Chapter 3. Planning Mail Services

This chapter describes the following four basic mail configurations and outlines the tasks required to set up each configuration. All of the information in this chapter is new in this edition.

• Single DNS domain with an Internet connection and a combined mail hub and gateway.

• Single DNS domain with Internet connection and separate gateway.

• DNS domain and a subdomain with one Internet connection.

• DNS domain with a UUCP gateway.

You may find the following sections useful if you need to set up a new mail system or are expanding an existing one. The configurations start with a basic case (a single DNS domain connected to the Internet) and increase in complexity to a two-domain configuration with Internet and UUCP gateways. More complex systems are beyond the scope of this book.

To set up a mail system, regardless of its configuration, you need the following elements.

• A sendmail.cf configuration file on each system.

• Alias files with an alias for each user to point to the place where mail is to be delivered.

• A mailbox to store (or spool) mail files for each user.

• A postmaster alias for the person who administers mail services.

See Chapter 4, “Setting Up and Administering Mail Services,” for detailed information on how to set up these elements.

How you set up the configuration file and the alias file and where you put the mailboxes depend on the configuration you choose.