Have multiple domains running on a single OE server. About half a dozen of mine and three for a fried. His need/use has outgrown my server (and bandwidth) so I want to split off his domain(s) to a separate server that I have setup with bare OS and Zimbra (same version, 4.5, as my existing server). The new server will move over onto his network (and his bandwidth) and become totally separate.

How do I go about migrating a domain and, if possible, preserve everything
user accounts (settings, email, contacts, folders, tags, etc),
domain settings,
spam training (don't know if this makes sense),
documents (nice to have but only marginally used thus far)

In an ideal world users wouldn't even know the difference except they will use a different url.

Any help, appreciated.