Don’t want pst available offline

Our laptop users are limited to 200 MB in their exchange
mailbox. If they want to keep any more than that, they
have to put it in a pst. We keep the pst files on their
c drive, and use the personal folder backup add-in for
outlook from microsoft to back them up once every seven
days. However, the offline files (file system, not
outlook) synchronization wants to make these available
offline as temporarily available offline files. I have
tried setting local group policy (files not cached) to
enabled with *.pst listed and I have tried not configured
(which is supposed to block pst files. No matter what
way I set it, it still tries to make them available
offline. Anyone have any ideas?

Jason Bostelman
.