PMDF System Manager's Guide

Before setting up an e-mail firewall, you have presumably already set up a general firewall or "Internet firewall" to control general sorts of TCP/IP connections, etc., to your systems. Note that in comparison with remote logins or FTP access to files on your systems, e-mail is generally much less of an overall security exposure; there is generally not much point to concerning oneself with e-mail security until more fundamental security issues have been addressed. The discussion on e-mail firewalls in this chapter is referring solely to the additional control of e-mail that you may want to impose when you already have an Internet firewall set up.