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Microsoft Exchange Online Flags Customers Legitimate Email as Phishing

Cybersecuritynews •Guru Baran • February 9, 2026

Microsoft Exchange Online is experiencing a service degradation that incorrectly flags legitimate customer emails as phishing, quarantining them and disrupting communications. The issue, identified as EX1227432, started on February 5, 2026, at 10:31 AM EST and remains ongoing. Microsoft classifies this as an incident affecting Exchange Online, with some users unable to send or receive […]

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Microsoft Exchange Online Misclassifies Legitimate Emails as Phishing Microsoft is investigating an incident affecting Exchange Online that began on February 5, 2026, where legitimate emails are being incorrectly flagged as phishing and quarantined. This issue has disrupted business communications for many organizations using Microsoft 365. The problem is linked to a newly implemented URL detection rule. 13 sources 32

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Microsoft Exchange Online Flags Customers Legitimate Email as Phishing

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