Here's some background on the existing config:

Zimbra 4.5.11
Single Server
CentOS 4
mail.broadwick.com (only domain, with several aliases)
- icontact.com alias
- intellicontact.com alias
- broadwick.com alias


We've purchased a new server, and we'd like to migrate all users into a new installation of Zimbra 5 on Ubuntu, while migrating the primary domain from mail.broadwick.com --> icontact.com (while still recieving mail for mail.broadwick.com). Once the migration is complete, we'd like to reinstall our old server with Zimbra 5 latest on Ubuntu, and use it as the primary LDAP server for Zimbra.

I was wondering if you guys had any insight on the best way to do this. Thanks!