Before sending personal correspondence in a letter, everybody seals the envelope. However, if you happen to send personal correspondence by email, bear in mind that it is sent totally unsealed. It does not take much to read your email as it travels through servers en route to its final recipient. It does not take a hacker, either, to snoop in your emails, a system administrator can do it.
The are several encryption/decryption applications available. However most of them are complex to learn, to configure and to set up. For some of them encryption keys are generated by a third party, which makes configuration even more complex. And even if you are willing to go thru the hassle, are your correspondents willing to do the same?
Maybe you or your correspondents just do not have the time or technical expertise to install huge encryption/decryption applications which might be fine for a bank but are just an overkill of endless dialog windows if you just want to send that personal email to your friend... Or maybe you just don't like the idea that you have to surrender your personal data to a world wide archive of encryption keys (and pay for it as well!) just because you might want to tell your husband that he has overdrawn your bank account.

Crypt is an easy-to-use, lean and mean encryption application, originally designed for very inexperienced computer users. No fancy dialogs, just a "details" window mainly to let the user know that something is actually going on.You write your email, click on "Encrypt and Mail" which opens the email composition window automatically, fill in the address and it's done. To receive and decrypt, click on the attachment. There is no complex installation procedure: the application just needs to be copied in your correspondent's pc. You don't even need to burn a CD. A floppy disk will do.