Sometimes we want to minimize the time required to move all the current mailboxes available on Exchange 2003 / 2007 to Exchange 2010, and for configuring your Exchange 2010 to process high number of mailboxes move simultaneously, we need to change the default configuration, which described as follows:
2. Change the below values:
MaxActiveMovesPerSourceMDB = “25″
MaxActiveMovesPerTargetMDB = “25″
MaxActiveMovesPerTargetServer = “25″
3. Save the file and restart the “Microsoft Exchange Replication” service.