PST = personal folders file. Generally used by Internet Mail users, not
OST = an offline replica of an Exchange mailbox. Linked permenantly to the
mailbox/profile for which it was created - cannot be opened independently.
..pst files are Personal Folders that you can store all your mail files. Its
also the location of your inbox and what nots and is stored on your local
harddrive. The .ost files is your off line folder if your using a exchange
server. It works and looks like your mailbox when your not connected to your