Whether using Outlook or Outlook Express, can emails be backed up? Where are they really stored, anyhow? - Jinx
In Oulook Express, the messages are stored in .dbx files - one for each folder, plus an index called folders.dbx - you may have to search for these though, as they are found in different places depending on your Windows version and/or installation.
In Outlook, all the messages (plus the contacts, tasks etc) are stored in a single ‘personal folders’ file with the extension .pst - again, this might be in a different place on different machines. There also might be more than one .pst file on your system (i.e. one created during installation and another one dusring initial configuration) - the droid you’re looking for is usually the larger file with the more recent timestamp.