Microsoft 365 Outlook Outage (November 12, 2026): What Happened and What Admins Should Do

On Thursday, November 12, 2026, Outlook stopped working for a large number of Microsoft 365 organizations. The problem is in Exchange Online, and because so much of Microsoft 365 relies on it, it also broke parts of Teams, Copilot, Intune, Purview and the admin center.

Status as of 9:57 PM Vancouver time (04:57 UTC, November 13): not resolved. Microsoft’s status page still shows Service degradation. Earlier traffic changes brought only partial recovery. Microsoft now says it is scaling up virtual machines to add capacity and trying to force a sync of “our recent network change” to machines that are “stuck in a bad state.” I’ll update this post as Microsoft does.

Below is what Microsoft has said so far, what still works, what to do while it’s down, and what to check once it’s fixed.

The short answer

• What’s down: access to Exchange Online mailboxes through Outlook on the web, Outlook desktop, Outlook mobile (Exchange ActiveSync) and apps that use REST. Microsoft says email delivery may be delayed.
• What else is affected: anything that needs Exchange Online, including Teams calendars and meeting scheduling, Copilot’s access to mail, calendar and files, some admin center pages, Intune check-ins, Purview policies and Safe Links checks.
• What still works: Teams calls, meetings, chats and channel messages, and files stored directly in SharePoint.
• Is mail lost? Microsoft says delivery “may be delayed.” It hasn’t said any mail was lost.
• Where to check: status.cloud.microsoft. It’s the public page Microsoft uses when admins can’t get into the admin center, which is the case for some admins today.
• Don’t reset passwords, rebuild Outlook profiles or reinstall Office. Nothing on your side will fix this.

What Microsoft says happened

Reports started around 1 p.m. Eastern (11 a.m. in Vancouver, 10 a.m. on the US West Coast). Downdetector showed about 130,000 reports for Outlook (CNBC).

Microsoft’s explanation has changed during the day, which is normal for an incident still in progress:

• At first, Microsoft said part of its infrastructure was “experiencing elevated load across multiple regions.” It then said a number of servers were “unexpectedly unavailable,” which strained the remaining infrastructure (ABC News).
• Microsoft later said “a process on the affected servers responsible for establishing secure connections becomes overwhelmed, causing the servers to stop processing requests” (ABC7).
• Microsoft paused all deployments, moved traffic off the affected infrastructure and restarted servers. In the afternoon it “validated an alternative service health check method” that brought some servers back (CNBC).
• Around 6 p.m. Eastern, Microsoft said some servers were back and stable so far, but warned that they “can become unresponsive again once they receive traffic” (ABC News).
• In the evening, its status page said a change meant to improve service was “not taking as expected,” and that it was looking at ways “to increase capacity in the face of sustained traffic management imbalances.” Later updates reported partial recovery in some regions, but not yet a lasting one, and mentioned a surge of traffic from Microsoft’s routing services to its backend servers.

Treat all of this as Microsoft’s preliminary explanation. The real root cause comes in the post-incident report, which I cover below.

The consumer side (Outlook.com, OneDrive, Teams for personal accounts) is also listed as degraded on the same status page, as a separate issue.

What’s affected beyond Outlook

Microsoft’s status page says features “that interact with Exchange Online and email services are impacted,” and parts that don’t depend on Exchange keep working. Here’s its list, shortened:

Service	What may not work	What still works
Exchange Online	Mailbox access in Outlook on the web, desktop, mobile and REST apps; delayed delivery
Teams	Calendar, scheduling and invites, creating live or virtual events, creating or deleting private and shared channels, Copilot answers about mail and calendar	Calls, meetings, group chats, channel messages
Copilot	Copilot Chat may not load; no access to work email, calendar or files
SharePoint Online	Features that depend on Exchange	Opening files stored in SharePoint
Admin center	Some pages may not load
Defender for Office 365	Safe Links may not be able to check URLs in Outlook and Teams
Defender XDR	Some portal pages
Intune	Enrollment, check-in and compliance, intermittently
Purview	DLP, sensitivity labels and auto-labeling, audit search, eDiscovery search and export, opening protected content
Microsoft Graph	Requests for mail, calendar and contacts may time out
Planner, To Do, Universal Print	Operations may fail
Power BI and Fabric	Exporting reports with sensitivity labels

The list is long because Exchange Online isn’t only email. Calendars, Copilot’s grounding in your mailbox, label and DLP checks, and many apps built on Microsoft Graph all go through it. When it’s down, they go down with it.

What to do while it’s down

1. Confirm it’s this outage, not your tenant

Check status.cloud.microsoft first. If you can open the admin center, the incident is also under Health > Service health, where you’ll see the incident number for your tenant (How to check Microsoft 365 service health). Microsoft also posts updates on X at @MSFT365Status.

If the symptoms match (Outlook can’t connect, mail not arriving, Teams calendar empty), stop troubleshooting. Help desk time spent on individual mailboxes today is wasted.

2. Don’t make changes that won’t help

• Don’t reset passwords or revoke sessions because Outlook asks people to sign in again. That’s a symptom of the outage, not a compromise, unless you have other evidence.
• Don’t rebuild Outlook profiles, reinstall Office or remove the account from phones. Classic Outlook for Windows in Cached Exchange Mode keeps a local copy of mail and calendar, so people can usually still read what had already synced. Removing the account deletes that copy, and messages written now generally wait in the Outbox until Outlook reconnects.
• Don’t switch off security policies or change mail flow and DNS to “get mail moving.” You’d be weakening your tenant for a problem you can’t fix from your side.

3. Tell people once, and give them another channel

Send one short message through a channel that works, such as a Teams post or a text: Microsoft has an outage, mail is delayed, don’t open tickets about it, use Teams chat or the phone for anything urgent, and we’ll post when it’s back.

For customers and suppliers waiting on an email, a phone call is faster than hoping the message arrives.

4. Be careful with links

Microsoft says Safe Links may not be able to check URLs in Outlook and Teams right now, so a link people click today may not be checked. Outages also attract phishing that pretends to fix them (“Sign in here to restore your mailbox”). Remind staff that the fix is on Microsoft’s side and nobody needs to sign in anywhere to get their mail back. I wrote about how one phishing email turned into a full account takeover in MFA Didn’t Stop the Attack.

What to check once it’s fixed

When Microsoft marks the incident as restored:

• Delayed mail. Check that mail is arriving and that people’s sent messages left the Outbox. Microsoft has said delivery may be delayed, not that mail was lost. If something important still hasn’t arrived by the next day, ask the sender whether they got a non-delivery report.
• Automations. Power Automate flows that use the Outlook or Office 365 connectors, scheduled reports and anything else that reads mail or calendars through Microsoft Graph may have failed during the outage. Check run histories and resubmit what matters.
• Intune. Check-ins and compliance were intermittently affected. Before acting on devices that show as non-compliant, check whether it happened during the outage.
• Purview. DLP, auto-labeling, audit searches and eDiscovery exports were affected. Re-run searches and exports that failed. If your compliance team relies on DLP or labels for regulated data, tell them this window existed.
• Meetings and calendars. Invites and changes sent during the outage may not have gone through. Ask people to check the meetings they scheduled today and tomorrow.
• The post-incident report. For incidents with broad impact, Microsoft says it delivers a preliminary post-incident review (PIR) in Service health within 48 hours of resolution, and a final one within five business days (Service health and continuity). That’s where the actual root cause will be. Keep it if you report on SLAs or need to explain the outage to management.

What this outage shows

Service health alerts that go to the tenant’s own mailbox can’t warn you

You can have Service health email you about incidents: in the admin center, go to Health > Service health > Customize > Email and pick the services you care about. Each admin can add up to two addresses (Microsoft Learn). If both addresses are mailboxes in the same tenant, an Exchange outage stops the alert too. Make one of them an address outside your Microsoft 365 tenant.

Email is how you get back into other accounts

Tonight I tried to sign in to a web service and couldn’t, because it sent its verification code to a mailbox I couldn’t open. Password resets and sign-in codes for many outside services depend on that mailbox. For the services your business can’t do without (your domain registrar, your bank, your other cloud providers), make sure at least one admin has a recovery method that doesn’t depend on Microsoft 365, like an authenticator app or a phone number.

Know what depends on Exchange Online

Most organizations know Outlook depends on Exchange. Fewer know that their Teams meeting scheduling, Copilot answers, DLP policies, device compliance and internal apps built on Microsoft Graph do too. A short list of what stops when Exchange stops, who owns each piece and how you’ll tell staff, turns a day like today from guesswork into a routine.

That’s the kind of map I build when I review a Microsoft 365 tenant: what runs on what, who gets notified and what you check afterwards. It doesn’t stop Microsoft’s outages, but it means you already know what to do when one happens.

Checklist

During an outage:

• Check status.cloud.microsoft and Service health before troubleshooting.
• Tell staff once, through a channel that works, and route urgent work to Teams calls or the phone.
• Don’t reset passwords, rebuild profiles, reinstall Office or weaken security policies.
• Warn people about links and phishing that pretends to fix the outage.

After it’s fixed:

• Check delayed mail, Outboxes and meetings scheduled during the outage.
• Resubmit failed flows, reports and Graph jobs.
• Review Intune compliance changes and failed Purview searches from the outage window.
• Read the post-incident report when Microsoft publishes it.

Before the next one:

• Send Service health alerts to at least one address outside your tenant.
• Make sure the key admins can recover critical accounts without Microsoft 365 email.
• Write down what depends on Exchange Online and how you’ll tell people.