[Kroupware] postfix config

[Jim Philips]

My installation of Kolab went fine. But I can't send mail to other 
users. On the "Servers" page in the Admin interface, I have both host 
and domain set to "localhost" (same as in the documentation). But when I 
try to send e-mail to another user, postfix logs these errors:

Sep 06 19:51:43 localhost <info> postfix/smtp[17619]: E8B18E8A7F: 
to=<irina at localhost.localhost>, orig_to=<irina at localhost>, relay=none, 
delay=2, status=bounced (Name service error for name=localhost.localhost 
type=A: Host not found)
Sep 06 19:51:43 localhost <info> postfix/cleanup[17616]: A55BCE8A81: 
message-id=<20030906235143.A55BCE8A81 at localhost>
Sep 06 19:51:43 localhost <info> postfix/qmgr[17492]: A55BCE8A81: 
from=<>, size=2122, nrcpt=1 (queue active)
Sep 06 19:51:43 localhost <info> postfix/smtp[17619]: A55BCE8A81: 
to=<rebus at localhost.localhost>, orig_to=<rebus at localhost>, relay=none, 
delay=0, status=bounced (Name service error for name=localhost.localhost 
type=A: Host not found)

How can I change my settings so the host and domain will come out correctly?