Connection refused to MTA
<Please disregard this post. I would like to delete it, but the edit mode offers no delete option that I can see.>
I'm administrating a production ZCS installation running Open Source version 4.0.4 under Fedora Core 4. Zimbra has been running successfully for over 4 months but suddenly now all messages are stuck in the Deferred queue. The stuck messages all show "Reason: connection refused". Additionally, in the "server status" window in the admin interface, I have a red X in front of the server name, and also in-front of the antivirus service. I'm still able to send mail from Zimbra, so SMTP is working. But the mta has suddenly stopped receiving all mail. "Enable DNS lookups" has always remained checked. The mail server is DNS-connected and can ping remote IP's and resolve domain names. The MX records are accurate in nslookup. I've checked the logs, but don't know enough about what they're stating to properly diagnose the problem. This is a real mystery since the mail server has been stable ever since installation, and no major change was recently made. If anyone can help me diagnose this problem as soon as possible, I'd greatly appreciate it. Just ask me to post the appropriate log file, and I'll paste the contents. Or, if you have a quick suggestion about how to resolve this mess, all the better! Thanks.