MS Exchange Server 2003 Question:

In Exchange 2003, there is a new feature called the “Recovery Storage Group” (RSG). This is a special instance of ESE (a 5th instance) which can be spun up to provide:
a. Item/Folder/Mailbox level restore without the need for a spare server
b. “Dial tone” (blank mailbox) support if you lose a database and need to get the users quickly up and running for send/receive

To create the RSG, go into Exchange 2003 ESM, right-click on your server object and choose to create a new Recovery Storage Group.
Once the RSG exists, you can add a database to it (any MDB from any Storage Group from any server inside the same Admin Group). Then, use NTBackup or similar to restore a backup into the RSG. Now, you can use ExMerge to extract the data from the RSG and merge it into the production database (for scenario a.), or you can swap the RSG-restored database for the temporary production database (for scenario b).

One of the goals for the Recovery Storage Group