Microsoft's email servers started failing on Thursday, 12 November 2026, at about 1:25 PM Eastern (18:25 UTC). At 10:01 UTC on Friday, more than 15 hours later, Microsoft's public status page still listed Microsoft 365 for business as "Service degradation". The latest update said recovery was progressing in phases, but capacity had not returned to baseline, and it gave no time for full recovery.
If your business email runs on Outlook or Exchange Online, you have felt it already. What fewer people know is that business plans come with a contractual uptime commitment, and falling below it earns a credit on the bill. Microsoft does not apply that credit by itself. You have to ask for it.
Which services went down
Microsoft traces the incident to Exchange Online. Users could not open their mailboxes in Outlook on the web, in the desktop app or on mobile, and incoming mail was delayed. Anything that depends on Exchange broke with it: calendar features inside Teams, meeting invites, Copilot's access to email and files, external sharing from SharePoint, and some admin center pages. Teams calls and meetings themselves mostly kept working.
Microsoft says it has no evidence of malicious activity and has promised a full post-incident report once the problem is fixed. So far it has described servers becoming unexpectedly unavailable and putting strain on the rest of the system.
Mail sent to you during the outage
The detail that matters most to a small business sits near the end of Microsoft's notice. To protect delayed messages, Microsoft extended the email timeout window to 48 hours. Mail sent to you during the outage should arrive late rather than bounce or vanish.
It is still worth checking. A customer who says they paid, a supplier who sent an invoice, an order from your website: if any of these has not shown up by Sunday, ask for it again or confirm by phone. The same goes the other way. If you sent a digital receipt by email from a Microsoft mailbox on Thursday evening or Friday, make sure the customer actually got it.
How much credit you can claim
Microsoft's Service Level Agreement for Online Services commits Exchange Online to 99.9% monthly uptime. Uptime is counted in user-minutes: the minutes each user in your organization could not work, out of all the minutes in the month. Falling below the threshold earns a percentage of the monthly fee for the affected service:
| Monthly uptime | Cumulative downtime in a 30-day month | Service credit |
|---|---|---|
| Below 99.9% | More than about 43 minutes | 25% |
| Below 99% | More than about 7.2 hours | 50% |
| Below 95% | More than about 36 hours | 100% |
A business whose staff had no email for the whole incident has already passed the 7.2-hour mark. One whose mail came back after an hour or two is probably in the first tier. The calculation is per organization, so there is no single answer.
Filing the claim
If you bought your subscription directly from Microsoft, open a support request in the Microsoft 365 admin center and quote the incident numbers: MO1550821 for the broader incident and EX1550543 for Exchange Online. If you bought through a reseller or a Cloud Solution Provider, the claim goes through them.
The request has to arrive within one month after the end of the billing month in which the outage happened. For a subscription that bills at the start of each month, a claim for November has to go in by the end of December.
Before you file, write down when email stopped working for each user and when it came back. Screenshots of error messages with a visible time will help support the request.
Personal accounts, meaning Outlook.com and Microsoft 365 Personal or Family, are not covered by this agreement. Credits apply to business and enterprise plans.
For Israeli businesses the timing is awkward: the outage began on a Thursday evening and ran through Friday, when many offices are closed, so the first full working day to check missing mail and gather evidence is Sunday 15 November.