Technochic, I haven’t tried this myself — but came across a pretty cool looking Powershell script by Glen Scales that you might be just what you’re looking for.
Here’s a link to the article:
Here’s an excerpt:
“I’ve put together a powershell script that creates a winform that allows you to select what server you want to report on. Then it will run the get-mailboxstatistics cmdlet to retrieve all mailbox sizes for all users on this server you select and populate a ListView with these values. An event is wired to the ListView rows so when you select a row in this ListView (eg a mailbox you want to know where the space is being use). Another function runs that then performs a FindFolder operation via Exchange Web Services on the selected user which will retrieve a list of every folder in the mailbox and the size of that folder. This data is used to populate a datatable which is then used to populate another list view object that will display the names and sizes of those folders in the mailbox.”