Introduction

SpamAssassin is an open-source spam detector. It is considered the best of breed, and is used by many large organizations and also as the basis for commercial services and products.

SpamAssassin is free to download, install, and use, and is very customizable, configurable, and scalable to large architectures. It can be installed in one afternoon, but rewards further time spent on improving the detection rate.

This book provides a complete guide to the installation, configuration, and customization of SpamAssassin. It also discusses the history of Spam and the various techniques used to combat it. It includes detailed instructions for the most popular Mail Transport Agents (MTAs): Sendmail, Postfix, Exim, and Qmail. It also includes details on installing SpamAssassin on Windows, and adding a separate spam filter to an existing email infrastructure, such as Microsoft Exchange.

Most spam detection systems use only one or two methods of detecting spam. SpamAssassin uses many, and is extensible, allowing users to develop their own rules to identify spam. New techniques to identify spam, such as Sender Policy Framework (SPF) can be added to SpamAssassin by developing them as modules. Users or System Administrators can configure almost every aspect of SpamAssassin, leading to exceptional success rates in detecting spam.

SpamAssassin is Open Source, which means that the program code is freely available for others to examine and modify. SpamAssassin is developed, documented, and supported by a team of volunteers who give their time freely.