Key Highlights
- Microsoft is investigating an issue where legitimate emails are flagged as phishing in Exchange Online.
- The problem began on February 5 and continues to affect users as of February 9, 2026.
- The issue is caused by a new URL rule that incorrectly flags some URLs as malicious.
- Microsoft has confirmed the impact but hasn’t disclosed affected regions or customer count.
So, you might think this is new, but Microsoft is currently dealing with an ongoing issue in its Exchange Online service. The problem? Legitimate emails are being flagged as phishing and quarantined. Yes, you read that right—emails that don’t deserve to be locked up are getting the bird’s eye treatment.
What’s the Deal?
Microsoft first acknowledged the bug on February 5 when it issued a service alert. The company stated, “Some users’ legitimate email messages are being marked as phish and quarantined in Exchange Online.” This is no small potatoes; it’s a serious snafu that’s impacting user productivity.
Why This Matters
You might wonder: how can a URL rule go so wrong? Well, Microsoft has explained. “We’ve determined that the URLs associated with these email messages are incorrectly marked as phish and quarantined in Exchange Online due to ever-evolving criteria aimed at identifying suspicious email messages.” It’s like trying to catch a shadow—a moving target.
How Did We Get Here?
The issue is caused by an updated URL rule that’s meant to identify more sophisticated spam and phishing emails. But apparently, it’s too clever for its own good. “An updated URL rule intending to identify more sophisticated spam and phishing email messages is incorrectly quarantining legitimate email messages in Exchange Online, resulting in impact,” Microsoft added.
The Impact
While Microsoft hasn’t provided the number of affected customers or regions, it has classified this as an incident involving noticeable user impact. Until the issue is resolved, users might start seeing previously flagged messages in their inboxes. Microsoft’s response? “We’re reviewing the release of quarantined messages for affected users and working on confirming legitimate URLs are unblocked.”
History of Woes
Mozilla, if you’re reading this, you know what I mean. This isn’t a first for Microsoft in email security issues. Over the last few years, similar incidents have happened.
In March, Exchange Online mistakenly quarantined some users’ emails as spam. Then, in May, another machine learning model incorrectly flagged Gmail accounts as spam. And just last September, an anti-spam service bug blocked URLs and quarantined emails from both Exchange Online and Microsoft Teams.
The Future of IT
It’s a reminder that even with all the tech wizardry in the world, things can still go haywire. As we move into this future where IT infrastructure is becoming more automated, these kinds of bugs are just as likely to occur as they were back when we had paper trails.
So next time you get a suspicious email and it gets flagged, don’t be surprised if Microsoft is looking at your legitimate message too. Until they sort it out, keep an eye on your inbox—because what’s supposed to protect us might just need protecting itself.
