Microsoft’s Email Fix Isn’t Finished, And Messages Stuck Past 48 Hours Will Bounce
Microsoft says it has fixed the cause of its day-long email outage, but some customers are still waiting, and any message still stuck when a 48-hour delivery window runs out goes back to its sender.
Key Takeaways
- Microsoft blamed a problem from an earlier network capacity upgrade that surfaced after a recent network change
- It said the outage was a technical issue, not a cyberattack or anything to do with AI agents
- Delayed emails get up to 48 hours to be delivered before senders get a bounce message
- Microsoft is still restoring service to remaining customers and will publish a full report
In its latest update, at 18:05 UTC on Friday, Microsoft said it was “seeing broad recovery and stability across our services.” It added: “We have addressed the underlying issue and continue to restore service to remaining customers and regions.”
The trouble began on Thursday at 17:54 UTC, when Microsoft first reported that users could not reach their Exchange Online mailboxes.
Also Read: Microsoft Email Meltdown Drags Into Day Two As Fixes Fail And Police Tell Britons To Phone Instead
What Caused It
“The incident was introduced by an issue during an earlier network capacity upgrade that surfaced following a recent network change,” Microsoft said. It called it “a technical issue not related to cyber or AI / agents.”
Microsoft said it brought services back gradually and checked stability at each stage, which took longer. “We are deeply sorry for the disruption this incident has caused our customers and partners,” it said.
What Happens If It Is Not Fixed
For anyone still affected, the first risk is email. Mail servers keep retrying messages they cannot deliver, but only for a set time, and Microsoft stretched that window to 48 hours during the outage. Under Exchange rules, a message still undelivered when the window runs out is sent back to its sender as a nondelivery report, better known as a bounce.
That means emails stuck since the worst of the outage on Thursday could start bouncing over the weekend if delivery does not catch up. Senders would then have to send them again.
The second risk is work slowing down. On Friday morning, Police Scotland and Dorset Police told the public their online forms were down and asked people to call 101 or 999, and schools asked parents to phone in absences. Organizations still waiting for a full fix would stay on those workarounds.
The third is money. Microsoft’s service level agreement promises 99.9% monthly uptime for its online services, which allows about 43 minutes of downtime in a 30-day month, and business customers can claim service credits when it falls short. A day-long outage goes far beyond that.
What Comes Next
Microsoft said its teams are reviewing what happened “and how we can prevent similar issues going forward,” and that it will publish a full post-incident report once the review is complete.
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