using LDAP, first get an LDAP server, such as OpenLDAP, running and properly configured.Then edit the /etc/mail/sendmail.mc to include the following:LDAPROUTE_DOMAIN('yourdomain.com')dnl FEATURE('ldap_routing')dnlNoteThis is only for a very basic configuration of Sendmail with LDAP. Theconfiguration can differ greatly from this depending on the implementation ofLDAP, especially when configuring several Sendmail machines to use a commonLDAP server.Consult /usr/share/sendmail-cf/README for detailed LDAP routingconfiguration instructions and examples.Next, recreate the /etc/mail/sendmail.cf file by running m4 and restarting Sendmail. Refer toSection 3.1.3, “Common Sendmail Configuration Changes” for instructions.For more information on LDAP, refer to Chapter 13, Lightweight Directory Access Protocol(LDAP).3.2. PostfixOriginally developed at IBM by security expert and programmer Wietse Venema, Postfix is aSendmail-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 limitedprivileges are launched by a master daemon. The smaller, less privileged processes performvery specific tasks related to the various stages of mail delivery and run in a change rootedenvironment to limit the effects of attacks.Configuring Postfix to accept network connections from hosts other than the local computertakes 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 avery 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 ofthe most commonly used options are described in the heavily commented files.ImportantBefore using Postfix, the default MTA must be switched from Sendmail to Postfix.Chapter 11. Email194
