Postfix Configuration

1) Main commands are
postalias: Postfix alias databases. This is the program behind the newaliases command
postfix : starting and stopping the mail system, and for some other administrative operations
postcat : displays the contents of Postfix queue files
postconf : displays Postfix main.cf parameters
postdrop : mail posting agent run by the sendmail on systems having no world-writable maildrop queue directory
postkick : makes some internal communication channels available for use in, for example, shell scripts
postlock : provides Postfix-compatible mailbox locking for use in, for example, shell scripts
postlog : provides Postfix-compatible logging for shell scripts
postmap : maintains Postfix lookup tables such as canonical, virtual and others
postsuper: command maintains the Postfix queue

2) Main config file for postfix are
main.cf - This is the main as the name suggests
master.cf - This controls the daemon process

3) Postfix is a MTA which uses SMTP to transfer mails. So enable SMTP in firewall.

4) The main configuration is main.cf. Here see to it at least these are proper

alias_database = hash:/etc/aliases
inet_interfaces = all
mydomain = index.com
mynetworks = 127.0.0.0/8, 192.168.0.0/24
myorigin = $mydomain
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
relay_domains = $mydestination

5) Now try to send mail using mail program. It should work properly.