Software Versions

Most of the examples in this book are taken from Red Hat Linux 7.3 and 8.0, and from Solaris 8. However, the versions of Unix used to create the examples makes very little difference. There are small variations in command output or command-line options, but these variations should not present a problem. sendmail software works the same way from system to system.

Much more important differences are introduced by the version of sendmail. sendmail is constantly evolving. The examples in this book are based on sendmail 8.12, specifically 8.12.9 and 8.12.10. We do not know if the recipes will work exactly as shown on other versions of sendmail, but they should work with minimal adjustments.

Conventions

This book uses the following typographical conventions:

Italic

Indicates the names of files, databases, directories, hostnames, domain names, usernames, sendmail feature names , Unix utilities, programs, and it is used to emphasize new terms when they are first introduced.

Constant width

Indicates sendmail.cf literals, commands and variables , m4 macros and built-in commands, and Unix command-line options. It is used to show the contents of files and the output from commands. Keywords are also in constant width .


Constant width bold

Used in examples to show commands or text that you would type.

Constant width italic

Used in examples and text to show variables for which a context-specific substitution should be made. (The variable filename , for example, would be replaced by some actual filename.)

$ , #

When we demonstrate commands that you would give interactively, we normally use the default Bourne shell prompt ( $ ). If the command must be executed as root , then we use the default superuser prompt ( # ).

[ option ]

When showing command syntax, we place optional parts of the command within brackets. For example, ls [ -l ] means that the -l option is not required.

This icon signifies a tip, suggestion, or general note.

This icon indicates a warning or caution.

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Acknowledgments

No book is the product of one person. This one certainly is not! I have many people to thank for their help in producing the book.

The idea for this book came originally from Tim O'Reilly. Mike Loukides explained the idea of the book to me, and I knew I wanted to write it. Tim and Mike deserve thanks for getting the ball rolling.

Two editors have supported me through the long and difficult process of producing this book. Jim Sumser worked with me during the first phase of writing and Simon St.Laurent brought me through to the finish line. Both of these guys have been a great help.

I particularly want to thank my technical reviewers, Greg Shapiro, Claus Assmann, and Nick Christenson. You could not ask for a better technical team. Look at the list of authors for the Sendmail Installation and Operations Guide and you'll see Greg and Claus listed there. You'll also see Greg's name on most of the sample configurations provided with the sendmail distribution ”no one knows more about sendmail configuration than Greg. As for Nick, he is the author of the book sendmail Performance Tuning (Addison Wesley) that Eric Allman simply calls "great." These guys know sendmail and they took the time to meticulously review every page of this book. Their help and insight were invaluable. This is a much better book because of their involvement.

I also want to thank the crew at O'Reilly. Thanks to Marlowe Shaeffer, production editor and proofreader, for getting this book through; Derek Di Matteo for copyediting; Ellie Volckhausen for her work on the cover; and Tom Dinse for the indexing.

Finally, I want to thank my family for having the patience to put up with me when I have no patience left.