Cisco Cisco Email Security Appliance C160 Mode D'Emploi

The sender verification exception table is a list of domains or email addresses that will either be 
automatically allowed or rejected during the SMTP conversation. You can also specify an optional 
SMTP code and reject response for rejected domains. There is only one sender verification exception 
table per Cisco IronPort appliance and it is enabled per mail flow policy.

The sender verification exception table can be used to list obviously fake but correctly formatted 
domains or email addresses from which you want to reject mail. For example, the correctly formatted 
MAIL FROM: 

pres@whitehouse.gov

 could be listed in the sender verification exception table and set 

to be automatically rejected. You can also list domains that you want to automatically allow, such as 
internal or test domains. This is similar to envelope recipient (SMTP RCPT TO command) processing 
which occurs in the Recipient Access Table (RAT).

The sender verification exception table is defined in the GUI via the Mail Policies > Exception Table 
page (or the CLI, via the 

exceptionconfig

 command) and then is enabled on a per-policy basis via the 

GUI (see 

) or the CLI 

(see the Cisco IronPort AsyncOS CLI Reference Guide.

Entries in the sender verification exception table have the following syntax:

 for more information about 

modifying the exception table.

This section provides an example of a typical conservative implementation of host and envelope sender 
verification.

For this example, when implementing host sender verification, mail from connecting hosts for which 
reverse DNS lookup does not match is throttled via the existing SUSPECTLIST sender group and 
THROTTLED mail flow policy.

A new sender group (UNVERIFIED) and a new mail flow policy (THROTTLEMORE) are created. Mail 
from connecting hosts which are not verified will be throttled (using the UNVERIFIED sender group 
and the more aggressive THROTTLEMORE mail flow policy) prior to the SMTP conversation.

Envelope sender verification is enabled for the ACCEPTED mail flow policy.