Cisco Cisco Email Security Appliance C680 User Guide

* These features can send messages to special queues called Quarantines.

** Can send messages to the Cisco IronPort Spam Quarantine.

The receiving phase of the Email Pipeline involves the initial connection from the sender’s host. Each 
message’s domains can be set, the recipient is checked, and the message is handed off to the work queue.

The HAT allows you to specify hosts that are allowed to connect to a listener (that is, which hosts you 
will allow to send email). 

Sender Groups are used to associate one or more senders into groups, upon which you can apply message 
filters, and other Mail Flow Policies. Mail Flow Policies are a way of expressing a group of HAT 
parameters (access rule, followed by rate limit parameters and custom SMTP codes and responses).

Together, sender groups and mail flow policies are defined in a listener’s HAT.

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 Cisco IronPort SenderBase Reputation Service. 

For more information, see 

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1. Sets the default delivery interface. 

2. Sets the total maximum number of 
outbound connections. 

Defines, per-domain: maximum outbound 
connections for each virtual gateway and for 
the entire system; the bounce profile to use; 
the TLS preference for delivery: 
no/preferred/required

Routes mail based on domain without 
rewriting Envelope Recipient.

Drops recipients according to specific list 
(configured system-wide). 

Undeliverable message handling. 
Configurable per listener, per Destination 
Controls entry, and via message filters.