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.
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 various Solaris releases.
The following changes have been made in the Solaris 10 7/10 release release:
The default version of sendmail has been updated to 8.14.
The sendmail instance was split into two instances to provide better management of the traditional daemon (svc:/network/smtp:sendmail) and the client queue runner (svc:/network/smtp:sendmail-client).
The system can be configured to automatically rebuild the sendmail.cf and the submit.mc configuration files. The required steps are documented in How to Automatically Rebuild a Configuration File.
By default, the sendmail daemon runs in the new local daemon mode. The local–only mode only accepts incoming mail from the local host or loopback SMTP connections. For instance, mail from a cron job or between local users would be accepted. Outbound mail is routed as expected, only the incoming mail is changed. The -bl option is used to select the local-only mode, also known as the Become Local mode. For more information about this mode, see the sendmail(1M) man page. For instructions on how to change back to the -bd or Become Daemon mode, see How to Use sendmail in the Open Mode.
Starting in the Solaris 10 1/06 release, sendmail supports SMTP using Transport Layer Security (TLS). For more information, see the following:
For a complete list of features in the Solaris 10 1/06 release, see Oracle Solaris 10 9/10 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:
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 smf(5) man page and Chapter 18, 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.
Each element is described in detail in Hardware Components.