Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

“Black hole” listeners allow you to test your message generation systems and to also get a rough measure 
of receiving performance. Two types of black hole listeners are queueing and non-queueing. 

The queueing listener saves the message to the queue, but then immediately deletes it. Use a queuing 
listener when you are interested in measuring the performance of the entire injection portion of your 
message generation system. 

The non-queueing listener accepts a message, and then immediately deletes it without saving it. Use 
the non-queueing listener when you want to troubleshoot the connection from your message 
generation system to the appliance. 

For example, in 

, you could create a black hole listener “C” to mirror the private listener 

labeled “B.” A non-queueing version tests the performance path of the system from the groupware client 
to the groupware server to the appliance. A queueing version tests that same path and the appliance’s 
ability to enqueue messages and prepare them for delivery via SMTP.