postfix: mail forwarding for domain if user unknown

[Thomas Nintemann]

Hello,
I have a maildomain "example.org" and some users on different kolab-systems at 
different places. The kolab systems, call them place-1 and place-2, have all 
the same maildomain "example.com".
They do fetchmail mails from Internet and have a ISP as smarthost for relay.

My question is:
It is possible to configure postfix under kolab so that mails 
for "user2 at example.com", that the kolab-system on place-1 does not now, will 
automatically be forwarded do the kolab-system on place-2?

Thanks

Thomas