we have setup a small mail server on centos with zimbra. everything went on smoothly. With dns lookups Enabled i am able to send mails and cant receive mails in inbox ( they are differed and but i can see the incoming mails in mail queues) .

if dns lookups is disabled i can receive mails but not able to send the emails.

i am behind a adsl router with broadband connection and port forwarding (NAT) has been done. i have a static ip & all the MX records have been updated . so can one pls help me out . the log shows mail transfer agent unavailable mail gets deffered and i see the origin ip as 127.0.0.1 and origin host as localhost.localdomain.
is it that the mails are not being forwarded from localhost to respective mailboxes.
thanks in advance....