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By Rodrigo Santos Andrade
Why the Microsoft 365 outage is different and why it takes so long to restore email services
visibility comment0 event November 13, 2026 timer 16:45
When one email service goes down, others don’t stop trying to send emails to users of the affected service. The result is snarled traffic that takes time to clear up.
Microsoft was a source of frustration for computer users when it stopped working on Nov. 12, 2026. AP Photo/Michel EulerThe Microsoft services outage that began on Nov. 12, 2026, is not like other internet outages. The failure affected the Microsoft 365 suite of productivity services, including the video conferencing and collaboration platform Teams, AI assistant Copilot and, significantly, the Outlook email service.
Microsoft reported on Nov. 13 that the company is “continuing to see improvements in service availability” but that “some users may still experience intermittent access issues or delayed email delivery.”
Despite decades of predictions about its decline, email remains a central pillar of how organizations function. Password resets, invoices, legal notices and cybersecurity incident response coordination all depend on it. The Microsoft 365 outage affected businesses, governments and schools around the world.
When most people think about cloud outages, they picture a broken website or a stalled app. When the service going down includes email, however, the mechanics of the failure and how to recover from it are different from those of almost every other cloud service.
Unlike modern web apps or authentication gatekeepers, email wasn’t designed to fail fast, meaning to immediately halt when a problem arises.
Old architecture
When a typical cloud service breaks, it acts like a closed door. If an authentication provider or a cloud application goes down, users are immediately locked out and see an error message. Access stops. When people cannot get into the system, they are not actively generating new work or adding heavy processing loads to the broken servers. Once engineers fix the underlying bug and unlock the door, traffic can resume and the service often recovers fairly quickly.
Email does not have a closed door. It is built on an older, decentralized “store-and-forward” architecture designed to never lose a message, even when the destination is unreachable.
Because email is a network of thousands of independent systems, an outage at one major provider does not stop users on other platforms from hitting “send.” During major email disruptions like the one that hit Microsoft, millions of outside users on Gmail, corporate servers or other platforms could still compose and send emails to affected accounts without seeing an immediate error message.
From the sender’s perspective, everything works normally. Their email provider accepts the message, attempts to hand it off to the downed provider, realizes the destination isn’t answering, and quietly holds onto the message in an outbound queue to try again later.
Major highway crash
One way to think about email traffic in outages is to imagine a multilane interstate highway where an accident blocks two lanes of traffic. Drivers miles away don’t stop leaving their driveways just because there is a wreck up ahead; they keep entering the highway system. Soon, traffic backs up so severely that metered on-ramps have to stop letting new cars merge onto the interstate. Before long, that gridlock spills backward onto local feeder roads and city streets, choking traffic miles away from the actual crash site.
In this analogy, a downed email provider is the crash. Every other email server around the world is an on-ramp or a feeder road. While the outage lasts, millions of messages continue to pile up in queues across the internet, with unaffected servers repeatedly resending email to see whether traffic is moving yet.
It takes time to get traffic moving after an accident has been cleared.
Pia Bayer/picture alliance via Getty Images
When engineers finally fix the root cause of an email outage, it is the equivalent of tow trucks clearing the wreckage from the highway. The road is technically open again, but traffic does not instantly return to normal speed.
First, the massive backlog of vehicles already stuck on the main highway has to start moving. Only after that congestion clears can the on-ramps start letting queued-up cars merge back in, which in turn slowly relieves the gridlock on the surrounding local roads.
Similarly, when a major email provider comes back online, it is immediately hit with a tidal wave of pent-up messages and retry attempts from every other mail server on the internet. Processing those queues without overwhelming the newly restored servers takes time – typically hours to days.
Long, bumpy road to recovery
Because organizations have largely outsourced their email to a small number of global providers, an outage doesn’t just disrupt one company; it can stall entire sectors at once, cutting off the communication tool teams rely on to coordinate their emergency response.
And for everyday users, this unique architecture explains why email failures feel so drawn out: Even hours after a provider officially announces a problem is fixed, messages can still arrive out of order or trickle in slowly as the digital traffic jam finally clears.
Doug Jacobson does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Tags: Academic Journalism, The Conversation, The Conversation Academic News
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