I did a test install of Zimbra on Ubuntu 8.04 and I used my registered domain name for the FQDN. I followed the install guide for Ubuntu 8.04 and everything worked after testing it out.
The only problem was instead of having "mydomain.com" as the address, it became "hostname.mydomain.com". When I sent myself an email, it showed up as "email@example.com".
How would I avoid this when I install Zimbra on a production server?
I recall during the install there was a part about creating a new domain or something like that. I selected no, since I already have this domain registered, I figured there wasn't a need to.