We began previous editions of this book
with a very long tutorial aimed at those new to
sendmail. In this edition, however, much of that
tutorial has been folded into the chapters that follow, and we
present, instead, a brief introductory chapter intended to get new
people started. It begins with a look at some of the basic concepts
of email and the sendmail program. We will show
you sendmail's basic parts,
explore the three parts of an email message, then demonstrate how to
run sendmail by hand. We finish with an overview
of the roles sendmail plays and of its various
modes, and lastly, we take a preliminary look at its configuration
file.
