Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

Messages are also released from the Outbreak quarantine after CASE’s recommended retention period 
has elapsed. CASE calculates the retention period based on the message’s threat level. You can define 
separate maximum retention times for virus outbreaks and non-viral threats. If CASE’s recommended 
retention time exceeds the maximum retention time for the threat type, the Email Security appliance 
releases messages when the maximum retention time elapses. For viral messages the default maximum 
quarantine period is 1 day. The default period for quarantining non-viral threats is 4 hours. You can 
manually release messages from the quarantine.

The Email Security appliance also releases messages when the quarantine is full and more messages are 
inserted (this is referred to as overflow). Overflow only occurs when the Outbreak quarantine is at 100% 
capacity, and a new message is added to the quarantine. At this point, messages are released in the 
following order of priority:

Messages quarantined by Adaptive Rules (those scheduled to be released soonest are first)

Messages quarantined by Outbreak Rules (those scheduled to be released soonest are first)

Overflow stops the moment the Outbreak quarantine is below 100% capacity. For more information 
about how quarantine overflow is handled, see the “Quarantines” chapter in the Cisco IronPort AsyncOS 
for Email Daily Management Guide.

Messages released from the Outbreak quarantine are scanned by the anti-virus and anti-spam engines 
again if they’re enabled for the mail policy. If it is now marked as a known virus or spam, then it will be 
subject to your mail policy settings (including a possible second quarantining in the Virus quarantine or 
Cisco IronPort Spam quarantine). For more information, see 

Thus it is important to note that in a message's lifetime, it may actually be quarantined twice — once 
due to the Outbreak Filters feature, and once when it is released from the Outbreak quarantine. A 
message will not be subject to a second quarantine if the verdicts from each scan (prior to Outbreak 
Filters, and when released from the Outbreak quarantine) match. Also note that the Outbreak Filters 
feature does not take any final actions on messages. The Outbreak Filters feature will either quarantine 
a message (for further processing) or move the message along to the next step in the pipeline.

Very early in a virus outbreak’s lifecycle, broader rules are used to quarantine messages. As more 
information becomes available, increasingly focused rules are published, narrowing the definition of 
what is quarantined. As the new rules are published, messages that are no longer considered possible 
virus messages are released from quarantine (messages in the outbreak quarantine are rescanned as new 
rules are published).

T=0

Adaptive Rule 
(based on past 
outbreaks)

A consolidated rule set based 
on over 100K message 
attributes, which analyzes 
message content, context and 
structure

Messages are automatically quarantined 
if they match Adaptive Rules

T=5 min Outbreak Rule

Quarantine messages 
containing .zip (exe) files

Quarantine all attachments that are .zips 
containing a .exe