Microsoft's email service went down for users in dozens of countries late on Thursday night India time. Microsoft says some of its servers became unavailable without warning. Below: what we know, a full timeline in IST, and what IT teams should do now.
Zirakpur, 13 November 2026. Status last checked 6:30 am IST. We will update this page as Microsoft posts new information.
Key facts
What: A large Microsoft 365 outage. Exchange Online mailboxes (Outlook on the web, desktop and mobile) were hit, along with Teams, SharePoint Online, Microsoft Copilot and Microsoft Defender XDR.
When: From about 11:24 pm IST on Thursday 12 November (17:54 UTC). It peaked around 11:30 pm IST.
Scale: Close to 130,000 Outlook reports on Downdetector in the US alone. Problems were reported in 74 countries and territories.
Cause (so far): Microsoft says some servers went offline unexpectedly, and the rest were overloaded by the extra load. It has not yet named a root cause.
Status at 6:30 am IST, 13 Nov: Partly recovered, and recovery is uneven. No all-clear yet.
Incident IDs: EX1550543 (Exchange Online) and MO1550821 (wider Microsoft 365). Both are in the Microsoft 365 admin center.
What happened
On Thursday 12 November 2026, Microsoft Outlook went down for a very large number of users. Many people could not open their mailboxes, send or receive email, or connect to other Microsoft 365 apps.
The Microsoft 365 Status account first said it was investigating Exchange Online mailbox problems "through multiple connection methods in the Americas". About 13 minutes later it said users in any region might be affected. AFP, using Downdetector data, reported problems in 74 countries and territories, including parts of Europe, Asia and Africa.
In the US, close to 130,000 users reported Outlook problems on Downdetector shortly after 1 pm Eastern time (11:30 pm IST). There were also thousands of complaints about Teams and Copilot. Five hours later about 37,000 people were still reporting problems.
For Indian businesses, the outage hit in the late night and early morning. Office-hours teams mostly missed it. Night shifts, global capability centres and anyone serving US clients felt it as it happened.
Timeline (IST)
All times below are India Standard Time. They are converted from the UTC times of Microsoft's own status posts.
What Microsoft has said about the cause
Microsoft has not announced a root cause yet. Its explanation changed during the night, and the changes matter.
First explanation: "elevated load." Early on, Microsoft said part of its infrastructure was under elevated load in several regions. Many people read that as a traffic surge.
Correction: missing servers, not extra traffic. About an hour later, Microsoft said the load came from a number of servers going offline unexpectedly. The remaining servers then had to carry their work.
Suspected trigger: health checks. Microsoft found no recent change that lined up with the start of the problem. It said the failed health checks might come from one component that processes server health. A different health-check method brought some servers back.
Recovery that doesn't hold. In its latest update, Microsoft said restored servers could fail again once they took traffic. It is rebuilding some servers on an older configuration and limiting traffic in some places while it works out what started the failure.
None of Microsoft's updates mention a cyberattack. They don't rule one out either. We suggest not repeating claims about an attack until Microsoft publishes its post-incident review.
Our reading: A system's health checks deciding that healthy servers are unhealthy is a well-known way for large systems to fail. Load balancers take servers out of rotation, the remaining servers overload and fail their own checks, and the problem spreads. That would explain why "restart the servers" did not fix things quickly. This is our interpretation of Microsoft's public updates, not Microsoft's confirmed root cause.
Which services were affected
According to Microsoft's MO1550821 advisory, as relayed on Microsoft Q&A, users might not be able to connect to:
Exchange Online: Outlook on the web, Outlook desktop (classic and new), Outlook mobile
Microsoft Teams
SharePoint Online
Microsoft Copilot
Microsoft Defender XDR
Microsoft has not said that every customer was affected. Your tenant's Service Health page shows whether the incident applies to you.
Is Outlook down for me right now? How to check
Before you change anything on your own systems, find out whether the problem is Microsoft's or yours:
Microsoft 365 admin center → Health → Service health. Search for EX1550543 and MO1550821. Admins see more detail here than the public pages show.
The public status page (status.cloud.microsoft) and the Microsoft 365 Status account on X. Use these if the admin center won't load.
Test from a different network and device. If Outlook on the web fails on mobile data as well as on the office network, the problem is almost certainly Microsoft's.
What to do if you are still affected
For everyday users
Don't reset your password, delete your Outlook profile or reinstall Outlook. None of these fixes a problem on Microsoft's side, and they can cause new ones once the service is back.
Classic Outlook in Cached Exchange Mode keeps a local copy of your mail. You can still read and search what you have already downloaded. Messages you write wait in the Outbox and send once the connection returns.
Incoming email is very unlikely to be lost. Under the standard email protocol (SMTP), a sending server that can't deliver a message keeps trying. RFC 5321 recommends retrying for at least four to five days, which is far longer than this outage. Expect a burst of delayed mail as service recovers.
For anything urgent, use another channel. Phone or a messaging app is fine for now. Then follow up by email for the record.
For IT and security teams
Tell staff early, on a channel that doesn't depend on Microsoft 365. SMS, WhatsApp or a status page. If your incident communications run on Teams and Outlook, they went down too.
Freeze non-urgent tenant changes until Microsoft confirms recovery. It's hard to tell an outage symptom from a problem you introduced.
Expect phishing. Big outages bring fake "verify your mailbox" or "restore your account" emails. Warn users that IT will never ask for their password to fix an outage.
Write down your impact. Note start and end times, affected users and business processes. You will need these for a service-credit claim under your Microsoft agreement and for your own post-incident review.
Why this matters for Indian businesses
This is not a one-off. Microsoft 365 had a widespread outage on 22–23 January 2026 (tracked as MO1221364) that lasted about ten hours. On 31 August Microsoft blamed another incident on a problem with a core authentication configuration. Each was a different failure with the same result: mail, chat and documents unavailable together.
The lesson is not "leave Microsoft 365". For most organisations it is still more reliable than running Exchange themselves. The lesson is that putting everything on one platform puts everything at risk at once. When mail, chat, files, identity and even security monitoring (Defender XDR) all depend on the same cloud, one incident takes out all of them, including the tools you would use to manage the incident.
From our work on cloud and DevOps resilience, these are the practical steps that hold up in real outages:
Keep an out-of-band communication plan that does not depend on your main productivity suite. Have a contact list, a backup messaging group and a simple status page.
Map which business processes depend on Microsoft 365, and give each a manual fallback. Think of approvals, customer support inboxes, invoice dispatch and OTP or notification emails sent through Exchange.
Don't send customer-facing email through your staff mailboxes. Send transactional email (receipts, alerts, OTPs) through a separate email delivery service so it keeps working when Outlook doesn't.
Set your own recovery targets. Microsoft's financially backed SLA for Microsoft 365 is 99.9% monthly uptime. That allows about 43 minutes of downtime a month, and a single night like this one can use up several months of it. Service credits pay you back for downtime but don't keep your work going. Our guide to multi-region database replication explains how to set recovery time and recovery point targets.
Design your own systems to fail safely. If your applications depend on Microsoft Graph or Exchange APIs, use timeouts, retries with backoff and circuit breakers so a Microsoft outage doesn't take your application down with it. We cover these patterns in Building Fault-Tolerant Microservices.
If you want a second opinion on how your organisation would get through the next outage like this, our DevOps and Cloud Solutions teams run resilience reviews that cover exactly this.
What happens next
Microsoft usually publishes a Post-Incident Review (PIR) in the admin center within a few days of a major incident. It should confirm the root cause and what Microsoft will change. We will update this article when the incident is resolved and when the PIR is out.
Frequently asked questions
Is Outlook down today? As of 6:30 am IST on 13 November 2026, Outlook and Microsoft 365 were partly recovered, but Microsoft had not declared the incident resolved. Check status.cloud.microsoft or incident EX1550543 in your admin center for the latest.
What caused the Microsoft Outlook outage? Microsoft says some of its servers went offline unexpectedly, and the remaining servers were overloaded. It suspects a component that processes server health checks. It has not yet confirmed a root cause.
Was the Outlook outage a cyberattack? Microsoft has not said so. None of its status updates mention an attack, and none rule it out. Wait for the post-incident review.
Will I lose emails sent to me during the outage? Very unlikely. Sending mail servers keep retrying for days when a recipient's server is unavailable, so most delayed messages should arrive after recovery.
Which Microsoft services were affected? Exchange Online (Outlook on the web, desktop and mobile), Teams, SharePoint Online, Microsoft Copilot and Microsoft Defender XDR, according to advisory MO1550821.
What time did the Outlook outage start in India? Microsoft's first status post came at about 11:24 pm IST on Thursday 12 November 2026, and reports peaked around 11:30 pm IST.
