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.
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.
Chapter 27, What's New With Mail Services (Reference) also describes these other changes.
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.
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 ask questions about the mail service |
sendmail configuration file | A file that contains all the information necessary for mail routing |
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".