(SMTP) simple mail transport protocol is the TCP/IP mail transport protocol.   under Linux you use the sendmail program.

sendmail configuration are built using the m4 macro language.   The output of the m4 process is the sendmail.cf file.

Location on Linux

  /etc/aliases

  /etc/mail

Format or Syntax

  alias : recipient

where :

alias 

   is the username in the e-mail address part

recipient 

   is the name to which the mail should be delivered

Sample user defined Aliases

  norman.edwards : norm

  edwardsn : norm

  norm : norm@hawk.foobirds.org

sendmail script is found in the /etc/rc.d/init.d/sendmail and the default configuration files are contained in the /usr/share/sendmail-cf/cf directory on the RedHat system.

use the tcpproto.mc file to build a new /usr/share/sendmail-cf/cf configuration file for sendmail services.