What Manoj/Ben did to make postfix work on on a DHCP box:

cd /etc/postfix

edit main.cf:

   make sure 'inet_interfaces = localhost' was set
   set 'sender_canonical_maps = hash:$config_directory/sender_canonical'

created /etc/postfix/sender_canonical, which contains only:

   sussman sussman@collab.net

Compile to db by running '/usr/sbin/postmap sender_canonical'.

/usr/sbin/postfix/restart.


... and now, any outbound mail from 'sussman' has the envelope
magically rewritten into 'sussman@collab.net'.  No need for the box to
"pretend" to be collab.net at all.