We have some rather large Outlook PST files left over from previous employees. Some of these are connected to Outlook (2003 and 2007) accounts in the enterprise, and seem to be getting flagged for backup even though the contents don't change (as far as I can tell, anyway.)

Now I *could* just *ask* each user on the network whether they are doing this, or I could find out somehow through the network. If I wanted to do the latter, how would I get it done?