in /etc/postfix/main.cf configure
myhostname =
inet_interfaces = localhost # so that it won't be open to the world
mydestination = $myhostname, localhost
create a user mailtest on your box
send mails to mailtest@ and read it via mail command or install pine or elm
this should work (not tested, however I have a lot of servers configured with postfix and this should be the minimal configuration you need)
or