well, you can use cyradmin to take a look at the other shared folders on the server side without changing anything. i'm going to guess that's the way the shared folder was setup in the first place.
of course, this begs the question: why does this client/company share 45 gb of sent mail in this fashion, and how could they better use technology and/or resources for their needs?
it sounds like yet another gross misuse of mail standards. just because you
can share that huge pile of mail data doesn't mean you
should.