Cisco Cisco Email Security Appliance C170 Betriebsanweisung

Host DNS verification settings for sender groups allow you to classify unverified 
senders prior to the SMTP conversation and include different types of unverified 
senders in your various sender groups.

While the connecting host was subject to Host DNS verification in sender groups 
— prior to the SMTP conversation — the domain portion of the envelope sender 
is DNS verified in mail flow policies, and the verification takes place during the 
SMTP conversation. Messages with malformed envelope senders can be ignored. 
You can add entries to the Sender Verification Exception Table — a list of 
domains and email addresses from which to accept or reject mail despite envelope 
sender DNS verification settings.

Reputation Filtering allows you to classify email senders and restrict access to 
your email infrastructure based on sender’s trustworthiness as determined by the 
IronPort SenderBase Reputation Service. 

For more information, see 

Using the 

listenerconfig

 command, you can configure a listener to not include 

the Received: header by default to all messages received by the listener.

For more information, see “Advanced Configuration Options” in the 
“Customizing Listeners” chapter of the Cisco IronPort AsyncOS for Email 
Advanced Configuration Guide.

You can configure a listener to automatically append a default domain to sender 
addresses that do not contain fully-qualified domain names; these are also known 
as “bare” addresses (such as “joe” vs. “joe@example.com”). 

For more information, see “SMTP Address Parsing Options” in the “Customizing 
Listeners” chapter of the Cisco IronPort AsyncOS for Email Advanced 
Configuration Guide.