Руководство Пользователя для Cisco Cisco Email Security Appliance C680

If the quarantine’s Default Action is set to delete, the message will be deleted 
when the retention time period expires, or when the quarantine overflows.

Overflow occurs when the quarantine is full and more messages are added. In 
this case the messages closest to their expiration date (not necessarily the 
oldest messages) are released first, until enough room is available for the new 
messages. You can configure the Outbreak quarantine so that the following 
actions are performed on messages before they are released due to overflow: 
strip attachments, modify the subject, add an X-Header. 

Because quarantined messages are rescanned whenever new rules are published, 
it is very likely that messages in the Outbreak quarantine will be released prior to 
the expiration time.

Still, it can be important to monitor the Outbreak quarantine if the Default Action 
is set to “delete.” IronPort recommends most users to not set the default action to 
delete. For more information about releasing messages from the Outbreak 
quarantine, or changing the Default Action for the Outbreak Quarantine, see the 
“Quarantines” chapter in the Cisco IronPort AsyncOS for Email Daily 
Management Guide.

Conversely, if you have messages in your Outbreak quarantine that you would like 
to keep in the quarantine longer while you wait for a new virus definition, for 
example, you can delay the expiration of those messages. Keep in mind that 
increasing the retention time for messages can cause the size of the quarantine to 
grow.

If anti-virus scanning is disabled globally (not via a mail policy) while a message 
is in the Outbreak quarantine, the message is not anti-virus scanned when it leaves 
the quarantine, even if anti-virus scanning is re-enabled prior to the message 
leaving the quarantine.

You can use the Virus Outbreak Filters feature without having enabled anti-virus 
scanning on the IronPort appliance (see