Try this utility (for free):
http://www.softlakecity.com/
has worked out for the same problem couple of times already.
Milan
Justin wrote:
Hi,
My Sent Mail Items has reach 2GB Limit and I have move some mails to another
folder. Then I choose to compress the Sent Mail Items Folder. However, most
of my e-mail lost after the compression. I wonder what happens to my
mails?Thank you.
Almost forgot, during the compression, a warning message like "outlook
express is using the file" has prompted on the screen.