Cisco Cisco Email Security Appliance C170 Guia Do Utilizador

6-7

Cisco AsyncOS 8.0.2 for Email User Guide

Chapter 6 Reputation Filtering

Entering Low SBRS Scores in the Message Subject

Monitoring the Status of the SenderBase Reputation Service

The SenderBase page in the Security Services menu displays the connection status and the timestamp of
the most recent query from the Cisco appliance to the SenderBase Network Status Server and
SenderBase Reputation Score Service. The SenderBase Reputation Score Service sends the SRBS scores
to the appliance. The SenderBase Network Server sends the appliance information about the IP
addresses, domains, and organizations that are sending mail to you. AsyncOS uses this data for its
reporting and email monitoring features.

Figure 6-3

SenderBase Network Status on the SenderBase Page

The

sbstatus

command in CLI displays the same information.

Entering Low SBRS Scores in the Message Subject

Although Cisco recommends throttling, an alternate way to use the SenderBase Reputation Service is to
modify the subject line of suspected spam messages. To do this, use the message filter shown in

Table 6-2

. This filter uses the

reputation

filter rule and the

strip-header

and

insert-header

filter

actions to replace the subject line of messages having a SenderBase Reputation Score lower than -2.0
with a subject line that includes the actual SenderBase Reputation Score represented as:

{Spam

SBRS

}

Replace listener_name in this example with the name of your public listener. (The period on its own line
is included so that you can cut and paste this text directly into the command line interface of the

filters

command.)

Table 6-2

Message Filter to Modify Subject Header with SBRS: Example 1

sbrs_filter:

if ((recv-inj == "listener_name" AND subject != "\\{Spam -?[0-9.]+\\}"))

{

insert-header("X-SBRS", "$REPUTATION");

if (reputation <= -2.0)

{

strip-header("Subject");

insert-header("Subject", "$Subject \\{Spam $REPUTATION\\}");

}