Outlook Compression and Encryption of PST files

While Microsoft has already launched Office 2007, the complete revision of how a traditional Office Suite would look like, I am hesitating to make that change. Microsoft Outlook 2003, one of the most useful applications in Microsoft Office, stores its email in a file with .pst extension. There is a special feature within Outlook 2003 (and also previous versions of Outlook) that allows user to select the compression or encryption level.

Basically, there are three level of encryption:

none
compressible
high encryption

(find out more about the encryption or compression feature in Outlook 2003)

Understanding Microsoft Outlook 2003 Encryption

No Encryption
As the definition suggests, the email will be stored in a way such that anyone who has access to your .pst file will be able to view your email using a simple text editor, such as Notepad. Anything in HTML will be easily visible.
Compressible Encryption
This option provide simple encryption to the .pst data, such that any simple text editors will view the data as garbage. However, this is not always foolsproof, as there are some hacker's tool available in the Internet that could decrypt your data.

Although this option provides compression the data, it is not as good as those used by other compression applications, e.g. WinZip or WinRAR.
High Encryption
A stronger form of encryptography is applied in this method, ensuring hacking the .pst data is much more difficult. However, the trade-off is that it will take longer time for Outlook to read and write on these file.

It was noted that compression is still possible for this encryption methodology but there is almost minimal gain.

Recommendation
It is fairly simple to know what you need by now. If you do not mind if your data confidentiality is being compromised, then choose No Encryption. Furthermore, it definitely gives better compression when used with a third-party compression software. If you have extremely sensitive data, it is best to set the option to High Encryption.

However, if you are still unsure, leave it at the default option of Compressible Encryption.