Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

In the Cisco IronPort AsyncOS for Email Configuration Guide, you learned how 
the IronPort AsyncOS operating system allows the IronPort appliance to function 
as the inbound email gateway for your enterprise, servicing SMTP connections 
from the Internet, accepting messages, and relaying messages to the appropriate 
systems by enabling listeners to service these connections.

A listener describes an email processing service that will be configured on a 
particular IP interface. Listeners only apply to email entering the IronPort 
appliance — either from the internal systems within your network or from the 
Internet. IronPort AsyncOS uses listeners to specify criteria that messages must 
meet in order to be accepted and relayed to recipient hosts. You can think of a 
listener as an “email injector” or even a “SMTP daemon” running on a specific 
port for each IP address you specify (including the initial addresses you 
configured with the System Setup Wizard or 

systemsetup

 command). 

If you have completed the GUI’s System Setup Wizard (or the Command Line 
Interface 

systemsetup

 command) as described in the “Setup and Installation” 

chapter of the Cisco IronPort AsyncOS for Email Configuration Guide and 
committed the changes, at least one listener should already be configured on your 
appliance. 

This chapter describes how to use the Listeners page on the Network menu in the 
GUI or the 

listenerconfig

 CLI command to customize some of the advanced 

receiving properties of listeners configured on your IronPort appliance, including 
creating new listeners. The following chapter, 

 describes how to customize the delivery properties of 

listeners configured on the system.