hi..i guess is you trying to "test" the system as LOCAL and your domains and stuff is either in HOSTS file and have NO DNS
from other messages in fourm:
"Is there not a way to tell Postfix that if the mail is for local delivery that it should just hand it off to the local delivery engine and not do a DNS lookup to find the mailserver?.."
if above is your problem:
# Log to Zimbra Admin
# go to Global Settings
# Under MTS "un-check" DNS lookup's
# Save
then log to Linux box
> su - zimbra
> zmcontrol stop
> zmcontrol start
if you see all services runnig and no error then you should be able to send mail to local domain and you will see mail in inbox BUT you wont be able to send mail OUTSIDE or to any domains which is not in your HOSTS file..but this will let you TEST your TEST setup
..hope this helps
Raj S Vrach