Or maybe you should try to manually recover the mail? try to do the following:
To resolve this behavior, rename the Pop3uidl.dbx file, and then restart Outlook Express. Follow these steps:
1. Click Exit on the File menu to quit Outlook Express.
2. Click Start, point to Search, and then click For Files or Folders.
3. In the Search for files or folders named box, type Pop3uidl.dbx, and then click Search Now.
4. Under Search Results, right-click the Pop3uidl.dbx file, and then click Rename.
5. Type Pop3uidl.old, and then press ENTER.
6. To start Outlook Express, click Start, point to Programs, and then click Outlook Express.
But if this doesn't help or you're not confident and still decide to use third-party software that there are many different programs and both free and paid,but I as an expert from my experience I can say what I like about OE-Mail Recovery. If it'll help, I'll be very happy.)
http://www.oemailrecovery.com/dbx-extract.html