Email is nowadays the most widespread technology used for personal communication on the net. Alltough it is often not secured for privacy and it is being easily intercepted by all kind of third parties: to enforce governmental control, market surveys and spionage. If you are concerned about privacy then you probably allready heard about the solution to secure email communication: encryption
Encryption is a technique based on mathematical formulas, it can ensure security in your communication by using two keys: a private and a public one, you will give the public to your friends while keep the private one to decypher the messages you receive - everyone wanting to send you a secure message will need to use your public key to encrypt it and only your private key will be able to decrypt it. For more information on its usage and implementation refer to the web pages on http://www.gnupg.org
Dyne:bolic comes equipped with an easy to use email program called Sylpheed which can handle local downloading of mailbox, filters, folders and multiple accounts, while being integrated with the GnuPG encryption system.
Also included is GPA the GNU Privacy Assistant which will help you in the task of generating your encryption keys and handling the collection of your friends keys into a local keyring.
If you are interested into the history of encryption - an hot topic which made USA react with their weapon export regulations to the spreading of such techniques - I suggest you refer to the book "Crypto" by Stephen Levy.