.DBX files are your mail specific files which you get when you import your mails/messages/folders from Outlook Express. They contain your e-mail messages and other e-mail related files that you had in Outlook Express. Unfortunately, it is not possible to directly import .DBX files newer versions of Outlook.
The easiest and most simplest way to import .DBX files would be to download Windows Live Mail first and then import the .DBX files into it. Normally, Windows Live Mail is already installed in newer operating systems, but if you do not have it you can download it free from the Microsoft Website at http://windows.microsoft.com/en-us/windows-live/essentials-other
You’ll need to run through the setup for successfully installing WLM.
Then, once it is installed, you may begin with the import process into Windows Live Mail and then export it from Windows Live Mail in the Microsoft Exchange format.
Further instructions below!
How Do I Import .DBX files into Outlook?
To import DBX files into your Outlook, simply pull down the File Menu and go to Import messages, select the file from where it is saved on your system and proceed with instructions on screen. I have added screen shot, of the export process below which should help with instructions since both the options are accessed from the same menu.
Then once it is imported, pull down the file menu again and select Export Email -> Email Messages and select the (Exchange Format), make sure to remember where you’re saving the exported files. (That’s it).
Now from the Outlook Import Export process menu’s import this file into Outlook.