Quarantines are temporary mail repositories for holding messages need further processing.
Depending on the features licensed, a Cisco Email Security Appliance (ESA) will be initially configured with up to three quarantines.
A message can end up in more than one quarantine for a variety of reasons. For example, if there is a filter created to quarantine emails that may contain offensive material to the "Policy" quarantine and a message is received which matches that filter and has an encrypted attachment that cannot be scanned for viruses, this email will end up in both the "Virus" and the "Policy" quarantine.
Note: The policies governing messages that reside in multiple quarantines are "conservative" in that they do not allow a message to be delivered from a quarantine, unless that message has been released from all of the quarantines in which it resides.
For more information about quarantines, see the Email Security End-User Guides.