sudo aptitude install postfix
hostname -f


# sudo vim /etc/postfix/main.cf
myhostname = example.com
myorigin = example.com
mydestination = example1.com, example2.com, ...
virtual_alias_maps = hash:/etc/postfix/virtual

# sudo vim /etc/postfix/virtual
@example1.com    name@forward.com
@example2.com    name@forward.com


sudo postmap /etc/postfix/virtual
sudo /etc/init.d/postfix reload