Hi @Troy Barrak
According to the information provided by Microsoft, it indicates that: Quarantined messages are retained for a default period of time based on why they were quarantined. After the retention period expires, the messages are automatically deleted and are not recoverable.
How long quarantined messages are held in quarantine before they expire varies based on why the message was quarantined. The features that quarantine messages and their corresponding retention periods are described in the following table:
Details:
Manage quarantined messages and files as an admin in EOP
Quarantined email messages in EOP and Defender for Office 365
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