A policy quarantine is a type of quarantine that allows Cisco ESA to store messages that match certain criteria, such as virus, spam, or DLP verdicts, for further review or release by an administrator or an end user. A scenario that prevents a message from being sent to the quarantine as an action in the scan behavior on Cisco ESA is when a policy quarantine is missing, which means that no policy quarantine has been created or enabled on Cisco ESA. The other options do not prevent a message from being sent to the quarantine as an action in the scan behavior on Cisco ESA.