Incremental Backup of an Outlook PST

[Carl Klouda]

I have been developing a client backup utility for my
company to backup key data off a client's machine (i.e.
My Documents, Cookies, Favorites, etc.)

I am backing the data up to a SQL Server database
using "chunking" via UPDATETEXT, etc.

To cut down on backup time, I log, along with the file
itself, it's last write time so when the next backup is
run, only files that have been changed since the last
backup get backed up again. The one issue I have is the
PST. Many clients have massive (1Gb+) pst's and the last
write time on the PST changes with every e-mail. So, in
the end, the largest amount of time is spent on backing
up the PST.

I was wondering if there was a way to "look" into the PST
and somehow update the initial backup of the PST with
just the changes since the last backup, instead of
backing up the whole PST again. I know commercial
products like Previo can do this. I haven't been able to
figure out how though.

Any help would be great!

Carl