Same issue, with a twist

[responding]

I am new to Zimbra, and worse yet, new to Linux, and have been trying to solve an issue for serveral days now. While I've been searching forums and have encountered many similar issues, I have found none that exactly represent mine, nor have I been able to solve it, so hope someone with more experiance can help me.
Did a clean install of Centos 4.4
Running Windows2003 DNS
Created MX record with mail.xxx.com
Created a Host record where mail.xxx.com points to the (private)IP of the Zimbra box
Natted port 25 and 110 to (private)IP of zimbra box
Did a clean install of Zimbra 4.5
Zimbra fails to find an MX record for mail.xxx.com
Continued install (after trying to fix and being unable)
Zimbra runs perfectly, and I can send internal mail no problem...
I can receive mail from third party services (ie...hotmail, gmail, etc)
When I attempt to send, mail is deferred, with an error of "no route to host", or "connection timed out".
I would greatly appreciate any help I can get. I am under alot of pressure to have this up and running soon. I'm pretty thrilled about it too...It looks awsome! Thanks in advance

[jholder]

Zimbra fails to find an MX record for mail.xxx.com

Let's try one thing at a time

You need to make sure that first in the DNS search order is your AD box.

-john

[responding]

Thank you again. I'll gladly do whatever it takes. When I did the install of Centos 4.4, I pointed the dns servers as follows:
192.xxx.xxx.10 (Primary DNS)
192.xxx.xxx.13 (Backup DNS)
192.xxx.xxx.254 (PFSense Firewall/Router, which forwards to ISP's DNS)
When I run a "dig -t xxx.com" from the Zimbra box, it resolves an MX record, and A record for the mail server, both of which are correct, and are resolved on my AD box. Not sure how to check the search order directly, but this does tell me that i'm resolving on my local dns right?

[responding]

add:
The mx record that resolves points to my internal (private) IP on the Zimbra box... Is this right, or should it point to my external (public) IP and be natted back in?

[MidSpeck]

add:
The mx record that resolves points to my internal (private) IP on the Zimbra box... Is this right, or should it point to my external (public) IP and be natted back in?

For external clients (such as Hotmail) when they resolve your MX record, they will need to see your external/public IP.

Internally on your Zimbra machine, I believe that it can resolve either IP and be fine... as long as it knows that mail meant for itself (internal to the domain) just stays.

It sounds like the problem is that it doesn't know how to send mail out to other hosts ("No route to host"). Try a few things here:
First, on your Zimbra host, run:

dig MX hotmail.com

For me, it returns mx1.hotmail.com through mx4.hotmail.com as possible mail exchangers for the domain hotmail.com.
If that works out, try:

telnet mx1.hotmail.com 25

Which will connect to port 25 of mx1.hotmail.com. It should respond and say something like:

220 bay0-mc10-f14.bay0.hotmail.com ........

You can just type in QUIT to disconnect from their server.

Your mail server will in essense do the same thing when it tries to send mail to an external server. It'll look up the mail exchanger (MX) records for the server and then connect to the SMTP port (25) and try and send the mail.

So, if you can do both of those manually from your Zimbra host, Zimbra should be able to do them as well. Otherwise, we have another problem. Hope this helps.

[responding]

I haven't been back here in a week or so, but just wanted to close this one as resolved. In case anyone else has the same issue, for some reason my ISP was blocking port 25. Wasn't supposed to be, and and it was a little difficult to get them to check, but once they did, they opened it up and zimbra has done nothing but impress me since. Thanks to all who helped me!