Chapter 24 Mail Services (Overview)

To set up an electronic mail service and maintain it are complex tasks, both of which are critical to the daily operation of your network. As a network administrator, you need to expand an existing mail service, or perhaps you might need to set up a mail service on a new network or subnet. The chapters on mail services can help you plan and set up a mail service for your network. This chapter provides a list of new features in sendmail, as well as a list of other sources of information. The chapter also provides overviews of the software and hardware components that are required to establish a mail service.

• "What's New in Version 8.12 of sendmail"

• "Introduction to the Components of Mail Services"

Look in Chapter 25, Mail Services (Tasks) for procedural information on how to set up and administer mail services. For details, refer to "Mail Services Task Map".

Look in Chapter 26, Mail Services (Reference) for a more detailed description of the components of mail services. This chapter also describes the mail service programs and files, the mail routing process, and the interactions of sendmail with name services.

What's New in Version 8.12 of sendmail

Version 8.12 of sendmail has been included in this Solaris 9 release. Chapter 27, What's New With Mail Services (Reference) describes all of its new features. The following list highlights some of the important changes to sendmail.

• "New Configuration File, submit.cf"

• "New or Deprecated Command-Line Options"

• "New and Revised Configuration File Options and Related Topics"

• "New and Revised m4 Configuration Macros for sendmail"

• "New Delivery Agent Flags"

• "New Equates for Delivery Agents"

• "Changes to Files"

Chapter 27, What's New With Mail Services (Reference) also describes these other changes.

• "Changes to mail.local"

• "Changes to mailstats"

• "Changes to makemap"

• "New Command, editmap"

• "Other Changes and Features of Interest"

Other sendmail Information Sources

The following is a list of additional information sources about sendmail.

• Costales, Bryan. sendmail, Second Edition. O'Reilly & Associates, Inc., 1997.

• Home page for sendmail - http://www.sendmail.org

• FAQ for sendmail - http://www.sendmail.org/faq

• README for new sendmail configuration files - http://www.sendmail.org/m4/readme.html

• A guide for issues that are related to migrating to more recent 8.*+Sun versions of sendmail - http://www.sendmail.org/vendor/sun/

Introduction to the Components of Mail Services

Many software and hardware components are required to establish a mail service. The following sections give a quick introduction to these components and some of the terms that are used to describe them.

The first section, "Overview of the Software Components", defines the terms that are used when discussing the software parts of the mail delivery system. The next section, "Overview of the Hardware Components", focuses on the functions of the hardware systems in a mail configuration.

Overview of the Software Components

The following table introduces some of the software components of a mail system. Refer to "Software Components" for a complete description of all of the software components.

Overview of the Hardware Components

A mail configuration requires three elements, which you can combine on the same system or provide in separate systems.

• A mail host - A system that is configured to handle email addresses that are difficult to resolve

• A minimum of one mail server - A system that is configured to hold one or more mailboxes

• Mail clients - Systems that access mail from a mail server

If users are to communicate with networks outside your domain, you must also add a fourth element, a mail gateway.

Figure 24-1 shows a typical electronic mail configuration, using the three basic mail elements plus a mail gateway.

Figure 24-1 Typical Electronic Mail Configuration

Each element is described in detail in "Hardware Components".