User Guide

3-27
AsyncOS 9.1.2 for Cisco Email Security Appliances User Guide
Chapter 3 Setup and Installation
Using the System Setup Wizard
• One of the IP interfaces (that you created earlier in the systemsetup command) on which to receive
email.
• The name of the machine(s) to which you want to route email (public listeners only). (This is the
first
smtproutes entry. See Routing Email for Local Domains, page 24-1.)
• Whether or not to enable filtering based on SenderBase Reputation Scores (SBRS) for public
listeners. If enabled, you are also prompted to select between Conservative, Moderate, or Aggressive
settings.
• Rate-limiting per host: the maximum number of recipients per hour you are willing to receive from
a remote host (public listeners only).
• The recipient domains or specific addresses you want to accept email for (public listeners) or the
systems allowed to relay email through the appliance (private listeners). (These are the first
Recipient Access Table and Host Access Table entries for a listener. See Sender Group Syntax,
page 7-4 and Adding Domains and Users For Which to Accept Messages, page 8-3 for more
information.)
Related Topics
• Public Listener, page 3-29
• Private Listener, page 3-31
• Listener Example for C170 and C190 Appliances, page 3-33
Public Listener
Note The following examples of creating a public and private listener apply to C370, C670, X1070, C380,
C680, C390, and C690 appliances only. For C170 and C190 appliances, skip to the next section, Listener
Example for C170 and C190 Appliances, page 3-33.
In this example portion of the
systemsetup command, a public listener named InboundMail is
configured to run on the PublicNet IP interface. Then, it is configured to accept all email for the domain
example.com. An initial SMTP route to the mail exchange exchange.example.com is configured. Rate
limiting is enabled, and the maximum value of 4500 recipients per hour from a single host is specified
for the public listener.
Note The value you enter for maximum recipients per hour you are willing to receive from a remote host is a
completely arbitrary value, one that is usually relative to the size of the enterprise for which you are
administering email. For example, a sender who sends 200 messages in an hour might be considered a
“spammer” (sender of unsolicited bulk email), but if you are configuring the Email Security appliance
to handle all email for a 10,000 person company, 200 messages per hour from a remote host may be a
reasonable value. Conversely, in a 50-person company, someone sending 200 messages in an hour to you
may be an obvious spammer. You must choose an appropriate value when you enable rate-limiting on a
public listener (throttle) inbound email for your enterprise. For more information on Default Host Access
policies, see Sender Group Syntax, page 7-4.
The default host access policy for the listener is then accepted.
You are now going to configure how the appliance accepts mail by
creating a "Listener".