Ok so Microsoft definitely does not make it easy to backup Outlook Express when you can boot into Windows so when you can not, well that’s when the following comes in handy.
The first thing you will need to do is hook your hard drive up to another computer or perhaps use BartPE to get access to your hard drive. The goal here is to get access to your hard drive files. Outlook Express stores each e-mail folder as a .dbx file. To back up your outlook emails then you need to copy these files to a CD, flash drive, etc.
Outlook Express keeps the .dbx files in a location called Store Folder. By default Store Folder is found in “C:\Documents and Settings\(Your User Name)\Local Settings\Application Data\Identities\{4D2652B7-E489-4302-B4A7-80B37678B194}\Microsoft\Outlook Express”. Make sure to go into your specific user folder as each user’s emails are stored separately. Also the numbers in the folder tree may be different.
Next go to your Store Folder and move the .dbx files to a floppy, CD-R, or other removable medium. Once they are saved on a removable medium then you are good to go.
You may also want to backup your address book which by default can be found at “C:\Documents and Settings\Owner\Application Data\Microsoft\”. Just copy the entire Address Book folder to a removable medium.
You can now go ahead and reload Microsoft Windows or whatever you would like to do.
To restore your saved e-mail, open Outlook Express and select File, New, Folder. Give the new folder the same name as the one you’re restoring (it’s the archived file’s name, minus the .dbx extension), and press Enter. Click the new, empty folder and close Outlook Express. Now copy the archived.dbx file to your Store Folder. If you named the new folder properly, Windows will ask you to confirm that you want to replace the file; click Yes. The next time you reenter Outlook Express, your saved e-mail files will be there.
To restore your address book simply go back to “C:\Documents and Settings\Owner\Application Data\Microsoft\” and paste the address book folder back in. If you changed your login user name you will have to go into the address book folder and rename the .wab file to your new user name.
Hope this helps, let me know in the comments.