Sendmail is the most popular electronic mail server software widely used on the Internet. It is the oldest and most mature mail server software that has stood the test of time. It is also the most complex software to understand and administer for system administrators. Given the fact that electronic mail evolved into one of the most commonly used utilities, understanding and administering the backend mail server is crucial.

This book is one of the most comprehensive resources on the topic, and covers almost everything about building, installing, and administering Sendmail. This book is so popular that everyone working with mail servers in the system administration community must have at least heard of this book, often by the nickname “The Bat Book.” (The front cover of this book carries a picture of a bat).

No matter how many books on Sendmail you have read, if you are looking for a comprehensive Sendmail guide, you must own a copy of this one. I had a wonderful reading experience with this third edition. With over 1,200 pages, this book is packed with theory, examples, and illustrations. Given the significant differences between Sendmail 8.10 and the latest 8.12 version, this edition is a must for any system administrator or Sendmail engineer. Also, this edition is much better than the second edition in terms of clarity of presentation of the subject matter.

This book is best used as a reference in the everyday life of a system administrator or engineer responsible for administering Sendmail. Knowledge of C programming and some practical experience working with Sendmail servers are required. Without this book, it would take countless hours and enormous effort to gather information about Sendmail. Information presented in this edition is useful for managing commercial and freeware Sendmail servers (which run on Unix flavors), but not Sendmail Advanced Server (which runs on the Windows NT platform). There is no discussion of running Sendmail in chroot jail, although this is not usually necessary because of robust security built into the latest versions of Sendmail.

This book has 25 chapters, five appendices, a bibliography, and an index. Chapter 1 covers basics of Sendmail. Chapters 2 through 5 are grouped into Part 1 and cover building and installing Sendmail. Part 2 contains chapters 6 through 16, which cover administering Sendmail, including performance tuning, anti-spam measures, testing rule sets, and security issues. Part 3 contains chapters 17 through 25, which cover the crux of Sendmail configuration files in detail.