Here's a typical (no insult intended here) mistake, the FQDN of your server is not domain.com (that is your domain name) but rather it is mail.domain.com and the MX record points to the FQDN of your server and the A record points to the IP your server sits on. The details of what goes in the hosts file is in the Quick Start Installation Guide and has been covered by me and others at great length - it is the same for all of the install platforms of Zimbra.
Originally Posted by carboncow
The hosts file contains the following:
and should contain nothing else.
10.0.0.10 mail.domain.com mail
I've also covered details of how to check your DNS settings and the other necessary configurations for Zimbra many times in these forums.
Instead of telling us what's wrong with Linux (most of which I'd agree with) do tell us what stage you're at and what problems you're actually having and really what it is you don't understand.
I'd prefer it if you'd installed on an RHEL version (CentOS is free compared to RHEL) but that's just a personal preference, I'm assuming that you're installing the OS version of Zimbra and not NE