Microsoft 365 Outage, Nov 2026: What UK Businesses Can Do

Microsoft 365 has been disrupted since Thursday afternoon, 12 November 2026. Exchange Online and Outlook are the hardest hit, and services that depend on them, including Teams calendars and Copilot, are failing or slow. As of midday Friday 13 November, Microsoft reports phased recovery with improving mailbox access and email processing, but some users still see intermittent problems.

GMT and UTC are the same in November, so every time in this article is UK time. Last updated: 12:00 GMT, 13 November 2026. For anything after that, use the live Microsoft 365 status page, which shows Microsoft's official advisories for Microsoft 365 business, personal and Azure in one place, checked every five minutes, with the time of each update. It is independent and not affiliated with Microsoft.

Which Microsoft 365 services are affected?

Email is the core problem. Exchange Online, the cloud mailbox service behind Outlook, is where the fault sits, so anything that reads or writes to a mailbox is affected with it. Microsoft's advisory names the following services and symptoms; we have left out anything Microsoft has not confirmed itself.

Microsoft also lists its consumer products as degraded, so staff checking personal Microsoft mail may see problems too. Azure shows no issues at the time of writing. Microsoft has not published figures for how many users or organisations are affected, so we do not estimate them. The BBC reports schools, GPs and businesses among those hit in the UK.

What is still working

Core Teams messaging, calls and meetings; standard Teams channels; and files opened directly from SharePoint or OneDrive. Tell staff these are the tools to rely on today.

Microsoft 365 outage timeline in UK time

The problem began on Thursday afternoon as an Exchange Online incident and was widened to a Microsoft 365-wide advisory the same evening. By midday Friday, Microsoft was reporting phased recovery, not full restoration.

• Thursday 12 November, about 16:17: Exchange Online incident EX1550543 opened.
• Thursday 12 November, about 18:26: Microsoft 365 advisory MO1550821 opened as impact spread to Exchange-dependent services.
• Overnight into Friday: Microsoft reported that recovery actions "have progressed in phases across affected Microsoft 365 infrastructure", with telemetry and customer reports showing "incremental improvement in several workloads", while "service health remains variable and capacity has not yet fully returned to baseline".
• Friday 13 November, morning: Microsoft reported recovery actions completed across portions of its Asia Pacific infrastructure, traffic gradually restored, and improvements in mailbox access and delayed email processing, with intermittent issues continuing for some users.
• Current state at 12:00: Microsoft's next update was due by 12:00 GMT on 13 November. An overdue update deadline is not a recovery estimate.

For updates after 12:00, check the live status page rather than this article.

What has Microsoft said about the cause?

Microsoft has not confirmed a root cause. Its service health advisory states: "At this time, we have no evidence of malicious activity associated with this incident. We will continue to treat this with urgency until full mitigation, and we will share a full Post-Incident Report with root cause and defense-in-depth actions after mitigation is complete."

Two terms matter here. Mitigation is the fix that stops the impact on users. A Post-Incident Report (PIR) is Microsoft's written account of what went wrong and what it is changing, usually published in the admin centre Service health area for affected tenants after the incident closes.

On the current work, Microsoft says: "Our focus is now on extending these recovery actions across affected infrastructure in other regions, while continuing stabilization efforts and adding supporting capacity to improve service consistency." It adds that "reducing email queues and backlogs remains a priority, and the extended 48-hour email timeout window remains in place to help protect delayed messages as delivery catches up."

If staff ask whether this was a cyber attack, Microsoft's statement is the only authoritative source. It currently says no evidence of malicious activity. That is a present finding, not the final one, and commentary on social media about what broke is speculation until the PIR appears.

How do I check whether my organisation is affected by the Microsoft 365 outage?

Sign in to the Microsoft 365 admin centre at admin.microsoft.com, open Health in the left menu, then Service health, then the Incidents tab, and look for MO1550821 and EX1550543. EX1550543 is the Exchange Online incident; MO1550821 is the wider Microsoft 365 advisory. Your tenant's Service health view says whether your organisation is listed as affected. Only a Global admin or Service support admin can see it, so many small firms will need to ask their IT provider.

If the admin centre itself will not load, Microsoft posts the same information on its public service status page, which it maintains precisely because administrators may be unable to reach the admin centre during an incident.

The live Microsoft 365 status page gathers Microsoft's official advisories for Microsoft 365 business, consumer products and Azure in one place. Its collector checks every five minutes, each update carries its timestamp, and data is flagged as stale after 15 minutes without a successful collection. It does not measure uptime, estimate affected-user totals or invent restoration times.

While you are in the admin centre, switch on Service health email alerts for at least two people, so the next incident is pushed to you rather than discovered by refreshing Outlook.

What to do while Outlook and Teams are down

Agree one backup way to reach staff and customers, stop repeating fixes that cannot help, tell customers plainly that email may be delayed, and keep a simple log.

Backup channel. Core Teams is working, so keep internal work there. For customers, use the office phone and voicemail, and name one person who decides when to switch channels.

What not to do. Password resets, reinstalling apps, rebooting and changing mail routing do not address a Microsoft-side fault, and some create new problems. Never disable security settings or multi-factor authentication to work around it.

Scams. Outages are a common phishing lure. Microsoft will not phone your staff about this incident or ask them to sign in again through a link.

Customers. Put a short, factual note on your website banner, social accounts and voicemail: email may be delayed, here is the phone number, please resend anything urgent once service is restored. Do not promise a time.

Delayed email. Microsoft's 48-hour timeout means queued messages should still arrive. Resending the same email several times creates duplicates once the backlog clears.

Prioritise. Pick the two or three time-sensitive jobs (invoices, deliveries, appointment confirmations) and handle those by phone or SMS first.

Keep a simple outage log

Start a spreadsheet or notebook now with these columns: time (UK), service, symptom, who was affected, business impact, and the source of the status update. You will need it for customer conversations, any service credit request and the review afterwards. Reconstructing it later is unreliable.

What to review once Microsoft 365 service is restored

Once Microsoft confirms mitigation, check that delayed mail and calendar changes have caught up, read the Post-Incident Report, and use your log to fix the gaps that hurt most.

On the day: confirm mail flow in both directions, look in Outbox and Drafts for stuck messages, review calendar invites sent or changed during the window, and check shared mailboxes and any automated emails (invoices, booking confirmations) that queue through Exchange.

Then review the log. Which processes had no fallback? Who did not know the backup channel? Which customers were affected? Write the agreed backup plan on one page and share it with staff. Confirm at least two people receive Service health alerts and bookmark the live status page.

On service credits: Microsoft 365 business subscriptions carry a service level agreement that provides credits, not cash compensation, and credits do not cover lost business. Requests go through Microsoft support or your reseller within a set period and need the dates, times and incident numbers from your log (EX1550543 from about 16:17 GMT on 12 November 2026; MO1550821 from about 18:26 GMT). Check the current terms rather than assuming an amount.

When the Post-Incident Report appears in Service health, read it and decide whether anything in it changes how far you rely on Exchange-dependent workflows.

Reducing dependence on a single supplier

Unity Bridge Solutions helps UK businesses with software and AI automation, including building processes that keep running when one supplier has a bad day. If this outage exposed a gap you want closed, you can contact us.