Cisco Cisco Email Security Appliance C160 Mode D'Emploi

A global configuration option exists to allow you to adjust when the injection control counters are reset. 
For very busy systems maintaining counters for a very large number of different IP addresses, 
configuring the counters to be reset more frequently (for example, every 15 minutes instead of every 60 
minutes) will ensure that the data does not grow to an unmanageable size and impact system 
performance.

The current default value is 3600 seconds (1 hour).You can specify periods ranging from as little as 1 
minute (60 seconds) to as long as 4 hours (14,400 seconds). 

Adjust this period via the GUI, using the global settings (for more information, see 

You can also adjust this period using the 

listenerconfig -> setup

 command in the CLI. For more 

information on listenerconfig command, see the CLI Reference Guide for AsyncOS for Cisco Email 
Security Appliances.

Spam and unwanted mail is frequently sent by senders whose domains or IP addresses cannot be resolved 
by DNS. DNS verification means that you can get reliable information about senders and process mail 
accordingly. Sender verification prior to the SMTP conversation (connection filtering based on DNS 
lookups of the sender’s IP address) also helps reduce the amount of junk email processed through the 
mail pipeline on the appliance.

Mail from unverified senders is not automatically discarded. Instead, AsyncOS provides sender 
verification settings that allow you to determine how the appliance handles mail from unverified senders: 
you can configure your appliance to automatically block all mail from unverified senders prior to the 
SMTP conversation or throttle unverified senders, for example.

The sender verification feature consists of the following components: 

Verification of the connecting host. This occurs prior to the SMTP conversation. For more 
information, see 

Verification of the domain portion of the envelope sender. This occurs during the SMTP 
conversation. For more information, see 

Senders can be unverified for different reasons. For example, the DNS server could be “down” or not 
responding, or the domain may not exist. Host DNS verification settings for sender groups allow you to 
classify unverified senders prior to the SMTP conversation and include different types of unverified 
senders in your various sender groups.