Cisco Cisco Email Security Appliance C160 Mode D'Emploi

Lines such as these are added to the mail logs upon DKIM signing:

When you configure an AsyncOS appliance for DKIM verification, the following checks are performed:

AsyncOS checks for the DKIM-Signature field in incoming mail, the syntax of the signature header, 
valid tag values, and required tags. If the signature fails any of these checks, AsyncOS returns a permfail. 

After the signature check is performed, the public key is retrieved from the public DNS record, and the 
TXT record is validated. If errors are encountered during this process, AsyncOS returns a permfail. A 
tempfail occurs if the DNS query for the public key fails to get a response.

After retrieving the public key, AsyncOS checks the hashed values and verifies the signature. If any 
failures occur during this step, AsyncOS returns a permfail.

If the checks all pass, AsyncOS returns a pass.

Tue Aug 28 15:29:54 2007 Info: MID 372 DKIM: signing with dkim-profile - matches 

user@example.com

Tue Aug 28 15:34:15 2007 Info: MID 373 DKIM: cannot sign - no profile matches 

user2@example.com

Create a profile for verifying messages using 
DKIM.

.

(Optional) Create a custom mail flow policy to 
use for verifying incoming messages using 
DKIM.

Configure your mail flow policies to verify 
incoming messages using DKIM.

Define the action that the Email Security 
appliance takes on verified messages.

Associate the action with groups of specific 
senders or recipients.