Microsoft 365 outage pushes banks and traders back to phones and faxes

First reported 13 Nov, 19:45 UTCSource: Crypto BriefingLast editorial activity 13 Nov, 19:45 UTCWrite a comment ↓

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A worldwide Microsoft 365 outage left millions of people without email and sent bankers, traders and shipping firms back to telephones and faxes, according to one outlet's report. The disruption ran for roughly 12 to 18 hours before Microsoft signalled that conditions were improving.

How the disruption spread

Trouble with Microsoft 365 surfaced around midday Eastern Time on November 12, or 17:00 GMT. Users in at least 74 countries and territories were affected, and Outlook, Teams and Copilot were all hit, while SharePoint, OneDrive and Defender XDR ran into connectivity problems or degraded performance.

The heaviest damage fell on Exchange Online, the service that underpins Outlook email, where mailboxes were either delayed or unreachable. Downdetector logged peak issue reports above 130,000 for Outlook alone. Microsoft has not published a total count of affected users, and it cites more than 430 million people as the estimated global user base of Microsoft 365.

Workarounds in finance and beyond

With email out of reach, telephones, faxes and even Bluetooth file transfers filled the gap. Bankers, traders and shipping firms were among those caught unprepared. Euronext, the European exchange operator, asked listed companies to reach it by phone while it verified the identities of callers, so a single call had to function as both a channel and a security check. Trading desks in Taiwan and Japan relied on faxes to confirm trades.

Airlines, health services and police forces were also affected. Most institutions reported that their core systems kept running, which points to a fault in the communication layer around those systems rather than in the systems themselves.

Recovery and lessons for businesses

By the afternoon of November 13, Microsoft reported signs of stabilisation after rolling out fixes more broadly, and email delivery moved back toward normal levels. The outage lasted roughly 12 to 18 hours in total.

The episode underlines the risks of depending on a single provider, and commentators urge businesses to build robust contingency plans for when core communication tools fail.

Open questions

How many users were ultimately affected by the outage?
What caused the failure, and has Microsoft published a full explanation?

Key facts

The Microsoft 365 disruption began around midday Eastern Time on November 12, which is 17:00 GMT.

The disruption reached users in at least 74 countries and territories.

Mailboxes were delayed or could not be opened at all.

Microsoft reported signs of stabilisation by the afternoon of November 13.

Exchange Online, the backend behind Outlook email, took the hardest hit.