Sendmail

On the Internet, sendmail is the most popular Unix-based implementation of the Simple Mail Transfer Protocol (SMTP) for transmitting e-mail.

Prerequisite

Make sure that the default SMTP appliction is disabled.

service exim stop
chkconfig exim off

Install Sendmail

yum install sendmail sendmail-cf

Automatic Startup

chkconfig sendmail on

Smarthost

Configuring Smart Host
edit /etc/mail/sendmail.mc

define(`SMART_HOST',`mail.tpgi.com.au')dnl

Compile Config

The new configuration file need to be compiled.

m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

Restart Sendmail

service sendmail restart