Where does Windows Live Mail store messages?
WLMail stores all messages as individual files in your personal message store. This message store is known as the Store Folder and contains a number of folders, many of which contain messages, and a number of other files. One of the folders in the Store Folder is called Storage Folders, so called because it is used to store some of the folders containing messages. Storage Folders are accessible in WLMail if enabled by clicking the Storage Folders button on the View tab or pressing Alt V L F (repeating the process disables).
One of the files in the message store is called Mail.MSMessageStore. This file stores no messages – messages are stored as individual files in folders within the message store folder.