Book Image

SpamAssassin: A practical guide to integration and configuration

Book Image

SpamAssassin: A practical guide to integration and configuration

Overview of this book

As a busy administrator, you know Spam is a major distraction in todays network. The effects range from inappropriate content arriving in the mailboxes up to contact email addresses placed on a website being deluged with unsolicited mail, causing valid enquiries and sales leads to be lost and wasting employee time. The perception of the problem of spam is as big as the reality. In response to the growing problem of spam, a number of free and commercial applications and services have been developed to help network administrators and email users combat spam. Its up to you to choose and then get the most out of an antispam solution. Free to use, flexible, and effective, SpamAssassin has become the most popular open source antispam application. Its unique combination of power and flexibility make it the right choice. This book will now help you set up and optimize SpamAssassin for your network.
Table of Contents (24 chapters)
SpamAssassin
Credits
About the Author
About the Reviewers
Introduction
Glossary

RBLs


A number of RBLs are enabled with the default configuration of SpamAssassin. These are defined in /usr/share/spamassassin/20_dnsbl_tests.cf. An example definition is shown here:

header RCVD_IN_NJABL eval:check_rbl('njabl', 'dnsbl.njabl.org.')
describe RCVD_IN_NJABL Received via a relay in dnsbl.njabl.org
tflags RCVD_IN_NJABL net

One set of definitions appears for each RBL configured. Rule definitions are explained in more detail in Chapter 12.

All the rules include a line that sets tflags to net. This groups the rules as network tests, and allows SpamAssassin to treat them as a group. There are two main reasons for this. The first is that network tests may take a long time to complete, especially at busy times. SpamAssassin uses a timeout for network tests, but it also applies this timeout in a progressive manner. If most of the network tests have completed, SpamAssassin will not wait for the last tests to complete. Specific details are given in the Mail::SpamAssassin::Conf main page...