On Thursday, November 12, Microsoft 365 had a large outage that mostly hit Outlook and Exchange Online mailboxes in the Americas. People could not open their mailboxes, send or receive mail, or get messages delivered on time. Teams and Copilot had problems too. If your office lost email for part of the day, the problem was on Microsoft’s side, and there was nothing wrong with your computers or your network.
Key takeaways
- Exchange Online (Outlook email) was the main service affected. Teams and Copilot also had trouble.
- Downdetector passed 130,000 Outlook reports in the US in the early afternoon Eastern time (Euronews).
- Microsoft said part of its infrastructure was under higher than normal load. It paused deployments and redistributed Outlook connection traffic to restore service.
- Mail that could not be delivered during the outage is normally queued and retried by the sending server, so most of it should show up late rather than not at all.
What happened?
Microsoft said on its Microsoft 365 Status account that users were “experiencing issues accessing Exchange Online mailboxes through multiple connection methods in the Americas,” and later warned the issue could affect connectivity “for users in any region” (KPRC/AP). Microsoft later said it had found a pattern where affected servers were becoming intermittently unavailable, which put more strain on the rest of the infrastructure. It redistributed Outlook traffic to balance the load and warned this could cause some latency while the change was in effect (Yahoo News). A separate Teams problem in North America that started that morning was resolved around noon Eastern.
News reports later in the day said service was coming back for most people. Microsoft has not published a full root cause yet. We will update this post when its post-incident report is out.
This is the second big Microsoft 365 outage this year. On January 22 an infrastructure problem in North America took Microsoft 365 down for close to ten hours (The Register).
Is my data safe?
Nothing reported so far points to a security incident. This was an availability problem: the service was slow or unreachable. Your mailbox data stays in Microsoft’s data centers, and an outage does not mean it was lost or exposed.
One caution. Big outages bring phishing with them. Over the next few days, expect fake “Microsoft service restored, sign in to recover your messages” emails. Microsoft will not email you a link asking you to sign in again because of an outage. If you get one, report it to us and delete it.
What should we check now that service is back?
- Look at your Sent Items and Outbox for anything that sat unsent, and resend what matters.
- Ask clients or vendors who were expecting something time-sensitive from you whether it arrived.
- If Outlook still won’t connect, close and reopen it, or try Outlook on the web at outlook.office.com to see whether the problem is the app or the service.
- Avoid running repair tools, rebuilding profiles, or resetting passwords during an outage. None of those fix a problem on Microsoft’s side, and they can create new ones.
How do we keep working through the next one?
You can’t stop a Microsoft outage, but you can decide ahead of time what your team does during one:
- Write down a backup way to reach staff and key clients, like a phone tree, a text group, or a second chat tool, so you are not relying on the service that is down.
- Know where to check status. The Service health page in your Microsoft 365 admin center and the Microsoft 365 Status account on X are where Microsoft posts updates first.
- Keep a short list of who to call and what can wait. Most email can wait an hour. A closing, a payroll run, or a court filing may not.
- Back up Microsoft 365. Microsoft keeps the service running, but it does not promise you point-in-time recovery of your own mail, OneDrive and SharePoint data. A separate backup covers that. Our managed IT services include it.
Frequently asked questions
Was the November 12 Microsoft outage a cyberattack?
Microsoft has not said so. Its explanation so far is higher than normal load on part of its infrastructure, with some servers becoming intermittently unavailable. We’ll update this when Microsoft publishes its root cause.
Will I lose emails that were sent to me during the outage?
Usually not. Sending mail servers queue messages and retry for a period of time, so most mail arrives late instead of not at all. If something important is still missing a day later, ask the sender to resend.
How do I know if Microsoft 365 is down or if it’s just us?
Check the Service health page in the Microsoft 365 admin center, or the Microsoft 365 Status account on X. If Microsoft lists an active incident for your service, the problem is on their end.
Want a plan for the next outage?
If this outage stalled your team, we can help you set up a simple outage plan and a Microsoft 365 backup so the next one costs you less time. Book a free 15-minute review or call (617) 322-5155.
— Boston Managed IT
