Zimbra Installation

I have been struggling for the last 24 hours with setup of Zimbra on a VPS environment with 1gb dedicated RAM. In all cases, after the standard installation pains, I was able to get the actual interface up and running just fine. It allows the admin to log in to both admin and the client interface, however no messages can successfully be sent.

I am unaware what the root cause of my problem is at this point, so kindly require further assistance. I am pretty sure there are no conflicts at this point as most all other services have been disabled, as this is a box dedicated for Zimbra, and the standard HTTP has been set to 88. I can access the site just fine at port 88 but sending mail, even to the local admin account that was set up during installation (the only email accont set up on this box) results in an error message after 8 seconds that reads:

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A network error has occurred.
msg - csfe service error
code - NETWORK_ERROR
method - ZmCsfeCommand.prototype.invoke
detail - Empty HTTP response
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From shell, I see that messages are being sent to the administrator, as it notifies me. They read:

From zimbra@cleo.ewebzone.net Wed May 9 06:40:05 2007
Date: Wed, 9 May 2007 06:40:02 -0500
From: root@cleo.ewebzone.net (Cron Daemon)
To: zimbra@cleo.ewebzone.net
Subject: Cron <zimbra@cleo> /opt/zimbra/libexec/zmqueuelog
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/opt/zimbra>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=zimbra>

postqueue: fatal: Queue report unavailable - mail system is down

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From zimbra@cleo.ewebzone.net Wed May 9 06:24:03 2007
Date: Wed, 9 May 2007 06:24:02 -0500
From: root@cleo.ewebzone.net (Cron Daemon)
To: zimbra@cleo.ewebzone.net
Subject: Cron <zimbra@cleo> /opt/zimbra/libexec/zmstatuslog
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/opt/zimbra>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=zimbra>

Could not create the Java virtual machine.

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I do believe tomcat is running and is just fine, however. I am able to access the Zimbra interface just fine, can restart tomcat without error, and see intensive java usage in top (which looks normal).

I am most familiar with CentOS and intended on using this distribution, however had no success. I then switched to Ubuntu install. It appears things installed much smoother, but I'm having the same problem.

A records for cleo.ewebzone.net have bee propertly set, as have a mx record on the authorative DNS server for the root domain, ewebzone.net. The name of my zimbra box is obviously cleo.ewebzone.net.