I found this on zimbra.com website.
Mandriva is one of the leading Linux distributions and there was also a Zimbra Version for Mandriva for a long time. But why was the Mandriva Support dropped? It would be very very nice to see a Mandriva Version again!Operating Systems Available
Zimbra Server is available for many popular operating systems: Red Hat Enterprise, Fedora, Ubuntu, Debian, Mandriva, and SUSE Linux
I think there are many people worldwide who are also using Mandriva based servers.
In our office we have three Mandriva Free Edition based server in a production environment for some years now and they rock!