myhostname = node18.linux.class
myorigin = node18.linux.class
disable_dns_lookups = yes
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = node18, node18.linux.class, localhost.linux.class, localhost
mynetworks = 127.0.0.0/8 192.168.5.0/24

/etc/init.d/postfix reload

root:          jerry 
postmaster:    root

newaliases