A firewall hardware between internet and Lan, I set forward DNS address on internal DNS server, and gateway address 192.168.0.1 also on the DNS server, in Zimbra Admin UI, I tick the look up for DNS optoin on, leave MTA relay as blank.
Now the problem is : I sent email to @hotmail.com, @sina.com...etc. all email to internet were deferred in the deferred queue.
In the error column of Summary/Filter, when I move mouse on one item. it shows "Connect to mx4.hotmail.com [18.104.22.168] network is unreachable. Why the DNS can translate host name to ip, but network is unreachable? anything wrong with my configuration? By the way, The sever OS is OpenSuse10.2
Many Thanks in advance!