On a Friday in mid-November, the ordinary rhythm of working life stalled again for many people who found their inboxes closed to them, as an outage that began the day before continued to ripple through Microsoft's cloud services. The failure has reached Outlook on the web and desktop, the connections that sync mobile mail, and a wider web of tools built on Exchange, from calendars to Copilot. Microsoft's earlier repairs did not hold, and the company is now searching for other ways to add capacity while it works through traffic imbalances, with no timeline for full recovery yet offered. It is a
Microsoft Outlook Outage Persists as Company Struggles to Restore Exchange Online and Wider Microsoft 365 Services
Microsoft's changes were "not taking as expected."
Mark
Start with the basics. What actually broke?
Mimi
Access to Exchange Online mailboxes. Outlook on the web, desktop, Exchange ActiveSync and REST connections were all affected, and email may be delayed. It started Thursday, November 12, and was still going Friday.
Mark
And it spread beyond email?
Mimi
Anything leaning on Exchange. Teams calendars and meeting scheduling, Copilot features that read work email, To Do, parts of Defender. But Teams messaging and meetings mostly work, and SharePoint files are still reachable.
Luke
I'd be careful with that list. Microsoft also named Planner, Purview, Fabric and Graph as potentially affected. That's not confirmed impact.
Mimi
Right, and even for the confirmed ones, it varies by location, account and feature.
Mark
What's the most telling line in Microsoft's update?
Mimi
That its changes to improve availability were "not taking as expected." The first fix didn't work, so it's now looking at other ways to add capacity while traffic management stays imbalanced.
Luke
Notice what that doesn't say. No root cause is given beyond traffic imbalance, and no timeline.
Mark
So can anyone say when it ends?
Luke
No. The reporting says plainly there's no confirmed restoration time. Anything else would be a guess.
Mimi
What readers can do is watch incidents EX1550543 and MO1550821 and use other channels for urgent messages.
Luke
Also, the claim of thousands of affected users is reported, not a figure from Microsoft.
Il Polso
- Outlook mailboxes stayed locked out for a second day, with users unable to reach email through web, desktop, and mobile sync routes.
- Sending and receiving messages slowed or stalled, leaving businesses and organisations scrambling for other ways to communicate.
- Microsoft's earlier fixes failed to take hold, and engineers are now hunting for alternative ways to add infrastructure capacity.
- Calendars, meeting scheduling, and Copilot's email-linked features are among the hardest hit, while the company still has no restoration timeline.
On a Friday in mid-November, the ordinary rhythm of working life stalled again for many people who found their inboxes closed to them, as an outage that began the day before continued to ripple through Microsoft's cloud services. The failure has reached Outlook on the web and desktop, the connections that sync mobile mail, and a wider web of tools built on Exchange, from calendars to Copilot. Microsoft's earlier repairs did not hold, and the company is now searching for other ways to add capacity while it works through traffic imbalances, with no timeline for full recovery yet offered. It is a reminder of how much of modern work rests on infrastructure most people never see until it falters.
On Friday, November 13, people trying to open their Outlook inboxes were facing the same wall they had hit the day before. The trouble began on Thursday, and by morning Microsoft's service health updates confirmed that Outlook and other Microsoft 365 services were still affected. Thousands of users reported being unable to get into their work accounts.
Microsoft is tracking the email problem under incident EX1550543. Users may be shut out of their Exchange Online mailboxes through Outlook on the web, the desktop app, and mobile sync connections, and messages may arrive or leave late. The company's latest update offered little comfort. Changes meant to improve availability were "not taking as expected," and engineers are now looking for other ways to add capacity while they wrestle with persistent imbalances in traffic management.
The disruption spreads well past Outlook. Teams messaging and meetings mostly work, but calendars and meeting scheduling may fail. Copilot can be slow to respond, and To Do and parts of Defender may misbehave. SharePoint files remain reachable, though features tied to email and calendars may not.
No full restoration timeline has been announced. For those wondering whether the problem lies on their side, Microsoft's service health page and the Microsoft 365 Admin Center are the places to check, along with Downdetector for signs of wider trouble. Switching devices or browsers is unlikely to help while the infrastructure itself is strained. For urgent work, other channels are the safer bet until email settles, and the next signal to watch is whether Microsoft's new capacity measures succeed where the first attempts did not.
On Friday, November 13, people trying to open their inboxes in Outlook were still running into the same wall they had hit a day earlier. The disruption began on Thursday, November 12, and by Friday morning Microsoft's own service health updates showed that Outlook and other Microsoft 365 services were still affected.
Microsoft is tracking the email problem under incident reference EX1550543. According to the company, users may be unable to connect to their Exchange Online mailboxes through several routes: Outlook on the web, the Outlook desktop application, Exchange ActiveSync and REST-based connections. Sending and receiving email may also be delayed. Thousands of users reported trouble getting into their work accounts, which has raised concern among businesses and organisations that rely on Microsoft's cloud services.
The latest update from Microsoft is not reassuring. The company said it had been monitoring changes made to improve service availability and found they were "not taking as expected." It is now looking at alternative ways to increase infrastructure capacity, while dealing with persistent imbalances in traffic management that continue to affect availability. In other words, the work still centres on stabilising the infrastructure rather than on a confirmed path to full restoration.
The outage reaches well beyond Outlook. Services that depend on Exchange Online are affected in different ways. In Microsoft Teams, core messaging and online meetings remain largely functional, but calendar activities, meeting scheduling and some chat creation features may fail. Copilot may be slow to load Chat or return responses, and features that need access to work email, calendars and files may be hit. Microsoft To Do may not load properly or may fail on certain operations.
SharePoint Online is a mixed picture: features that rely on Exchange Online may have problems, but files stored directly in SharePoint remain accessible. In Microsoft Defender, Safe Links may have verification problems, and some pages of the Defender portal may be hard to reach. In Microsoft 365 applications, some users may not be able to see recently used files.
Microsoft has also flagged possible problems with Planner, Purview, Fabric, Graph and other enterprise services. The distinction matters: these are listed as potentially affected, and the real impact will vary with a user's location, account and the specific feature in use.
As for when it ends, Microsoft has announced no confirmed timeline for complete restoration of Outlook and the other affected services. Until the traffic management issues are resolved and the infrastructure stabilises, users may see intermittent or persistent disruption.
For those trying to work out whether the problem is on their end, the practical guidance is to check Microsoft's official service health page, or the Service Health section of the Microsoft 365 Admin Center for business and enterprise users. Incident EX1550543 covers Exchange Online mailbox connectivity, and incident MO1550821 covers the wider Microsoft 365 disruption. Downdetector shows whether others are reporting similar trouble. Switching devices or browsers may not help while the underlying infrastructure is affected, so for important work communication, other channels are the safer choice until email settles. The next thing to watch is whether Microsoft's alternative capacity measures succeed where the first round did not.
Citazioni salienti
Changes made to improve service availability were "not taking as expected," and Microsoft is exploring alternative ways to increase infrastructure capacity.— Microsoft, service health update
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