While you can download the source code for Sendmail and build your own copy, many users prefer to install Sendmail via RPM from the CD-ROM (at the time of the Red Hat Linux installation or at a later point).
The Sendmail application is placed in /usr/sbin.
Sendmail's lengthy and detailed configuration file (sendmail.cf) is installed in /etc. You should not edit the sendmail.cf file directly unless you know exactly what you are doing, due to the fact it is very lengthy and complex. Instead, to make configuration changes to Sendmail, edit the /etc/mail/sendmail.cf file and use the included m4 macro processor to create a new /etc/sendmail.cf (after backing up the original /etc/sendmail.cf, of course). More information on configuring Sendmail can be found in the section called Common Configuration Changes.
Various Sendmail configuration files are installed in /etc/mail including:
access — Specifies which systems can use Sendmail for relaying email.
domaintable — Allows you to provide domain name mapping.
local-host-names — The place where you include all aliases for your machine.
mailertable — Specifies instructions that override routing for particular domains.
virtusertable — Permits you to do a domain-specific form of aliasing, allowing multiple virtual domains to be hosted on one machine.
Several of the configuration files in /etc/mail, such as access, domaintable, mailertable and virtusertable, must actually store their information in database files before Sendmail can use any configuration changes. To include any changes you make to these configuration in their database files, you must run a command with the syntax makemap hash /etc/mail/name < /etc/mail/name where name is the name of the configuration file to convert.
For example, if you want all email addressed to any domain.com account to be delivered to <[email protected]>, you need to add a line to the virtusertable file:
@domain.com [email protected] |
Then, to add this new information to the virtusertable.db file, execute makemap hash /etc/mail/virtusertable < /etc/mail/virtusertable as root. This will create a new virtusertable.db that contains the new configuration.