Understanding the PST file
Personal Folder Files are part of several Microsoft applications, including Outlook, Outlook Express, Windows Messaging, and Microsoft Exchange. These applications use this file, extension .pst (Personal Storage Table), as the equivalent to the ever popular junk drawer. This means that any item in your Outlook email, from calendar notations to copies of sent emails, gets tossed into this file for quick storage.
In software dated before 2003, the .pst file had a set space limit of 2GB. From 2003 on, the space limit of the file is user defined, and can be set as high as 33TB (Tebibytes). As it applies to Microsoft Exchange, the .pst file is stored on the server at hand. When a user does not have an Exchange email account, the file is then stored on the user’s computer. Beginning in 1997, Personal Folder files were encoded using the ANSI (American National Standards Institute) format. With the introduction of the 2003 versions, however, Microsoft began using Unicode for file formatting to increase international usability.
If a .pst file becomes corrupted for any reason, the contents-including important emails from clients, contact lists, or calendar events-are rendered inaccessible. For older versions, Microsoft provided several service packs in hopes of preventing such a loss; however the fixes are of very limited use. Therefore, since the contents of your .pst file are definitely not junk, backup of Outlook, or any of the other Microsoft applications that utilize this file, is critical, and the only true way to preserve your vital information, as well as your sanity.
