Email quarantine
Email quarantine holds messages apart from normal mailbox delivery because a security or mail policy flagged them, with access and release controlled by the service's settings.
Why a message was held
A quarantine decision reflects a detection or policy match. The message may be dangerous, or it may be a legitimate message caught by the filter. Review the reason and the message rather than treating the label alone as a final verdict.
Quarantine also differs from a user’s Junk Email folder. Access and release are governed by quarantine permissions. In Microsoft 365, policy settings can let a recipient release some messages, request an administrator’s review, or take neither action. The available choice also depends on the threat category.
A release request is not a release
A recipient may be allowed to ask an administrator for release without being allowed to release the message themselves. Even after release, other filtering services or inbox rules can affect where the message ends up.
A release also need not authorize future messages from the same sender. Some workflows offer additional allow options, so check what was actually selected. Our release guide explains how those decisions differ.
For attachments that lead to another download, see how HTML attachment lures work.