Outlook down: what is happening and how a business prepares for an email outage

Outlook has been down since Thursday 12 November and on Friday morning the problem is still not fixed. In many countries Microsoft 365 email will not open, will not send or arrives late. Microsoft says a large number of servers became unavailable without warning and the rest were overloaded. The company says it is not aware of any malicious activity behind the fault. For a business that runs on Microsoft 365 there are four things to do now: leave the configuration alone, move urgent communication to another channel, watch for suspicious messages and write down the times of the outage.

Updated at 10:00 Italian time (9:00 UTC) on Friday 13 November 2026. The outage is still ongoing and details may change.

What happened to Outlook?

The fault is in Exchange Online, the Microsoft 365 service that runs email for companies, firms and public bodies. Microsoft has opened two incidents. The first, EX1550543, covers email and has an official start time of 17:17 Italian time (16:17 UTC) on Thursday. The second, MO1550821, covers the other Microsoft 365 services that depend on email.

People at work felt it about an hour later. On Downdetector, the site where users report faults, reports about Outlook passed 130,000 shortly after 19:00 Italian time. Within about an hour they had come from 74 countries and territories. These are voluntary reports. Microsoft has not said how many mailboxes were affected.

At first Microsoft spoke of the Americas, then of users in any region. Reports from Italy ranged from over one thousand to over two thousand, according to the news outlets that read the Downdetector data, and rose again on Friday morning as offices reopened. The heaviest effects were reported elsewhere. In the United States several public offices warned citizens of slow replies. In Australia schools, courts and federal offices had problems. In Japan, eight hours ahead of Italy, several ministries were without email for most of Friday’s working day.

What is down and what still works?

Microsoft says the features that talk to Exchange Online are affected, while those that do not depend on it keep working.

• Email. Access to the mailbox can fail from Outlook on the web, from the desktop app and from phones. Message delivery can be delayed.
• Calendar and meetings. In Teams the calendar, invitations and meeting scheduling may not work.
• Copilot. The assistant may not respond and may be unable to reach email, calendar and files.
• Administration and security. Some pages of the admin centre may not load. Features of Defender for Office 365, the tool that checks links and attachments in email, are also affected.

According to Microsoft, Teams calls, meetings, chats and channels remain available, and so do files stored in SharePoint.

What does Microsoft say caused it?

The root cause has not been disclosed. Microsoft promises to explain it in a report once the fault is resolved. So far it has described the mechanism. A large number of servers dropped out of service without warning. The load moved to the remaining servers, which were overloaded. Servers brought back into service could stall again as soon as they received traffic.

Between Thursday evening and the night the company rerouted traffic, restarted servers, paused scheduled updates and began rolling back a recent change to the network configuration. More than once it acknowledged that the fixes were not having the expected effect. At 7:57 Italian time on Friday it still spoke of only marginal success. In its 8:29 message it says it is seeing positive results for server stability after a fix applied to part of the infrastructure. In its next update, shortly after 9:00, it says stability is holding where the fix has been applied and that it has started extending it, giving priority to the regions that are in or entering peak business hours. There is still no estimated time for recovery.

Is it a cyber attack?

Not as far as Microsoft knows. In its official messages the company says it is not aware of any malicious activity behind the incident. That wording does not settle the question, because the root cause has yet to be explained. For business continuity it changes little. A supplier fault stops work as much as an attack does and has to be planned for in the same way.

What should a business do right now?

1. Check the official source. Service status is published at status.cloud.microsoft. Administrators can also find it on the Service health page of the admin centre, where the incident appears under the codes EX1550543 and MO1550821.
2. Leave the configuration alone. The fault is in Microsoft’s servers. Changing passwords, removing and re-adding accounts or reinstalling Outlook fixes nothing and slows the return to normal. The same goes for the mail settings of the domain: changing them during an outage risks adding a second problem.
3. Give everyone the same backup channel. For urgent matters use the phone and, where available, Teams chats and calls, which Microsoft says are working. Anyone waiting for a reply from the company should be told straight away, by phone or by message.
4. Watch for suspicious messages. During the outage the automatic checks on links and attachments may not work either. Some banks in Australia and Singapore have warned customers that fraudsters may pose as technical support and offer to fix the Microsoft problem. Staff need one simple rule: nobody resets a password, gives out codes or lets a stranger connect to their computer because a phone call, an email or a text message asks them to. Anyone who fears they have already given their password to someone should tell the IT manager at once, so that it can be changed.
5. Write down times and affected users. You need them for the credit claim to Microsoft, explained below, and to know afterwards what the outage cost.
6. Do not resend in bulk. Messages written in the Outlook desktop app stay in the Outbox and leave when the connection returns. Duplicates confuse clients.

What should you check when email comes back?

Microsoft speaks of delayed delivery, not lost messages. It has given no guarantee, though, and no time for clearing the backlog. When service returns, three checks are worth making.

• The Outbox of everyone who worked during the outage, to see whether anything is stuck.
• Orders, quotes and deadlines that travelled by email between Thursday evening and Friday. For the important ones a confirmation call costs less than a misunderstanding.
• Messages received during the hours of the fault, to be handled with more care than usual because some automatic checks may not have been working.

How do you prepare for the next outage?

This is not the first long outage of the year. In January a Microsoft 365 fault that also hit email lasted almost ten hours. Between the end of August and the start of September the problems went on for about three days. A business that relies on a single email provider has to expect a few days like this and decide in advance how it works when they come. Four decisions, taken calmly, are enough.

• An emergency channel agreed in advance. Everyone must know where to meet if email stops and who tells the clients.
• Contacts kept outside email. Numbers and addresses of clients, suppliers and advisers in a list that can be reached even when Microsoft 365 is down.
• A backup mailbox with another provider for senior management and for those who handle external relations, to be used only in emergencies.
• Who decides and who communicates. One name for the decision to switch to the backup plan and a text already written for clients and suppliers.

These are the same questions as in a real cyber incident. A business that has already written them into a plan finds them ready for a supplier fault too.

What does the contract with Microsoft provide?

Microsoft’s contract terms for its online services, in the edition dated 1 November 2026, promise 99.9% monthly availability for email. Below that threshold the customer can claim a credit on the monthly fee.

• Below 99.9% the credit is 25%.
• Below 99% it is 50%.
• Below 95% it is 100%.

In a thirty-day month 0.1% is about 43 minutes. A company with all users down for more than 7 hours and 12 minutes falls below 99%. The calculation is based on the users actually affected and the decision rests with Microsoft.

There are three things to know. The credit does not arrive by itself: it has to be claimed from support, stating times, duration, affected users and the errors seen. For this outage the claim must be filed by 31 December 2026. The credit is the only remedy provided by those terms and does not cover lost revenue or the cost of the stoppage. Anyone who bought licences through a reseller should ask the reseller now how the claim is filed.

In brief

• Outlook has been down since Thursday 12 November. At 10:00 Italian time on Friday 13 the outage is not resolved and Microsoft has given no estimate for recovery.
• The fault is in the Exchange Online servers. Microsoft has not disclosed the root cause and says it is not aware of an attack.
• In the business, leave the configuration alone, use a backup channel, watch for suspicious messages and write down the times.
• During the outage some email security checks may not work either.
• The credit on the fee has to be claimed from Microsoft by 31 December 2026.
• The plan for the next outage should be written as soon as email is back.

Frequently asked questions

Is Outlook down in Italy and Europe too?

Yes. Microsoft speaks of users in any region, and on Friday morning the fault was still ongoing as European offices reopened. Reports from Italy are a small share of the total, though: the news outlets that read the Downdetector data put them at between over one thousand and over two thousand, against more than 130,000 at the worldwide peak.

When will Outlook be back?

Microsoft has not given a time. On Friday morning it said it was seeing positive results for server stability after a fix applied to part of its infrastructure, and that it had started extending the fix. On Thursday night it had warned that recovery may be gradual, as mail apps reconnect.

Were emails sent during the outage lost?

Microsoft speaks of delivery that may be delayed and has so far reported no lost messages. It has given no guarantee, though. For important messages it is worth asking the recipient for confirmation.

Should we move email to another provider?

That is not a decision to take in the middle of an outage. Every provider has its outages. What a business can decide straight away is how it works when email is not there: a backup channel, contacts at hand and clear responsibilities.

Who has to claim the credit from Microsoft?

The customer. The claim is filed with support, with the times of the outage, the affected users and the errors seen, by the end of the month after the one in which the fault occurred.

Preparing a business for the days when an essential service stops, because of an attack or a supplier fault, is the work of Strategic’s Cybersecurity Division. The process is described on the page about incident response.