Setting up and maintaining an electronic mail service involves complex tasks that are critical to the daily operation of your network. As a network administrator, you might need to expand an existing mail service. Alternately, you might need to set up a mail service on a new network or a subnet. The chapters on mail services can help you plan and set up a mail service for your network. This chapter provides links to descriptions 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 With Mail Services Other sendmail Information Sources Introduction to the Components of Mail Services See Chapter 13, Mail Services (Tasks) for procedural information about how to set up and administer mail services. For details, refer to Task Map for Mail Services.See Chapter 14, 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, the interactions of sendmail with name services, and the features in version 8.13 of sendmail. See Changes in Version 8.13 of sendmail. This section provides information about new features in the Solaris 10 release and the Solaris 10 1/06 release.Starting in the Solaris 10 1/06 release, sendmail supports SMTP using Transport Layer Security (TLS). For more information, see the following:Support for Running SMTP With TLS in Version 8.13 of sendmail Setting SMTP to Use TLS For a complete list of features in the Solaris 10 1/06 release, see Solaris Express, Developer Edition What’s New. Starting in the Solaris 10 release, sendmail version 8.13 is the default. For information about version 8.13 and other changes, see the following:Flags Used and Not Used to Compile sendmail MILTER, Mail Filter API for sendmail Versions of the Configuration File Enhancement for vacation Utility Contents of the /etc/mail/cf Directory Changes in Version 8.13 of sendmail Support for TCP Wrappers From Version 8.12 of sendmail Additionally, the mail service is managed by the Service Management Facility. Administrative actions on this service, such as enabling, disabling, or restarting, can be performed by using the svcadm command. The service's status can be queried by using the svcs command. For more information about the Service Management Facility, see the smf5 man page and Chapter 14, Managing Services (Overview), in System Administration Guide: Basic Administration. The following is a list of additional information sources about sendmail.Costales, Bryan. sendmail, Third Edition. O'Reilly & Associates, Inc., 2002. 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 versions of sendmail – http://www.sendmail.org/vendor/sun/. Many software and hardware components are required to establish a mail service. The following sections give a quick introduction to these components. These sections also provide some of the terms that are used to describe the components.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.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.Component Description .forward files Files that you can set up in a user's home directory to redirect mail or to send mail to a program automatically mailbox A file on a mail server that is the final destination for email messages mail addresses Address that contains the name of the recipient and the system to which a mail message is delivered mail aliases An alternate name that is used in a mail address mail queue A collection of mail messages that needs to be processed by the mail server postmaster A special mail alias that is used to report problems and to ask questions about the mail service sendmail configuration file A file that contains all the information necessary for mail routing 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 12–1 shows a typical electronic mail configuration, using the three basic mail elements plus a mail gateway.

Diagram shows the dependencies between a mail gateway, a mail host, mail servers, mailboxes, clients.

Each element is described in detail in Hardware Components.