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Microsoft working to fix Exchange Online mailbox quarantine issue
July 22, 2026
Back to all postsMicrosoft has acknowledged and is working on resolving an issue affecting Exchange Online users that causes email messages to be automatically quarantined. This problem, which reportedly began on April 7th, 2021, appears to be triggered by specific email content containing 'System.Xml.Linq.XElement' in the subject line or body. The issue can lead to important emails being incorrectly isolated, potentially causing communication disruptions for businesses relying on Exchange Online.
This incident underscores the importance of having robust cybersecurity measures in place, particularly for small and medium-sized Canadian businesses that rely heavily on email communications. The unexpected quarantine of critical messages can lead to productivity losses, customer dissatisfaction, and potential missed business opportunities.
To mitigate this issue, affected businesses should immediately review their email filters and spam rules to ensure they are not inadvertently blocking emails with the problematic content string. It is also recommended to closely monitor email accounts for any unusual activities or missing messages and stay updated on Microsoft's progress in resolving the issue.
Source: BleepingComputer
cybersecurityemailMicrosoftExchange Onlinequarantine
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