Cisco Cisco Email Security Appliance X1070 Mode D'Emploi

Max. Recipients per Time 
Interval

The maximum number of recipients during a specified time period that 
this listener will receive from a unique envelope sender, based on the 
mail-from address. The number of recipients is tracked globally. Each 
listener tracks its own rate limiting threshold; however, because all 
listeners validate against a single counter, it is more likely that the rate 
limit will be exceeded if messages from the same mail-from address are 
received by multiple listeners.

Select whether to use the default maximum recipients, accept unlimited 
recipients, or specify another maximum number of recipients.

Use the Default Mail Flow Policy settings to specify the maximum 
number of recipients and the time interval that will be used by the other 
mail flow policies by default. The time interval can only be specified 
using the Default Mail Flow Policy.

Sender Rate Limit Exceeded 
Error Code

The SMTP code returned when an envelope exceeds the maximum 
number of recipients for the time interval defined for this listener.

Sender Rate Limit Exceeded 
Error Text

The SMTP banner text returned when an envelope sender exceeds the 
maximum number of recipients for the time interval defined for this 
listener.

Exceptions

If you want certain envelope senders to be exempt from the defined rate 
limit, select an address list that contains the envelope senders. See 

 for more information.

Use SenderBase for Flow 
Control

Enable “look ups” to the SenderBase Reputation Service for this 
listener.

Group by Similarity of IP 
Addresses: (significant bits 
0-32) 

Used to track and rate limit incoming mail on a per-IP address basis 
while managing entries in a listener’s Host Access Table (HAT) in large 
CIDR blocks. You define a range of significant bits (from 0 to 32) by 
which to group similar IP addresses for the purposes of rate limiting, 
while still maintaining an individual counter for each IP address within 
that range. Requires “Use SenderBase” to be disabled. For more 
information about HAT significant bits, see “HAT Significant Bits 
Feature” in the “Configuring Routing and Delivery Features” chapter.

Directory Harvest Attack 
Prevention: Maximum 
Invalid Recipients Per Hour

The maximum number of invalid recipients per hour this listener will 
receive from a remote host. This threshold represents the total number 
of RAT rejections and SMTP call-ahead server rejections combined 
with the total number of messages to invalid LDAP recipients dropped 
in the SMTP conversation or bounced in the work queue (as configured 
in the LDAP accept settings on the associated listener). For more 
information on configuring DHAP for LDAP accept queries, see the 
“LDAP Queries” chapter.