Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

When delivering non-bounce mail to your own internal mail server (Exchange, etc.), you should disable 
Bounce Verification tagging for that internal domain. 

AsyncOS considers bounces as mail with a null Mail From address (<>). For non-bounce messages that 
might contain a tagged Envelope Recipient, AsyncOS applies a more lenient policy. In such cases, 
AsyncOS ignores the seven-day key expiration and tries to find a match with older keys as well.

The tagging key is a text string your appliance uses when generating the bounce verification tag. Ideally, 
you would use the same key across all of your appliances so that all mail leaving your domain is tagged 
consistently. That way, if one appliance tags the Envelope Sender on an outgoing message an incoming 
bounce will be verified and delivered even if the bounce is received by a different appliance.

There is a seven day grace period for tags. For example, you may choose to change your tagging key 
multiple times within a seven-day period. In such a case, your appliance will try to verify tagged 
messages using all previous keys that are less than seven days old.

AsyncOS also includes a HAT setting related to Bounce Verification for considering whether untagged 
bounces are valid. The default setting is “No,” which means that untagged bounces are considered invalid 
and the appliance either rejects the message or applies a customer header, depending on the action 
selected on the Mail Policies > Bounce Verification page. If you select “Yes,” the appliance considers 
untagged bounces to be valid and accepts them. This may be used in the following scenario:

Suppose you have a user that wants to send email to a mailing list. However, the mailing list accepts 
messages only from a fixed set of Envelope Senders. In such a case, tagged messages from your user will 
not be accepted (as the tag changes regularly).

Add the domain to which the user is trying to send mail to the Destination Controls table and disable 
tagging for that domain. At this point, the user can send mail without problems.

However, to properly support receiving bounces from that domain (since they will not be tagged) you 
can create a sender group for that domain and enable the Consider Untagged Bounces to be Valid 
parameter in an “Accept” mail flow policy.

Fri Jul 21 16:03:51 2006 Info: Message aborted MID 26603 Receiving aborted by sender

Fri Jul 21 16:03:51 2006 Info: Message finished MID 26603 aborted