Hi Niklas,
Seagate has a product for backing up open Exchange files. It uses ADSM as a 
backup device (through the API).
By the way, I wonder why so many people have the need for backing up open 
Exchange files. We run our backups at night. Users are in bed at that time so 
their machine shouldn't be logged on. If they leave Exchange running no backup 
is made. Bad luck for them if their mailbox gets lost, the most recent backup 
is restored.
Kindest regards,
Eric van Loon