Sorry WingCo, must read the question.
Emails are stored:
From Vista Mail ...Tools>Options>Advanced>Maintenance>Store Folder for the user that is logged on the computer
eg. C: \Users\WingCommanderFowler\AppData\Local\Microsoft\Windows Mail
It also possible to copy this file to a backup folder so you have a backup copy of your messages. But make sure you copy it into say your documents folder and not a system folder.
Hope this helps.