Global Microsoft 365 outage: what happened and what it means for you

Since yesterday afternoon, Microsoft has been dealing with a major global outage affecting Microsoft 365. Organisations around the world have been impacted, including some of our clients.

What happened

The problem started at around 17:15 (CET) on Thursday 12 November, with users in the Americas unable to access Exchange Online mailboxes. By early evening, Microsoft confirmed it could affect Microsoft 365 users in any region.

Which services are affected

According to Microsoft, users may be unable to connect to:

• Exchange Online (Outlook, on desktop and on the web)
• Microsoft Teams
• SharePoint Online and OneDrive
• Microsoft 365 Copilot
• Microsoft Defender XDR

What caused it

Microsoft hasn't published a final root cause yet. Its updates point to an infrastructure problem rather than a security incident. Servers across several regions came under very high load, and a core process on those servers became overwhelmed, so they failed health checks and dropped out of service. Microsoft has said it isn't aware of any malicious activity behind the outage, and it has committed to publishing a full root cause report once service is restored.

Where things stand

Microsoft has moved traffic across its global infrastructure, restarted affected servers and added extra capacity. It has seen partial recovery in some regions, but that recovery hasn't held yet, and it hasn't given an estimated time for full restoration.

For ongoing updates, visit our status page at bmitstatus.com. IT administrators can also follow incidents MO1550821 and EX1550543 in the Microsoft 365 admin centre, or Microsoft's public status page at status.cloud.microsoft.

What this means for you

If your organisation is affected:

• Don't reset passwords, reinstall Office or rebuild Outlook profiles. The problem is on Microsoft's side, so these steps won't fix it and may cause extra work once service returns.
• Outlook may still show your existing mail. If your desktop app keeps a local copy, you can usually still read past emails even when it can't connect.
• Incoming email isn't normally lost. Sending mail servers usually keep retrying, so most messages should arrive once service recovers, though some may be delayed.
• Use other channels for anything urgent, such as phone, while Teams and Outlook are unreliable.
• Watch out for phishing. Scammers often use major outages as cover, with fake "re-verify your account" or "restore your mailbox" emails. Microsoft won't ask you to sign in through an email link to fix this.

Our services

BMIT's own datacentre, network and hosted services are not affected by this incident. Our teams are supporting affected clients. For updates, visit bmitstatus.com, or contact our Service Desk on 2258 8200.