Microsoft 365 and Outlook outage: what to do and what to check

Information checked just after 4:00pm GMT on Friday 13 November 2026. Microsoft’s Exchange Online (EX1550543) and wider Microsoft 365 (MO1550821) incidents were still open. Recovery was progressing, but full restoration had not been confirmed.

Has Outlook stopped connecting, or will Microsoft 365 not load? Microsoft has confirmed a service incident affecting Exchange Online, the email service behind business Outlook mailboxes, along with other Microsoft 365 services. It began on Thursday 12 November 2026 and was still affecting customers on Friday 13 November. JM Restart can help you confirm whether a problem is part of this incident and check that email has settled properly once service returns.

The fault is within Microsoft’s service. Reinstalling Outlook, rebuilding your email profile or resetting your password will not bring email back sooner.

Latest update: Friday 13 November, just after 4pm

Microsoft is reporting sustained improvement, but this is not yet an all-clear. Its latest wider Microsoft 365 service health update, issued at 3:52pm GMT, says engineers are dealing with remaining problems and checking that recovery is stable. Its latest detailed Exchange Online progress message, at 2:57pm GMT, says some people may still experience intermittent Outlook connections or delayed email.

At 2:01pm GMT, Microsoft reported that delayed email queues had been significantly reduced and were approaching normal levels. It has not confirmed that all queued email has been delivered, that every affected service is fully restored or when complete recovery will happen. Microsoft continues to report no evidence of malicious activity associated with the incident; it has not yet published a final root cause. The next wider Microsoft 365 update was scheduled for 6:00pm GMT.

What is happening

On Thursday 12 November 2026, Microsoft opened incident EX1550543 for Exchange Online. Its record gives a start time of about 4:17pm UK time. The Microsoft 365 Status account first reported mailbox access problems in the Americas at 5:54pm, then said shortly afterwards that connectivity could be affected for users in any region. A second reference, MO1550821, covers other Microsoft 365 services. Both incidents remained active at our check just after 4pm on Friday 13 November.

Microsoft describes the impact as people being unable to connect to their mailboxes and to other services that depend on them. The updates we have reviewed describe a problem reaching the service. Microsoft has said it is not aware of any malicious activity behind the incident, and its updates do not report lost mailbox contents.

Not every organisation is affected. If your email is working normally, there is nothing you need to do.

Service or app	What you may notice
Outlook on a PC or Mac	Outlook shows as disconnected or keeps trying to connect. New email does not arrive and sent messages wait in the Outbox.
Outlook on the web	The mailbox is slow, shows errors or does not load.
Email on phones and tablets	New messages stop arriving and replies do not send.
Teams	Core chat, calls and meetings are reported as largely working. Calendars, meeting scheduling, invitations and changes to meetings may fail. Some live events and channel management tasks may also be affected.
Shared files	Microsoft says direct access to files stored in SharePoint remains functional. Sharing with people outside your organisation, and features that depend on email, may fail.
Other Microsoft 365 apps	Microsoft also lists potential problems with Copilot, Planner, To Do, Intune, Power Apps mobile sign-in, Purview, Microsoft Graph, Universal Print and the Defender portal. You may see problems in some and not others.
Email security features	An earlier Microsoft advisory warned that Safe Links might be unable to verify URLs. The latest advisory instead lists possible delays in some Defender for Office 365 data protection and policy checks. These reports do not mean all email security is disabled. Be extra cautious with unexpected links.
Microsoft 365 admin centre	Administrators may find some pages slow or unavailable. Microsoft points to its public status page as an alternative for checking service availability.

The two incident references cover Microsoft 365 for work and school. Microsoft’s consumer status page has also reported a separate incident affecting personal services, including Outlook.com and OneDrive. If a personal Outlook.com, Hotmail or Live account is misbehaving, check that status page for the current position.

What Microsoft has said so far

These are short summaries of Microsoft’s updates, in the order they were given.

When (UK time)	Microsoft’s update, summarised
Thursday 5:54pm	Investigating mailbox access problems through several connection methods in the Americas. By 6:07pm, users in any region could be affected.
Thursday 6:35pm to 7:20pm	Part of its infrastructure is under heavy load. The cause is servers becoming unexpectedly unavailable, not a rise in traffic. Deployments are paused, traffic is moved and affected servers are restarted.
Thursday 7:45pm to 9pm	Servers are failing automated health checks. An alternative health check method returns a first group to service.
Friday 1am to 2am	Restored servers can become unresponsive again once they receive traffic. A process that sets up secure connections is becoming overloaded, and a recent network configuration change is being rolled back.
Friday 4am to 5am	Partial recovery in some regions is not being sustained. Its own traffic changes caused a surge between internal systems.
Friday 7am to 7:25am	Patching and restarting servers brings marginal success, then positive results for server stability. The work is extended to more regions.
Friday about 9am	The email timeout window is extended to 48 hours to help protect delayed messages.
Friday 9:30am to 10am	Early signs of stabilisation, with recovery progressing in phases. Capacity has not yet returned to normal and service health remains variable.
Friday 11am	Further progress, with recovery actions completed in parts of the Asia Pacific region. Traffic is being gradually restored, and mailbox access and delayed email processing are improving.
Friday about 12:25pm	Recovery progressing across Europe, with Japan more stable and North America improving. Some users may still see intermittent problems. No evidence of malicious activity, and a full report will follow once the incident is mitigated.
Friday about 12:40pm	Encouraging recovery progress, with service availability and email delivery improving across a growing portion of the affected infrastructure. Reducing the email backlog remains a priority and the 48-hour timeout window stays in place.
Friday about 1:35pm	Recovery continuing across North America, Europe and Asia Pacific. The focus is on stabilising servers already recovered, completing the work in the areas still affected and clearing delayed email queues.
Friday 2:01pm	Service availability still improving, with email queues significantly reduced and approaching normal levels. Some users may still see intermittent access problems or delayed email.
Friday 2:57pm	Microsoft reports sustained service improvements. Engineers are checking recovery across different Outlook and mailbox connection methods and investigating remaining intermittent access problems and delayed delivery.
Friday 3:52pm	The wider Microsoft 365 advisory says Microsoft is focused on the remaining disruption and verifying that recovery stays stable. It continues to report no evidence of malicious activity. The next wider update is scheduled for 6pm GMT.

At our latest check, Microsoft had not declared the incident resolved, confirmed a final root cause or given a time for full recovery. The 2:01pm Exchange Online advisory said delayed email queues were approaching normal levels, and the 2:57pm update reported sustained improvements in service availability. The broader 3:52pm advisory concentrated on resolving remaining problems and checking stability. There is still no confirmation that all queued email has been delivered. In practice, Outlook may reconnect and then drop again while services are stabilised; a reconnection is not yet an all-clear. Microsoft’s service health information is the best place to check the current position.

Microsoft has described overloaded processes responsible for secure connections and has investigated configuration and traffic-routing changes. Those are technical findings from its recovery work, not a completed root-cause determination. Microsoft says it has no evidence of malicious activity associated with this incident and will publish a post-incident report after mitigation.

Sources and live checks: See Microsoft’s public service status, the Microsoft 365 admin centre Service health (for administrators) and Microsoft 365 Status. The detailed Exchange Online incident timeline (EX1550543) and Microsoft 365 incident timeline (MO1550821) are third-party reproductions of Microsoft’s service health messages. Availability and affected features may vary between organisations.

Will email sent during the outage be lost?

Microsoft says it is prioritising the backlog of delayed email and has extended its email timeout window to 48 hours to help protect some messages while recovery continues. This may allow more delayed email to be retried and delivered later, but it does not guarantee that every message will arrive. At 2:01pm GMT on Friday Microsoft reported that its email queues had been significantly reduced and were approaching normal levels. It has not confirmed that the backlog is fully cleared.

There are limits. Microsoft has not said that every message is protected. The sender’s own email system decides how long it keeps trying, and some give up sooner. Time-limited messages, such as sign-in codes, may have expired by the time they arrive. If a sender tells you they received a delivery-failure notice, ask them to resend. Avoid asking everyone to resend everything, because delayed copies may still arrive and leave you with duplicates.

What to do while email is unavailable

1. Check Microsoft’s service status page before changing anything. Administrators can also open Health, then Service health, in the Microsoft 365 admin center and look up the two incident references. Microsoft explains how to check service health.
2. Leave Outlook, your account and your device settings as they are.
3. Keep working from what you already have. Outlook on a PC normally keeps a copy of recent email and calendar entries on the device, so you may still be able to read existing messages and find contact details while it is disconnected.
4. Use the telephone or another agreed method for anything urgent. Teams chat and meetings are reported as largely working, but Teams calendars and scheduling are affected, so do not rely on Teams alone.
5. Note anything time-sensitive that you tried to send, such as a quotation, invoice or appointment confirmation, so it can be checked afterwards.

Avoid moving confidential work to personal email accounts as a shortcut. It can create a data protection problem that outlasts the outage.

What not to do

• Do not uninstall or reinstall Outlook or the Microsoft 365 apps.
• Do not delete your Outlook profile, or remove the account from your phone and add it again. Messages waiting to send and recent changes that have not yet synchronised could be lost, and the mailbox will need to download again afterwards.
• Do not reset your password or change your multi-factor authentication (MFA) settings as a fix. MFA is the extra sign-in check, such as an app approval or a code. Microsoft’s updates point to its own servers, not to customer accounts.
• Do not change DNS records, email routing or firewall settings to work around the incident.
• Do not send the same message several times. Queued copies may all be delivered when service returns.

If you are unsure whether your problem is part of the incident, ask before making changes. A short check is quicker than undoing a rebuild that was never needed.

Be cautious of outage-themed scam messages

A widely reported outage gives scammers a convenient story. Be wary of any email, text or call claiming that your mailbox needs to be restored, verified or reactivated because of the incident. This is a precaution, not a report of a specific campaign.

Take extra care with links during this incident. An earlier Microsoft advisory warned that Safe Links, a Defender for Office 365 feature that checks URLs, might not be able to verify some links. Its latest advisory focuses instead on possible delays in certain security policy checks; it has not provided an explicit all-clear for every feature. If you are not expecting a link, do not open it.

Microsoft is repairing its own service. You do not need to follow a link to sign in, share a code or approve a sign-in request you did not start. Open Microsoft 365 the way you normally do. Our phishing, spoofing and email security guide explains the warning signs, and our passwords, MFA and passkeys guide covers sign-in protection.

What to check once service returns

1. Give Outlook time to reconnect and synchronise. If it still shows as disconnected after Microsoft reports recovery, close and reopen it, then restart the device if needed.
2. Look in the Outbox and Drafts folders for anything that did not send. Check Sent Items before sending a message again.
3. Look for delayed incoming email. Messages sent to you during the incident should appear as Microsoft works through its backlog, possibly many at once. If a sender tells you they received a delivery-failure notice, ask them to resend.
4. Review meeting invitations, acceptances and calendar changes made during the incident.
5. Check shared mailboxes, phones and tablets as well as your main computer.
6. Confirm anything time-critical with the customer or supplier directly instead of assuming it arrived.

If email is still not behaving normally several hours after Microsoft marks the incident as resolved, the cause may be local and worth investigating separately.

Planning for the next outage

Cloud email is dependable for most organisations most of the time, but no provider can promise uninterrupted service. A few inexpensive preparations make an outage easier to manage:

• Make sure someone knows where to check Microsoft’s service status and who your Microsoft 365 administrator is.
• Keep key customer, supplier and staff telephone numbers somewhere that does not depend on your mailbox.
• Agree how urgent messages will be handled if email or Teams is unavailable.
• Understand what your backup does. An independent backup of Microsoft 365 data helps you recover information that is deleted or lost. It does not keep email flowing during an outage.

Some organisations add a separate email continuity service. Whether that is proportionate depends on how long you could work without email, so it is worth discussing before buying anything.

How JM Restart can help

We support Microsoft 365 for businesses, including Exchange Online, Outlook, Teams, SharePoint and OneDrive, under an agreed scope. During and after an incident like this, that can include:

• Confirming whether a problem matches Microsoft’s incident or needs separate investigation.
• Checking Outlook, shared mailboxes and mobile devices once service has returned.
• Helping establish whether particular messages were sent or received.
• Reviewing who receives Microsoft’s service health notifications and who can check them.
• Reviewing backup and recovery arrangements for your Microsoft 365 data.
• Planning a proportionate fallback for urgent communication.

We cannot restore a Microsoft service that Microsoft itself is repairing, and neither can any other support provider. What we can do is help you avoid unnecessary changes and pick up cleanly afterwards.

You do not need to buy your licences from JM Restart to ask for help. Read about our cloud and Microsoft 365 support, managed IT services and business backups and disaster recovery.

Call 01473 527430 or email [email protected]. If your email is not working, the telephone is the quickest route. Tell us who is affected, which app or device they are using and what they see. Keep passwords and authentication codes out of your enquiry.