Vote for Outsmart Imbox
Outsmart Imbox extracts messages from mbox files and imports them into specified folders in Exchange mailboxes.
The product is designed for use by system administrators and migration experts, and is supplied in the form of a command-line program that you run in a console window. This design makes it easy to automate via batch files or scripts. Works with Exchange 2000, 2003 and 2007. Requires MAPI to be installed with Exchange 2007.