@morrow without logs this will be hard to track down. can you ask your administrator to open up a support case for this?
The Zarafa Migration Tool performs a migration by opening each user’s store in the data source (exchange.pst or Scalix db), travesing over the MAPI folder structure migrating each message and folder. This means that all data from the data source will be migrated, including mail, attachments, appointments, tasks, contacts etc. The Zarafa Migration Tool will also check if the message/folder already exists at the destination (a Zarafa Server or a .pst file) to avoid duplicates. The tool will not create users on the Zarafa Collaboration Platform, it assumes that the users to which the administrator wants to migrate data to already exist on the Zarafa Server.
More info can be found in the Zarafa Migrator Manual at