extra for phishing. Criminals love to use outages as an excuse. Emails asking you to change your password or "restore" your account are extra suspicious for the time being, even if they appear to come from Microsoft.
2. Be careful with attachments that arrived between Thursday afternoon and Friday evening, especially from senders you don't know.
3. Check whether important mail has arrived. Mail may have been delivered hours later or sent back. Did you send quotes, invoices, or orders to someone with a Microsoft address? Then check with them to make sure it arrived.
4. Check your spam folder and quarantine. When the filters started up again, mail may have been blocked incorrectly.

The real problem: everything with one provider

Outages happen with every provider. With us too, we're honest about that. What made this outage so big is that many companies have placed everything with Microsoft: email, calendar, chat, files, login, and security. If one component goes down, the entire company comes to a standstill. You can't just switch over for a bit, because everything hangs on the same account.

You can't prevent an outage. But you can make sure one outage doesn't bring your entire business to a halt.

And switching over? That turns out to be more difficult than expected. In early November, Leaseweb asked 800 executives in the Netherlands, Germany, the United Kingdom, and the United States how quickly they could leave their largest cloud provider. 89 percent cannot do so within three weeks. Dutch companies are the most pessimistic: 65 percent think they would need more than three months. Leaseweb is itself a cloud provider and paid for the research, but the picture is clear: most companies are stuck.

On top of that, Microsoft is an American company, subject to American legislation. You can read what that means for your privacy in our earlier article Outlook: a privacy nightmare. If you use the new Outlook for a mailbox hosted with us, by the way, your mail also runs via Microsoft's servers. So you're still dependent on Microsoft, even if your email is hosted elsewhere.

How do you make your business less vulnerable?

Use an email address on your own domain name. This is the most important step and costs almost nothing. With an address like you@yourcompany.nl, you decide where your mail arrives. If you want to switch to another provider, you just adjust a few settings in your DNS and your address simply stays the same. With an address like yourcompany@outlook.com, that's never possible: your customers, suppliers, and accounts are permanently tied to Microsoft.

Spread your services. You don't have to overhaul everything at once. But if your mail, files, and website aren't all hosted with the same provider, one outage won't immediately bring everything down. If you can't send mail, you can at least still access your files. And vice versa.

Know how you can leave. Make sure you know where your mail, contacts, calendar, and files are stored and how to make a copy of them. A switch you've already thought through goes much faster in an emergency.

Choose European wherever possible. There are full-fledged alternatives that run in Europe and that you control yourself. With us, that's email hosting on your own domain name and Nextcloud for files, calendar, and contacts, with Euro-Office for working together on documents, spreadsheets, and presentations. Everything runs on our own servers in the Netherlands.

Our mail servers experienced no issues during the outage. Only mail that our customers sent to Microsoft addresses remained queued with us for a while and was automatically delivered as soon as Microsoft was reachable again.

Read more

• NCSC: In the news: Microsoft Exchange Online outage
• VRT NWS: Microsoft sees improvement after worldwide problems with Outlook, Teams, and Copilot
• ICT Magazine: 89 percent of companies stuck with cloud provider for at least 3 weeks

The WebOké team