Migrating to Zimbra 5.0GA with minimal downtime?

[mmorse]

zmprov gs server.domain.com | grep zimbraMtaDnsLookupsEnabled

[Miklos Kalman]

I enabled DNS lookups however this is the situation now:

I can send emails from the webmail client, but cannot receive any incoming mail.

I tried two ways:
1/
I added the zimbra server as the SMTP server under Thunderbird and tried using that to send an email to the "dummy zimbra domain". The server complained about a relaying problem eventhough TLS was enabled (attached smtp.out)
2/
I tried using my old webmail from a working domain to send email to the zimbra one and also got an error inside the Message Queue (about deferred emails) (incomming.out)

This is two cases which I would need. The 1/ is to be able to use the new server to send my email nomatter what the sender is (since I authenticate myself via TLS, btw SSL did the same) and 2/ is important to receive emails.

For testing I set up a dummy no-ip domain and set the MX to the dynamic IP of the testing machine. I forwarded the appropriate ports to the internal IP of the VMWare Zimbra image.

What am I doing wrong, there's gotta be a simple explanation.

Thanks,
Miklos