Thank you guys for the replies.
As I mentioned above that my log is not working, I was able to find out that under Fedora 8 the logger should rsyslog not syslog, after fiddling for a few days I finally got it to log.
Back to my main prob. As per Bill, I was thinking in the same line, that its not a firewall issue. But thats the only thing I did that caused the mails to get stuck in que. After re-doing the same 3 times (activating and deactivating the firewall) It suddenly worked with not problems.
Next question is, how robust would my system be, facing the net with public IP with just the linux firewall to defend it? should another router/firewall be necessary?
Are there other ways to harden zimbra?
Again thanks guys