Can't send emails out

I just installed Zimbra on FC4, no firewall. But I can't send any emails out from Zimbra server.
I can't telnet to any email server's port 25 from the Zimbra server, but can do it from other hosts in the same network.
It must be something in the Zimbra server simply block outbound port 25 traffic. Does anyone has similar experience?
Any help is highly appreciated!!


Here is the console output from Zimbra server:

[root@mail mail]# host -t MX gmail.com
gmail.com mail is handled by 10 alt1.gmail-smtp-in.l.google.com.
gmail.com mail is handled by 10 alt2.gmail-smtp-in.l.google.com.
gmail.com mail is handled by 50 gsmtp163.google.com.
gmail.com mail is handled by 50 gsmtp183.google.com.
gmail.com mail is handled by 5 gmail-smtp-in.l.google.com.
[root@mail mail]# telnet gmail-smtp-in.l.google.com 25
Trying 64.233.163.114...

When try to run "telnet gmail-smtp-in.l.google.com 25" in another PC, I got the response right away.

Here is the output of postqueue, does this mean postfix is down?

[root@mail mail]# postqueue -p
postqueue: warning: Mail system is down -- accessing queue directly
Mail queue is empty

But when I tried to telnet to the Zimbra server port 25, I got reply:

220 mail.server.com ESMTP Postfix

Zimbra doesn't block any outbound port 25, do you have SELinux installed or activated? Did the Zimbra server install OK? Do you have postfix disabled on this system?

Sounds like it is not something to do with the Zimbra.
SELinux is installed by default, but I have disabled it by runnning "set enforcement=0". Also I can telnet 127.0.0.1 25, please see the output here:
[root@mail ~]# telnet 127.0.0.1 25
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
220 mail.server.com ESMTP Postfix
quit
221 Bye
Connection closed by foreign host..

Any ideas?

Thanks!

Try resolving the IP addresses of those remote mail servers from the zimbra box - is that working? Try telnetting by IP - is that working? Try traceroute - does that work.

Remember - troubleshooting is about reducing variables.

It didn't work neither by IP or by hostname. Tracewoute no problem.
I just tested with one email server, could telnet to port 80, but not 25, but from an XP PC DOS prompt I could telnet to both ports.

This is probably your ISP, but you may have a weird firewall setup on your linux server (but zimbra isn't blocking outbound anything).

iptables -t nat -L
iptables -L

What do those two commands return? (You'll need to be root).

Firewall is wide opened, please see below:

[root@mail ~]# iptables -t nat -L
Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Chain POSTROUTING (policy ACCEPT)
target prot opt source destination

Chain PREROUTING (policy ACCEPT)
target prot opt source destination
[root@mail ~]# iptables -L
Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Chain RH-Firewall-1-INPUT (0 references)
target prot opt source destination
[root@mail ~]#

If you can traceroute to remote hosts, but can't get there on port 25, and it's not being blocked by the server's firewall, it's being blocked somewhere else. Any intervening firewalls before you hit the internet? What kind of connection are you on (dedicated, dsl, cable, etc?)