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.
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.
Figure 12-1 Typical Electronic Mail Configuration
Each element is described in detail in Hardware Components.