Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

The Incoming Relays feature helps your Cisco IronPort appliance obtain the IP 
address of an external machine that is sending mail to the Cisco IronPort 
appliance via one or more mail exchange/transfer agents (MX or MTA), filtering 
servers, etc. at the edge of the network. In this type of configuration, the IP 
address of the external machine is not automatically known by the Cisco IronPort 
appliance. Instead, mail appears to originate from the local MX/MTA (the 
incoming relay) rather than from the external machine. IronPort Anti-Spam and 
IronPort Intelligent Multi-Scan depend on accurate IP addresses for external 
senders so it is vital for the Cisco IronPort appliance to have this information.

You should only enable this feature if you have a local MX/MTA relaying mail to 
your Cisco IronPort appliance.

 shows a very basic example of an incoming relay. Mail from IP 

address 7.8.9.1 appears to come from IP address 10.2.3.4 because the local 
MX/MTA is relaying mail to the Cisco IronPort appliance.

 

IronPort Email Security appliance

Firewall

MX / MTA

Sending
Machine

IP: 7.8.9.1

IP: 10.2.3.4

IP: 10.2.3.5