Outlook and Teams are down for many users right now. Emails are delayed. Messages fail to send. Sign in attempts are bouncing. The disruption started this morning and is still unfolding. I am tracking issues across multiple regions and tenants, with impact that rises and falls by location and product. This is a live incident.
What’s failing and where
Microsoft 365 customers are seeing the same cluster of problems. Outlook cannot sign in or keeps asking for a password. Teams messages hang or show failed to send. Calendar updates take minutes to land, if they land at all. Some users can connect on mobile, then lose access on desktop. Others can read email but cannot send.
Service impact is not uniform. Some organizations have partial access. Others are hard down. Admin portals load for some tenants, then time out. That mix points to issues in shared cloud services, not a local ISP problem.
Microsoft has acknowledged the incident and says an investigation is underway. The company has not shared a root cause yet.
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The technical picture so far
The early symptoms look like identity and transport problems. Sign in loops suggest trouble with token issuance or validation. Intermittent access hints at throttling or a failing back end cluster. Delayed email points to messages piling up in Exchange Online queues. Teams traffic is sensitive to service-to-service calls, so even a small identity blip can ripple across chat and meetings.
At this point, there is no confirmed fault. It could be a change in the authentication layer that rolled out to some regions first. It could be a networking event between services. A DNS error is less likely, because many sessions still resolve endpoints. A global network issue is also less likely, because some users keep partial functionality. The pattern fits a dependency higher in the stack, such as Microsoft’s identity service, Graph APIs, or a control plane used by multiple apps.
Administrators should expect noisy alerts. Health signals can flip between healthy and degraded as retries succeed. Mail will often self heal as queues drain. Teams chats that failed to send may push through later.
How this is hitting users and businesses
Workflows that rely on constant messaging are the first to suffer. Sales teams cannot confirm meetings. Support desks miss tickets that usually route by email. Legal and finance teams lose time as approvals stall. For many companies, Outlook and Teams are the backbone. When they slow, everything slows.
There is also a security angle. Users who cannot sign in may try workarounds. That invites risk. Invoices can get resent from personal accounts. Files get copied to unmanaged devices. These choices make sense in the moment, but they create exposure that outlasts the outage.
Expect phishing to spike during outages. Do not trust unexpected sign in prompts or links that claim to restore access. Use known bookmarks only.
What to do right now
Here is the playbook I recommend while Microsoft works on a fix:
- Check the Microsoft 365 Service Health dashboard from an admin account. Note incident IDs and time windows.
- Try alternate clients. Outlook on the web may load when desktop does not. Mobile apps can also work in a pinch.
- Shift critical conversations to a fallback, such as phone bridges or a secondary chat tool your company already approves.
- Queue email for later. Draft and save. Exchange often delivers once queues clear.
- Communicate with customers and partners. Set clear expectations for delays and offer a backup contact path.
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If conditional access blocks your fallback, add a temporary, time bound exception and log every change. Remove it as soon as services stabilize.
Services showing impact
- Outlook and Exchange Online, sign in errors and delayed mail
- Teams, message failures and meeting join issues
- Admin portals, intermittent loading and error pages
- Some SharePoint and OneDrive actions, slower than normal for some users
What this means for cloud resilience
Incidents like this test the single vendor model. Microsoft 365 is integrated by design. That brings speed and control in normal times. It also means a shared dependency can take multiple tools down at once. The lesson is not to rip and replace. It is to plan layers.
Companies need clear fallback paths. That includes a secondary comms channel, an offline workflow for approvals, and a way to reach customers when email is slow. Identity is the real choke point. When sign in breaks, everything breaks. Investing in staged access policies and break glass accounts pays off on days like this.
Vendors will study the blast radius. Expect fresh promises about isolation, safe rollout rings, and faster rollback tools. Those are welcome. Still, customer playbooks matter just as much. Outages are not rare anymore. They are a cost of scale. The teams that recover fastest are the ones that rehearse.
The bottom line
Microsoft is working to restore Outlook, Teams, and other Microsoft 365 services. The impact is broad but uneven. Many users can do some work, then hit a wall. Treat today like a continuity drill. Keep people informed, protect identity, and use simple backups. When Microsoft clears the fault, mail will flow and chats will catch up. Your plan for the next incident should be stronger than it was this morning.
