sorry for the first post...

well I am behind a firewall, but I am in a DMZ zone where I have everything routed to me.
Since I have an internal address range for the DMZ (192.168.1....) , and I have no internal DNS. I use my ISP's DNS. I think Zimbra is trying to reslove my 192.168.1.120 address and it gets nothing so it can't do a reverse on my address.

is there a awork around without having a DNS internally ? would changing the address of my host in /etc/hosts from 192.168.1.120 to the external one work ?
does postfox takes the address from ifconfig ... I am stuckk.....

Thanks