How This Book Is Organized

Although you could read this book cover-to-cover, it is designed to be flexible and allow you to easily move between chapters and sections of chapters to cover only the material you need. If you do intend to read them all, the order in which they are presented is an excellent sequence.

Chapters 1 through 15 cover the following topics:

• Chapter 1, “Introduction to Email Security”: This chapter provides an introduction to the Cisco ESA and the AsyncOS software, their history and features, and an overview of the problems it is designed to solve. This chapter also covers the basics of SMTP and its dependency on DNS. The history and nature of SMTP abuses are explored.

• Chapter 2, “ESA Product Basics”: This chapter gives an overview of all the ESA features and the basic connection and setup process. It reviews differences between the various hardware models. The chapter walks you through the System Setup Wizard step by step, and then reviews the configuration you’ll have after completing it. After showing a simple deployment example, more complex network installations are discussed.