Red Hat ENTERPRISE LINUX 3 Reference Manual page 184

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Note
This is only for a very basic configuration of Sendmail with LDAP. The configuration can differ greatly
from this depending on the implementation of LDAP, especially when configuring several Sendmail
machines to use a common LDAP server.
Consult
/usr/share/sendmail-cf/README
examples.
Next, recreate the
/etc/mail/sendmail.cf
Section 11.3.1.3 Common Sendmail Configuration Changes for instructions on doing this.
For more information on LDAP, refer to Chapter 13 Lightweight Directory Access Protocol (LDAP).
11.3.2. Postfix
Originally developed at IBM by security expert and programmer Wietse Venema, Postfix is a
Sendmail-compatible MTA that is designed to be secure, fast, and easy to configure.
To improve security, Postfix uses a modular design, where small processes with limited privileges
are launched by a master daemon. The smaller, less privileged processes perform very specific tasks
related to the various stages of mail delivery and run in a change rooted environment to limit the
effects of attacks.
To configure Postfix to accept network connections from hosts other than the local computer takes
only a few minor changes in its configuration file. Yet for those with more complex needs, Postfix
provides a variety of configuration options, as well as third party add ons that make it a very versatile
and full-featured MTA.
The configuration files for Postfix are human readable and support upward of 250 directives. Unlike
Sendmail, no macro processing is required for changes to take effect and the majority of the most
commonly used options are described in the heavily commented files.
Important
Before using Postfix, the default MTA must be switched from Sendmail to Postfix. Refer to the chapter
called Mail Transport Agent (MTA) Configuration in the Red Hat Enterprise Linux System Administra-
tion Guide for details on how to do this.
11.3.2.1. The Default Postfix Installation
The Postfix executable is
to handle mail delivery.
Postfix stores its configuration files in the
more commonly used files:
— Used for access control, this file specifies which hosts are allowed to connect to Postfix.
•
access
— A configurable list required by the mail protocol.
• aliases
— The global Postfix configuration file. The majority of configuration options are speci-
• main.cf
fied in this file.
— Specifies how Postfix interacts with various processes to accomplish mail delivery.
• master.cf
/usr/sbin/postfix
/etc/postfix/
for detailed LDAP routing configuration instructions and
file by running and restarting Sendmail. Refer to
m4
. This daemon launches all related processes needed
directory. The following is a list of the
Chapter 11. Email