Which file extension is used to store Exchange mailbox databases?

• A. .edb
• B. .pst
• C. .mbox
• D. .dbx

Answer: (A)

Exchange stores its mailbox data in a database file created by the Extensible Storage Engine, and that file uses the .edb extension. This .edb file contains the actual mailbox data, including messages, folders, and indexing, and is managed by the server along with its transaction logs. The other extensions represent different mail systems or local client stores: .pst is a personal storage file used by Outlook on the client side, not the server mailbox store; .mbox is used by various Unix/macOS mail applications; .dbx comes from Outlook Express. Therefore, the .edb file is the correct designation for Exchange mailbox databases.