Answer
By default it will truncate your Exchange Server 2003 transaction logs after a completely successful backup.
Details
The product is designed to work very well with Exchange Server 2003 running on Server 2003 (including Small Business Server).
Axcient uses the Volume Shadow Copy Service (VSS) to safely perform hot backups of Exchange databases.
You use Axcient to select the Exchange database files for backup.
Axcient automatically performs the first full backup and then will continually perform incremental backups after that. The product has been engineered for maximum safety by using backward deltas, as opposed to tapes which rely on forward deltas.
As Axcient backs up the Exchange database it will double check the integrity of the data pages in the Exchange database to ensure that they are not corrupt. Thus, you can be sure that once a backup completes it is a good copy of the data.
At the end of a successful backup, Axcient will tell the VSS Exchange writer that a full, successful backup has completed. At this point, Exchange will truncate the transaction logs, because they are no longer neccessary to recover the data. This functionality can be disabled if Axcient needs to work in tandem with other backup programs that might need the transaction logs.