I have many users who have local .pst files that are 500MB is size or
larger and I store a copy of them (.pst's) on a local file server.

Is there a tool, command line or GUI, that I can use that will ONLY
copy the delta changes within the .pst file from the local machine to
the server.  (i.e. 510MB .pst resides on laptop - an older copy of the
.pst (500MB) is stored on the server - I syncronize and transfer only
the 10MB of "changes" within the .pst - now both locations contain the
510MB .pst but the network cost was only a 10MB transfer)

This issue times 100 employees daily - yeah I'm sure you can see why I
need a solution.

P.S. If your wondering why were backing up .pst files to the server and
spending all this time on this issue, don't ask!  I didn't make the
decision, nor agree with it.  But, all of us in IT know that this is
the norm and we have have to make it work.

Please help.