A Microsoft 365 outage disrupted Outlook mailbox access and other connected services after users began reporting problems on Nov. 12. Microsoft said connectivity could be affected in any region, and its incident was still marked as a service degradation in the latest update we could read.
In a Microsoft incident update mirrored by the University of Pennsylvania, the company said some users could not reach Exchange Online mailboxes through Outlook on the web, Outlook desktop, Exchange ActiveSync or REST-based connections. Email delivery could also be delayed.
What the Microsoft 365 outage affects
The disruption goes beyond opening an inbox. Microsoft said Teams features that rely on Exchange Online, including calendar, meeting scheduling and some chat creation, could fail. Core Teams messaging and online meetings remained largely functional.
Other services that use Exchange data were also listed, including Microsoft Copilot access to work data, recently used files in Microsoft 365 apps and parts of the Microsoft 365 admin center. Microsoft said files stored directly in SharePoint Online remained accessible.
That distinction matters if one colleague can still join a meeting while another cannot load a calendar. The incident does not mean every feature in every Microsoft 365 app is down.
Microsoft investigates server availability
In its Nov. 13 update at 1:12 a.m. UTC, or 9:12 a.m. Philippine time, Microsoft said a process on the affected servers that sets up secure connections becomes overwhelmed, which makes the servers stop processing requests. The company said it was preparing a configuration change for all affected servers and validating it on a subset first.
Microsoft also said it had begun reverting a recent network configuration change that correlates with the start of the impact. Earlier updates described paused deployments, traffic moved away from affected infrastructure and server restarts. Temporary traffic limits were in place in specific locations while service was restored gradually.
Microsoft has not published a final root cause or a recovery time. Treat the details above as the status at the time of that update.
What users can do
If your Outlook mailbox or Teams calendar is unavailable, check with your organization’s IT team. Administrators can follow incident EX1550543 in the Microsoft 365 admin center, and Microsoft also offers a public service status page.
Do not assume a delayed message was delivered. For anything urgent, use an agreed backup channel and confirm that the other person received it.
Why it matters
Microsoft 365 ties email, calendars and workplace tools together, so one failing service can slow tasks elsewhere. Check Microsoft’s latest incident update for your tenant rather than relying on reports from another region. More tech stories are on our News page.
Frequently asked questions
Is Outlook down?
Microsoft said some users could not access Exchange Online mailboxes through Outlook on the web, desktop apps and other connection methods. Impact varies by user and region.
Is all of Teams down?
No. Microsoft said core Teams messaging and online meetings remained largely functional, while calendar, meeting scheduling and some chat creation that depend on Exchange Online could fail.
Is my region affected?
Microsoft said any region may be affected. Check your organization’s Microsoft 365 admin center or the public service status page for your tenant.
