Trouble sending emails

[rocktech]

I am getting myself well acquainted with ZCS. Which I have to say, I REALLY like. Except for the whole can't send email issues. I can receive them from the outside world, but nothing makes it past the MTA for outgoing mail.

Using the Web Mail Client, I get the following error message the FIRST time I hit send:

try again: unable to connect to the MTA.

If I hit send a SECOND time, I get this message:

system failure: Unable to get SMTP session for...

The zimbra.log shows no errors/failures/issues that I can recognize. The nmap shows smtp assigned to port 25.

Dig shows this:

zimbra@rt1:~$ dig rocktechonline.com mx

; <<>> DiG 9.4.2-P2.1 <<>> rocktechonline.com mx
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43924
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;rocktechonline.com.            IN      MX

;; AUTHORITY SECTION:
rocktechonline.com.     3600    IN      SOA     dns.stabletransit.com. ipadmin.stabletransit.com. 1274384627 3600 300 1814400 300

;; Query time: 25 msec
;; SERVER: 173.203.4.8#53(173.203.4.8)
;; WHEN: Fri May 21 05:45:17 2010
;; MSG SIZE  rcvd: 98

The version of ZCS: Release 6.0.6_GA_2330.UBUNTU8_64 UBUNTU8_64 FOSS edition.

I've attempted to change the MTA global settings to use various hosts as defined on the system. The original value I had was set to "rt1". Here's the contents of my /etc/hosts file:

127.0.0.1     localhost localhost.localdomain
173.203.82.203 rt1.rocktechonline.com   rt1

Any thoughts? It feels like I'm doing something terminally stupid.

Thanks for the help!

[phoenix]

According to the dig repsonse you have no valid MX record, you need an A & MX record pointing to the Zimbra server. If you're behind a NAT router you'll need a Split DNS set-up.