What This Book Covers
This book has three main areas or sections. The first section discusses spam, spammers, and anti-spam techniques. The second section discusses SpamAssassin basics, including obtaining, installing, and configuring SpamAssassin. The final section describes techniques to improve the spam detection of SpamAssassin, and to improve the performance of a SpamAssassin installation.
Chapter 1 introduces spam and provides some definitions of terms used in this book.Chapter 2 discusses various spam detection techniques used by spam detection engines and the techniques developed by spammers to subvert them.
Chapter 3 discusses open relays, historically the source of much spam, and includes information on how to check that an existing email server cannot be abused by spammers. It also describes how to rectify an MTA that is acting as an open relay. Chapter 4 describes how spammers collect email addresses and provides solutions to publish email addresses on websites without making them targets for spam.Chapter 5 discusses the mechanics of detecting spam.
Chapter 6 gives detailed instructions on how to install SpamAssassin on Unix, Linux, and Windows platforms, including obtaining and installing any prerequisite packages that SpamAssassin requires.
Chapter 7 provides a brief run through the SpamAssassin configuration files, and provides a foundation for the remaining chapters. Chapter 8 discusses how to integrate SpamAssassin with the MTA, or invoke it using procmail. A variety of strategies are discussed, to suit the needs of different organizations.
Chapter 9 covers the use of SpamAssassin’s Bayesian filter, a tool that learns from spam emails and can improve detection rates dramatically.
SpamAssassin is incredibly flexible, and Chapter 10 discusses how SpamAssassin can alter emails to mark them as spam.Chapter 11 covers adding external Network Tests which utilize databases of known spam emails to improve spam detection rates.
Chapter 12 provides a description of SpamAssassin’s rules, and describes how rules can be written, tested, and scored.
Chapter 13 covers methods to improve the detection rate of SpamAssassin, including whitelists and blacklists.
Chapter 14 describes how to improve the performance of a SpamAssassin installation.
Chapter 15 describes some useful reports and utilities that an administrator can use to streamline the running of a SpamAssassin installation.
Chapter 16 has a complete description of how to create a spam filtering gateway—this covers installing Linux and SpamAssassin, and configuring them all to filter email and forward the non-spam (or ‘ham’) to the existing email server.
Chapter 17 describes how to configure several major email clients to filter email based on the tags that SpamAssassin places in emails.
Finally, Chapter 18 discusses the advantages, disadvantages, and options available when adding an additional spam filter to an existing SpamAssassin installation.