Mail Services (Tasks)

This chapter describes how to set up and administer mail services. If you are not familiar with administering mail services, read Chapter 21, Mail Services (Overview) for an introduction to the components of mail services. This chapter also provides a description of a typical mail service configuration, as shown in Figure 21-1. The following list can help you find groups of related procedures that are covered in this chapter.

• Task Map for Mail Services

• Setting Up Mail Services (Task Map)

• Administering Mail Alias Files (Task Map)

• Administering the Queue Directories (Task Map)

• Administering .forward Files (Task Map)

• Troubleshooting Procedures and Tips for Mail Services (Task Map)

See Chapter 23, 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.

See Chapter 24, What's New With Mail Services (Reference) for a description of the new features that are included in version 8.12 of sendmail. You can also read about changes to mail.local, mailstats, and makemap. Chapter 24, What's New With Mail Services (Reference) also provides a description of a new maintenance command, editmap.

Task Map for Mail Services

The following table refers you to other task maps that focus on a specific group of procedures.

Planning Your Mail System

The following list describes some concerns that should be part of your planning process.

• Determine the type of mail configuration that meets your requirements. This section describes two basic types of mail configuration and briefly lists what you need to set up each configuration. If you need to set up a new mail system or if you are expanding an existing one, you might find this section useful. Local Mail Only describes the first configuration type, and Local Mail and a Remote Connection describes the second type.

• As necessary, choose the systems that are to act as mail servers, mail hosts, and mail gateways.

• Make a list of all the mail clients for which you are providing service and include the location of their mailboxes. This list can help you when you are ready to create mail aliases for your users.

• Decide how you plan to update aliases and forward mail messages. You might set up an aliases mailbox as a place for users to send requests for mail forwarding. Users could also use this mailbox to send requests for changes to their default mail alias. If your system uses NIS or NIS+, you can administer mail forwarding, rather than requiring users to manage mail forwarding. Administering Mail Alias Files (Task Map) provides a list of tasks that are related to aliasing. Administering .forward Files (Task Map) provides a list of tasks that are related to managing .forward files.

After you have completed the planning process, set up the systems on your site to perform the functions that are described in Setting Up Mail Services (Task Map). For other task information, refer to Task Map for Mail Services.

Local Mail Only

The simplest mail configuration, as shown in Figure 22-1, is two or more workstations that are connected to one mail host. Mail is completely local. All the clients store mail on their local disks, and the clients act as mail servers. Mail addresses are parsed by using the /etc/mail/aliases files.

Figure 22-1 Local Mail Configuration

To set up this kind of mail configuration, you need the following.

• The default /etc/mail/sendmail.cf file, which requires no editing, on each mail client system.

• A server that is designated as the mail host. You can make this designation by adding mailhost.domain_name to the /etc/hosts file on the mail host. Then, if you are not running NIS or NIS+, add the mail host IP address line to the /etc/hosts file of all mail clients.

• Unless you are running NIS or NIS+, you need matching /etc/mail/aliases files on any system that has a local mailbox.

• Enough space in /var/mail on each mail client system to hold the mailboxes.

For task information on setting up your mail service, refer to Setting Up Mail Services (Tasks). If you are looking for a particular procedure that is related to setting up your mail service, refer to Setting Up Mail Services (Task Map).

Local Mail and a Remote Connection

The most common mail configuration in a small network is shown in Figure 22-2. One system includes the mail server, the mail host, and the mail gateway that provides the remote connection. Mail is distributed by using the /etc/mail/aliases files on the mail gateway. No name service is required.

Figure 22-2 Local Mail Configuration With a UUCP Connection

In this configuration, you can assume that the mail clients mount their mail files from /var/mail on the mail host. To set up this kind of mail configuration, you need the following.

• The main.cf file on the mail gateway. This file requires no editing if Mail Exchanger (MX) records are used.

• The default /etc/mail/sendmail.cf file on each mail client system. This file does not require any editing.

• A server that is designated as the mail host. You can make this designation by adding mailhost.domain_name to the /etc/hosts file on the mail host. Then, if you are not running NIS or NIS+, you must provide additional information. Add the IP address line for the mail host to the /etc/hosts file of every mail client.

• Unless you are running NIS or NIS+, you need matching /etc/mail/aliases files on any system that has a local mailbox.

• Enough space in /var/mail on the mail server to hold the client mailboxes.

For task information on setting up your mail service, refer to Setting Up Mail Services (Tasks). If you are looking for a particular procedure that is related to setting up your mail service, refer to Setting Up Mail Services (Task Map).