We intend to migrate from Exchange 2000 onto the latest stable release of Zimbra. Our migration strategy consists of phases where users in the same domain will be split across Zimbra and Exchange. Eventually, all users and domains will be on Zimbra.
Reading some documentation, I have found that we must create mailboxes on Zimbra for all users, even those that are hosted on Exchange still. Is this true or is there a better way of doing this? We have lots of users so this will take a long time to complete and what happens when we migrate users from Exchange to Zimbra that had formerly had a rule to route mail to Exchange for their mailboxes?