UK disruption remains ongoing
For affected UK businesses, the disruption remains ongoing. The Microsoft update summarised below reports recovery progress in parts of Asia Pacific; it does not confirm that UK services have recovered. Clients should continue to use their agreed alternative communication methods where email is unavailable.
Microsoft reports further progress towards recovery, with recovery actions completed across portions of the affected infrastructure in the Asia Pacific region. Traffic is being restored gradually, with improvements in mailbox access and delayed email processing.
The incident is not yet fully resolved. Some users may continue to experience intermittent problems. Microsoft is extending recovery actions to affected infrastructure in other regions while continuing stabilisation work and adding capacity.
Reducing email queues and backlogs remains a priority. Microsoft says its extended 48 hour email timeout window remains in place to help protect delayed messages while delivery catches up. This is additional time for delivery attempts, not a guarantee that every message has already arrived.
Microsoft says it currently has no evidence of malicious activity associated with this incident. It plans to publish a full incident report covering the root cause and measures to improve resilience after mitigation is complete.
Which services may be affected?
Impact can differ between organisations and users. Some services may work normally while another person in the same business or school sees errors, delays or intermittent access.
Exchange Online is at the centre of the disruption. Users may be unable to open their mailbox through Outlook on the web, Outlook desktop, mobile devices or applications using Microsoft programming interfaces. Email delivery may also be delayed.
- Outlook and Exchange Online mailbox access
- Delayed email delivery
- Parts of the Microsoft 365 admin centre
- Recent files shown in Microsoft 365 applications
- Microsoft 365 Education features including Assignments and Reading Progress
- Microsoft 365 Copilot responses that need email, calendar or file information
- Some Microsoft Defender for Office 365 and Defender XDR features
- Some Microsoft Graph, Intune, Planner, Power Apps and Purview functions
- Microsoft To Do and Universal Print
- Teams calendar, meeting scheduling and other features that depend on Exchange Online
What is still working?
Microsoft says most core Microsoft Teams functions, including joining calls and meetings, group chats and standard channel messages, are not affected. Calendar related functions and features that depend on Exchange Online may still fail.
Files stored directly in SharePoint Online remain accessible, although external sharing and features which depend on Exchange Online may be affected.
If a service is working, avoid signing out, clearing application data or reinstalling the application while the incident continues. Microsoft specifically advises that users already signed into Power Apps or Field Service may avoid further impact by remaining signed in.
What staff should do
Use an approved alternative method such as a telephone call or Teams chat if an urgent message cannot wait for email. Remember that a message sitting in an Outbox or Drafts folder may be delivered later when service recovers.
Do not repeatedly resend the same email unless it is essential. Several copies may arrive once delayed delivery resumes.
If a Microsoft Safe Links protected address fails to open, do not disable security protection or copy an unfamiliar destination into the browser. Confirm the destination through a trusted route or wait for the service to recover.
- Do not reset passwords simply because Outlook will not connect.
- Do not remove and recreate Outlook profiles unless IT has confirmed a separate local problem.
- Do not reinstall Microsoft applications during the outage.
- Keep a note of urgent messages that may need to be resent or confirmed later.
- Use approved alternative contact details for urgent operational, safeguarding or customer matters.
- Report any problem that continues after Microsoft confirms full recovery.
Advice for Microsoft 365 administrators
Check Health and then Service health in the Microsoft 365 admin centre for information specific to your tenant. The principal incident is MO1550821. Exchange Online impact is also tracked under EX1550543.
Do not make broad configuration changes in an attempt to fix a Microsoft platform incident. Record any local symptoms and affected users so that remaining problems can be investigated after the service is stable.
Microsoft recommends using its public service status page and the Microsoft 365 Status account when the admin centre or Service health page cannot be reached.
How Bury I.T. Support is responding
Bury I.T. Support Ltd is monitoring Microsoft's service updates. We will update this article when Microsoft confirms that the incident has been fully resolved.
Clients do not need to report every individual Outlook error while the Microsoft incident remains active. Please contact us if the problem is affecting a critical business or safeguarding process, if you need help with an approved alternative way of working, or if a service still fails after Microsoft declares recovery.
At the time this article was published, Microsoft had reported improving stability but had not announced full restoration.
Official sources and further reading
These primary sources were checked when this article was last reviewed.