Cisco Cisco Email Security Appliance C160 Mode D'Emploi

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 AsyncOS CLI Reference Guide.

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

See 

 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.

 shows the suggested settings for implementing sender verification:

UNVERIFIED

SUSPECTLIST

THROTTLEMORE

THROTTLED

Prior to SMTP conversation:

Connecting host PTR record does not exist in the DNS.

Connecting host reverse DNS lookup (PTR) does not match 
the forward DNS lookup (A).

ACCEPTED

Envelope Sender Verification during SMTP conversation:

- Malformed MAIL FROM: 

- Envelope sender does not exist in DNS.

- Envelope sender DNS does not resolve.