Microsoft 365 went down around the world on Thursday 12 November 2026, and Outlook users are still feeling it on Friday. Email stopped arriving, mailboxes would not open, and several apps that depend on email broke with it.
The good news is that this was not a cyberattack, your delayed mail is not lost, and recovery was already well under way by Friday morning. Here is what broke, what still works, and what you should do while things settle.
What happened
The outage began at about 16:17 UTC on Thursday 12 November — 11:17 a.m. Eastern time. Microsoft tracks the problem under two incident numbers: EX1550543 for Exchange Online, the service that stores work and school mailboxes, and MO1550821 for the wider Microsoft 365 impact.
At the peak, more than 120,000 Outlook problem reports were logged on Downdetector, and the outage was reported in 74 countries. Outlook stopped opening mailboxes whether people used the desktop app, Outlook on the web, or a phone mail app.
Microsoft has said there is no sign of malicious activity. Its updates describe servers that became unexpectedly unavailable and then buckled under the load, and it has promised a full post-incident report, including the root cause, once service is fully restored.
What is down, and what still works
Exchange Online is the heart of the problem, so anything built on email is affected. Outlook mailboxes may not open, and mail sent during the outage can arrive hours late.
Several other Microsoft 365 features lean on Exchange, so they broke too: calendars, meeting scheduling and invites, Copilot, Planner, To Do, Intune and Purview are all affected to some degree.
But it is not true that everything is down. Core Teams calls, meetings and chats mostly still work. That is the detail many early reports got wrong — Teams is not down, but the parts of Teams that touch calendars and email are.
As of Friday morning in the US, Microsoft said it was seeing clear improvements in service availability and that email queues were significantly reduced and approaching normal levels. It had not declared the incident resolved, and some users may still see intermittent problems or delayed mail while recovery continues.
What to do while email is delayed
First, do not panic about missing mail. Microsoft extended how long Exchange Online keeps trying to deliver delayed email to 48 hours, so messages sent during the outage should still arrive instead of bouncing back.
Try another way in before you assume your account is broken. If the desktop app will not load your mailbox, try Outlook on the web, or the Outlook app on your phone. One route can work while another is still stuck.
Use Teams for urgent messages. Since core Teams chat and calls mostly kept working, it is the fastest way to reach colleagues while email catches up. While email is delayed, many teams also fall back on chat apps — our WhatsApp login guide covers getting into WhatsApp on phone, web and PC if you need a backup channel.
Do not keep resending the same email. Each resend adds another message to the queue and can create duplicates once delivery catches up. Send it once, and check your Sent folder later to confirm it went.
Do not delete and re-add your Outlook account. That is a common reflex when a mailbox will not load, but during an outage it can make things worse — the account may fail to set up again while the service is still recovering.
If you manage Microsoft 365 for a company, check Service health in the Microsoft 365 admin centre and follow incidents EX1550543 and MO1550821 for the official updates. Everyone else can follow the same updates on Microsoft’s public status page and the Microsoft 365 Status account on X.
Will Microsoft pay you back?
Microsoft has service-level agreements for business customers, and a long outage can qualify for service credits. The exact terms depend on your plan, so check the service credits section of your Microsoft 365 agreement or ask your admin. Consumer and free accounts do not get the same credits.
How to check if it is Microsoft, or just you
Before you reset anything, check whether the problem is on Microsoft’s side. Open Microsoft’s public status page on your phone or another network and look for the Exchange Online incident. If it is listed as a service degradation, the fault is Microsoft’s and the fix is to wait.
If the status page shows everything is healthy but your mailbox still will not load, try signing out and back in, restart the Outlook app, and check your internet connection. A single user with a stuck mailbox while everyone else is back is usually a local problem, not the outage.
Frequently asked questions
Is Microsoft 365 still down?
As of Friday morning, 13 November 2026, recovery was well under way and email queues were close to normal, but Microsoft had not declared the incident resolved. Check Microsoft’s public status page for the latest update before you assume it is over.
Is the Microsoft 365 outage a cyberattack?
No. Microsoft has said there is no indication the outage is the result of malicious or cyber activity. The company will publish a full post-incident report with the root cause once service is restored.
Will my delayed emails arrive?
Yes, in most cases. Microsoft extended the email timeout window to 48 hours so delayed messages keep being delivered instead of bouncing. Mail may arrive late, but it should arrive.
Does Teams still work during the outage?
Mostly, yes. Core Teams calls, meetings and chats kept working. What breaks is the part of Teams that depends on email — calendars, scheduling and meeting invites.
