Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

Enter the IP address of the MTA, MX, or other machine that connects to the Email Security appliance to 
relay incoming messages. 

You can use IPv4 or IPv6 addresses, standard CIDR format, or an IP address range. For example, if you 
have several MTAs at the edge of your network receiving email, you might want to enter a range of IP 
addresses to include all of your MTAs, such as 10.2.3.1/8 or 10.2.3.1-10. 

For IPv6 addresses, AsyncOS supports the following formats:

2620:101:2004:4202::0-2620:101:2004:4202::ff

2620:101:2004:4202::

2620:101:2004:4202::23

2620:101:2004:4202::/64

Specify the header that will identify the IP address of the original external sender. 

When entering a header, you do not need to enter the trailing colon. 

Select the header type: 

Choose custom headers (recommended) or Received headers. 

For custom headers: 

Enter the header name that you configured the relaying machine to add to relayed messages. 

For example: 

SenderIP 

or 

X-CustomHeader 

For Received headers: 

Enter the character or string after which the IP address will appear. Enter the number for the “hop” 
to check for the IP address. 

Submit and commit your changes.

Consider doing the following: 

Add the relaying machine to a sender group with a mail flow policy that has unlimited messages for 
DHAP. For an explanation, see 

To facilitate tracking and troubleshooting, configure the appliance logs to show which header is 
used. See 

You will configure your appliance to use one of the following types of header to identify the original 
sender of a relayed message: