When trying to migrate user data from Exchange 2003 to Zimbra 4.5.6 i get the following error message:

27-07-2007 16:02:56 [160]: Opening other users store
27-07-2007 16:02:56 [160]: Logging on to zimbra server (
27-07-2007 16:02:56 [160]: RPC Error: The server name could not be resolved.
27-07-2007 16:02:56 [160]: Too many mailboxes failed, exiting
27-07-2007 16:02:56 [160]: Worker thread exiting

Which server name could not be resolved? I must admit that I have not created any DNS records yet for the zimbra server, but is this a problem for the migration wizard? When configuring the Migration Wizard I only used IP addresses and no hostnames. Is it possible that the domain to which the accounts get migrated already has to resolve to the IP address of the zimbra server?

And by the way, the client on which the wizard is run can connect without any problems to the Exchange server.