Each folder that you see in the Outlook Express Folder list is stored on your hard disk as a single file with the same name as the folder but with the extension DBX added at the end, such as "Inbox.dbx" and "Sent Items.dbx". All these DBX files are stored in a single Windows folder called, not surprisingly, the Store Folder.
The Store Folder is usually located deep within the Documents and Settings folder in Windows 2000 and Windows XP, and is by default marked as a hidden folder. This makes it tricky to find your Store Folder in Windows Explorer, but there is a very good reason for this. One source of DBX corruption is trying to open and edit a DBX file yourself.
Avoid the temptation of clicking on a DBX file to see what it contains. It is enough to know that a message inside a DBX is not simply a string of text that you can read, but rather is broken up into parts which are not assembled into a legible message until you access the corresponding folder in Outlook Express.
Also realise that altering even a single byte in a DBX file might render the file completely unusable by Outlook Express.

The following is a quick and easy way to display your Store Folder with just a few clicks and keystrokes.

1. In Outlook Express, click Options on the Tools menu.
2. Click the Maintenance tab.
3. Click the Store folder button.
4. Press the TAB key to highlight the Store Folder path.
5. Press CTRL+C to copy the path to the clipboard.
6. Click OK, then again OK to close the Options panel.
7. Click Start, and then click Run.
8. Press CTRL+V to paste the path into the command line.
9. Click OK.
10. If you do not see any files in the folder that opens, click Folder Options on the Tools menu, click the View tab, and then click "Show hidden files and folders" and click OK.

In Windows XP, the Outlook Express user files, including *.wab and *.dbx files, are by default marked as hidden. To view these files in Explorer, you must enable Show Hidden Files and Folders under

1. Start and Control Panel
2. Folder Options click View.To determine the location of your OE WAB file,
   • If there is no path shown, that means you have set OE to share the Contacts folder in Outlook and so no *.wab file is used).
   • If you open the *.wab's folder in Windows Explorer, you will see not only the username.wab file but also an automatic backup copy named .wa~ or usernamewab~.

With the presence of hidden folders it sometimes happens that duplicate contacts end up being stored in the WAB. This is not really a serious problem, but it can be confusing to type in a name in a new message, only to be presented a dialogue asking to choose between 2 identical contacts.

To view all contacts in all folders, regardless of which Identity is currently logged on, click Start| Run and type wab /a. If needed, click View| Folders and Groups to see the folders.
You can now find any duplicates and move them to the Shared Contacts folder, rather than in each Identity's folder.