Do you have any information regarding utilities that can compress the Exchange mailbox online? I know how to do it with eseutil, but I am looking for an application that can do it online.
As far as I know, compaction of an Exchange database can only happen when the database is offline. There is a maintenance routine that Exchange runs against the information store databases each night, but that process does not compact the database.
I'm not aware of any tools out there that can do this, and I strongly suspect that if you find one, it will not be supported by Microsoft.