Microsoft 365 Outage: What UK Businesses Should Do Now
Outlook, Exchange Online and connected Microsoft 365 services have experienced widespread disruption. Here's what businesses should do during the incident and how to prepare for the next cloud service failure.
Check your tenant's service health, confirm which business processes are affected and use an agreed alternative for urgent communications. Prioritise critical work, avoid weakening security to get around the outage and keep a record of decisions and disruption. Microsoft's recovery work was still ongoing at 09:05 GMT on the 13th of November.
Microsoft began investigating a broad Microsoft 365 outage on the 12th of November, with Exchange Online at the centre of the reported disruption, affecting mailbox access through Outlook and creating knock-on problems for Microsoft 365 features that depend on email and calendar services.
Teams calendar and scheduling functions, Copilot, and several connected services were also among the affected areas, although Microsoft said most core Teams meetings, calls and messaging remained available (seriously, Teams' resilience has to be commended at this point. It just will not die).
For businesses, the immediate priority is to confirm the impact in their own tenant, move urgent communication to an agreed alternative channel, protect critical customer and operational processes, and avoid risky workarounds.
Microsoft said on Friday morning that it hadn't found any indication of malicious activity behind the incident, and the underlying cause still hadn't been confirmed at the time of drafting this blog.
This article reflects the position on the morning of the 13th of November 2026. Microsoft 365 service status can change quickly, so administrators should check the Microsoft 365 admin centre and the Microsoft service health page for the latest information.
What happened in the Microsoft 365 outage?
Microsoft tracked the wider incident as MO1550821 and the Exchange Online issue as EX1550543.
The disruption began on Thursday and continued into Friday, with users in multiple regions reporting difficulty opening mailboxes, sending or receiving email, and using Exchange Online features.
Microsoft said affected infrastructure was experiencing elevated load and that some servers had failed automated health checks.
Recovery work didn't immediately behave as expected when traffic returned, which is why service could appear to improve for some users before becoming unreliable again.
By 9am on Friday, Microsoft reported early signs of stabilisation after patching an upstream authentication and routing component, but capacity hadn't returned to normal. Engineers were reintroducing traffic in stages and continuing to investigate the cause.
The impact reached beyond a broken Outlook screen, as features across Microsoft 365 could fail when they depended on Exchange Online or email. A service might still open even if a calendar, notification, search, approval, or integration within it fails.
The incident also reached beyond Microsoft applications. AP reported disruption to companies and public bodies, while connectors used by other technology platforms were affected because they relied on Microsoft 365.
One supplier problem can therefore travel through several tools before it reaches the user.
What should UK businesses do now?
A major outage creates pressure to fix something locally, even when the failure sits with the provider.
That can lead to repeated reconfiguration, duplicate messages, and relaxed security controls in the hope of getting people moving, but as with any type of incident, a calmer response is usually more effective.
Confirm the scope in your own environment
Check Service health in the Microsoft 365 admin centre and look for MO1550821 and EX1550543. Record which users, locations and business processes are affected. Test the functions that matter, rather than assuming every part of Microsoft 365 is either fully working or fully down.
Use an agreed communication fallback
Move urgent internal updates to a channel that doesn't depend on the affected Microsoft service, which might be a separate and secure messaging platform, SMS or phone. Staff should know where the official update will appear; otherwise several unofficial conversations quickly become their own incident.
Prioritise business-critical work
Identify deadlines, customer requests, payment approvals, support queues and operational handovers that rely on email or calendars. Give those workflows an owner and a temporary route. Not every delayed message needs emergency treatment, but a time-sensitive customer or supplier instruction might.
Don't trade security for access
Avoid disabling MFA, changing access policies or encouraging staff to use personal email without approval. Outages also create convincing phishing opportunities, including fake service alerts and urgent requests to sign in elsewhere. Use Microsoft and your IT provider as the source of truth, and verify unusual instructions through a second channel.
Keep a timeline
Note when the impact began, what failed, decisions made, workarounds used and when service returned. This will help with customer communication, supplier review and the post-incident discussion. Memory becomes surprisingly optimistic once everyone can open Outlook again.
What the outage reveals about cloud resilience
Microsoft 365 is deeply embedded in everyday work. Email, calendars, files, meetings, approvals, customer communication and security tooling often sit in the same ecosystem.
That integration is useful, but it can also hide how many processes share the same dependency.
And here's the thing we all seem to forget at times like this. Cloud services can fail, just as on-premises systems do. They're not immune to issues, so don't think it's a complete disaster that's come out of the blue and panic (although it is incredibly frustrating, I get it).
Equally, most businesses don't need to duplicate the whole of Microsoft 365. Maintaining a second platform can add cost and complexity without creating a fallback people can actually use.
The priority is to identify concentrated dependencies and plan around the processes that can't simply wait.
Map the work that depends on Microsoft 365
Start with business processes rather than an application list. Which customer responses arrive only by email? Which approvals rely on Teams notifications? Which service desk, CRM or finance workflows read a shared mailbox? Which senior contacts exist only in Exchange?
A dependency map should show what stops, who notices and how long the business can tolerate the interruption.
Keep continuity information outside the affected platform
An outage plan stored only in SharePoint is awkward when this exact scenario happens, and the problem affects access to Microsoft 365.
Keep a controlled copy of essential contacts, escalation routes and first-response actions somewhere the incident can't take down with it.
The document should be short enough to use under pressure and reviewed often enough that the phone numbers still belong to the right people.
Separate backup from availability
A Microsoft 365 backup protects recoverable data. It doesn't usually make Outlook or Teams available during a live Microsoft service outage.
Backup, disaster recovery and business continuity solve related but different problems. Organisations should know what each service will and won't provide before an incident.
Test the fallback in ordinary time
A secondary communication channel only helps if people can access it and recognise it as legitimate.
Run a short exercise: assume email and Teams are unavailable for two hours, then test how leadership updates staff, how customer-facing teams receive instructions and how urgent approvals are recorded.
The awkward moments are the useful findings.
Clarify responsibility with your IT partner
During a provider outage, an IT partner can't repair Microsoft infrastructure, and they're in the same boat as you are.
Yet, businesses still need a clear owner to monitor service health, communicate with users, manage workarounds, check recovery, and turn the incident into practical improvements.
That support matters most when the update is more useful than another person saying Outlook is still down.
Microsoft 365 outage FAQs
Is Microsoft 365 still down?
Microsoft still classified the incident as service degradation at 09:05 GMT on Friday the 13th of November 2026. Recovery was under way, but capacity hadn't returned to normal and impact varied by user, feature and region. This is a historical status update. Check the Microsoft service health page and the Service health view in your Microsoft 365 admin centre for the latest position. See also the incident updates referenced in this article.
Was the Microsoft outage caused by a cyber attack?
Microsoft said on Friday morning that it wasn't aware of malicious activity causing the incident. The company hadn't published a final root cause at the time of drafting. Businesses should avoid repeating an unconfirmed explanation until Microsoft issues its post-incident report. Read the incident updates.
Which Microsoft 365 services were affected?
Access to Exchange Online and Outlook was central to the incident. Teams calendar and scheduling functions, Copilot and features in several other Microsoft 365 services could fail when they depended on Exchange Online or email. Microsoft said most core Teams calls, meetings, group chats and channel messages weren't affected. Tenant-specific impact may differ. See the incident updates.
Will a Microsoft 365 backup keep email working?
Usually not. Backup services help recover data after deletion, corruption or another loss event. They don't normally provide a live replacement for Microsoft email during a Microsoft 365 outage. Your provider should explain the precise recovery and availability options in your setup.
Should businesses move away from Microsoft 365?
One outage isn't, by itself, a reason to replace a major productivity platform. It does justify reviewing dependencies, continuity arrangements and the business impact of downtime. The response should be proportionate to the processes at risk and the length of interruption the organisation can tolerate.
What to do after Microsoft 365 recovers
Once service stabilises, check that queued email, calendar updates, workflows and integrations have caught up.
Look for duplicates and confirm that any temporary process has been closed cleanly. Then hold a short review while the details are still fresh, encompassing:
- Which services and business processes failed first
- How quickly staff received a clear update
- Whether the alternative communication route worked
- Which decisions or approvals became difficult to evidence
- What should change in the continuity plan, monitoring or supplier arrangement
Microsoft will restore the platform in time, but the more valuable outcome for your business is knowing what to do before the next provider issue begins.
If this Microsoft 365 outage exposed gaps in communication, continuity, or ownership, Fifosys can help you review dependencies, test the fallback plan, and turn the findings into practical improvements.
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