$ sudo apt-get install postfix
			

configure

$ sudo dpkg-reconfigure postfix-config
			

# yum install -y postfix			
			

myhostname = mail.example.com
mydomain = example.com
myorigin = $mydomain
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
#mynetworks = 192.168.0.0/24, 127.0.0.0/8
#relay_domains =
home_mailbox = Maildir/