Updated 14 November 2026: Microsoft's admin center now lists both incidents as “Service restored”. We will add what Microsoft's post-incident report says once it is published.
At least 28 hours passed between Microsoft's listed start of the incident and its 2:00 PM UTC update on 13 November, which still reported intermittent issues. For many business customers, Outlook mailboxes, Teams scheduling and a long list of other Microsoft 365 services were affected in that time.
This post covers what Microsoft said, what the outage touched, what is still unknown, and five things we would change in how a business prepares. For the update-by-update record as it happened, see our live outage post.
What happened, in four milestones
These are the four moments that mattered. Every update Microsoft posted is in our live outage post. Times are EST and UTC.
Time (EST / UTC) | What Microsoft said or showed |
Fri 13 Nov, 11:15 PM EST / Sat 14 Nov, 4:15 AM UTC | The admin center lists both incidents as “Service restored” (last updated at this time). The public status page shows all products operational. A post-incident report will follow. |
Fri 13 Nov, 9:00 AM EST / 2:00 PM UTC | Email queues are significantly reduced and approaching normal levels. Some users may still see intermittent access issues or delayed email. Microsoft has added mitigation and is restoring the remaining infrastructure. |
Fri 13 Nov, 2:29 AM EST / 7:29 AM UTC | Positive stability results after a patch to an upstream authentication and routing configuration component. Microsoft is extending the patch to servers in active regions. |
Thu 12 Nov, 5:05 AM EST / 10:05 AM UTC | The start time Microsoft's admin center lists for both incidents. |
What the outage touched
Microsoft listed features that depend on Exchange Online as affected. Parts of those services that do not use Exchange Online kept working.
- Outlook and Exchange Online: mailbox access could fail on Outlook on the web, Outlook desktop, Exchange ActiveSync and REST connections. Email delivery could be delayed.
- Microsoft Teams: calendar scheduling, invites, meeting edits and live events failed. Calls, meetings and chat mostly worked.
- Copilot, Planner and To Do: Copilot Chat could fail to load or reach email, calendar and files. Planner and To Do had reliability problems.
- Office apps and SharePoint: the recently used files list could be empty, and sharing files with people outside the organization could fail. Files stored directly in SharePoint still opened.
- Admin and security tools: the admin center, Defender, Purview, Intune and Microsoft Graph were listed, along with Power Apps mobile sign-in and Power BI and Fabric exports of items with sensitivity labels.
One detail matters for any business. Microsoft said administrators might be unable to open the admin center, so it posted the incident on its public status page instead.
What we know about the cause, and what we do not
Microsoft has said it patched an upstream authentication and routing configuration component, added capacity and adjusted traffic. It has also said it has no evidence of malicious activity. It has not yet published a root cause.
Microsoft has said a full post-incident report, with root cause and actions to strengthen defenses, will follow once mitigation is complete. Until it does, we will not guess. We will update this post when the report is out.
Five lessons for your business
These are our suggestions, not Microsoft guidance.
- Know which processes send email through Microsoft 365. Invoices, purchase approvals, order confirmations and ERP notifications often leave through a Microsoft 365 mailbox. List them now, so the next outage does not start with “what else was that sending?”
- Do not rely on the thing that is down to tell you it is down. Microsoft said admins might not reach the admin center, so it used its public status page. Keep that page, and a way to reach your IT contact, outside your own tenant.
- Agree a second channel for urgent messages. Phone and SMS sit outside Microsoft 365, and Microsoft said Teams calls, meetings and chat mostly worked while mailboxes did not. Decide in advance who uses which channel, and for what.
- Expect delays and duplicates, and check before you resend. Delayed messages can arrive hours later, and resending creates duplicates. Once service is back, check Sent Items and ask your admin to run a message trace for anything important.
- Build the fallback before you need it. A manual path for orders and invoices, and an automatic alert when business emails stop going out, turn an outage into an inconvenience. Our n8n workflow automation work covers the alerting side.
If Outlook still will not send for you, work through our guide to Outlook not sending emails.
A checklist for this week
List every system that sends email through Microsoft 365: ERP, invoicing, approvals and automations.
Check Sent Items and those systems' outgoing mail logs for anything that failed or stayed queued on 12 and 13 November.
Agree a second channel for urgent messages, and write down who uses it.
Save the Microsoft 365 status page and your IT contact's number where staff can reach them without email.
Set a reminder to read Microsoft's post-incident report when it is published.
When your business systems depend on email
Many ERP and automation tools send invoices, approvals and order emails through a Microsoft 365 mailbox. When that mailbox is unreachable, the tool may fail quietly, and no one notices until a customer asks. The review in this post's checklist is where to start.
If you would like help working out what your systems send and how to make it more resilient, talk to a Versich consultant. You can also read about our NetSuite Managed Services, our full range of services, or our n8n workflow automation work.
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