Hello Jay!

 AA>> Outlook 2007 here.  But it definitely stops at 2GB.
 AA>> Apparently, the system allows different types of .pst.
 AA>> Mine is "Personal Folders File (97-2002)".

 JH> I wonder if it's as simple as creating a new .PST in Office
 JH> 2007 and then dragging & dropping the folders into the new
 JH> .PST?

The actual built-in help for Outlook 2007 does not describe the  
increased 20GB support.  But I found a post that described a  
simple process to convert.

You were correct. I just needed to create a new core .pst file.   
Then it was a simple matter to copy the old "Inbox" and drop it  
into the new one.  All the subdirectories went along for the  
ride.  The process took about 12 minutes to copy 1.3GB.

Curiously enough, the new file was even smaller than the  
previous compacted one:

Directory of C:\OUTLOOK Data

09/04/2021  02:23 PM  1,351,549,952 august.pst <= in OLD format.
09/04/2021  02:21 PM  1,032,840,192 august2.pst <= in NEW format.



--
  ../|ug

--- OpenXP 5.0.49