DBX is a folder file used by popular email client Outlook Express, a standard email client for older versions of Windows operating systems. Standard mail folders are created automatically during program installation process. Users can manually create such folders should they need to do so.

DBX files are helpful in situations where a folder gets corrupted as they allow users to recover lost or corrupted mail and import thme back of Outlook Express folder. DBX data can be imported by other email clients available in newer Windows systems.