User Guide

16 Kaspersky
®
SMTP-Gateway 5.5 for Linux/Unix
2.3.1. Installing the application along
corporate network perimeter
The main advantage of this option is that it improves the overall performance of
your mail system because it minimizes the number of transfer cycles for email
messages.
In this case the existing corporate mail server has no connection to the Internet;
that means additional protection of your data. Moreover, demilitarized zones
(DMZ) may be set up.
To install the application and the mail system on the same server, the following
algorithm is provided to ensure their joint operation:
1. Configure all interfaces of Kaspersky SMTP-Gateway to listen on
port 25 for incoming email traffic from all IP addresses matching the
relevant MX records for the protected domain.
2. The application will scan email traffic and then transfer the
processed messages to the corporate mail system via a different
port (e.g., 1025).
You have to set up restrictions for the mail transfer agent
(MTA) receiving mail from Kaspersky SMTP-Gateway via port
1025 so that it accepts messages exclusively from Kaspersky
SMTP-Gateway. Otherwise, there will be an opportunity to
bypass the protection with a connection established directly
from external network through port 1025.
3. The mail system, configured to use a local interface, will deliver
messages to users.
The following steps are to be followed in order to install the application
and the mail system on the same server:
• Configure the application for mail receipt via port 25 on all network
interfaces of the server. In order to do this, specify the following value in
the [smtpgw.network] section of the configuration file:
ListenOn=0.0.0.0:25
The application, being a mail relay, does not include a local mail
delivery agent (MDA). Therefore, no matter which of the deployment
scenarios is used, a mail system (or mail systems) that delivers email
messages to the local users within the protected domains is required!