Hi,
To my knowledge it's enough to have a consistent (done with Scalix shut down or if doing LVM snapshots Scalix write activity suspended), all-permissions-in-place, backup of the /var/opt/scalix directory contents to be able to build a similar server with all the data intact.
But your need may be different, if you need quick-to-restore backups of the user data also, you should run smboxexp in cron for all users/desired users only (as mentioned by Shredder above). If you want the whole server (OS included) backed up, you will need to use more sophisticated (a.k.a. complicated

solutions from 3rd party vendors.
BR;
Kimmo