SSL stuff: part 1

privacy matters. For those of you who might still ignore it, every single piece of mail that you send or receive, even when you're using an email client like Mozilla Thunderbird or Outlook Express, leaves a copy on the server where your mailbox resides. You cannot avoid this, and deleting the messages in the web interface of an email client does not change anything, as some hidden copies will remain anyway. Google admitted it not so long ago for gmail. They're just honest enough to admit it, but may be not enough when they pretend to do it for backup security reasons. Well, once you've deleted a message from a mail server, you don't expect it to be backed up or do you?
Anyway the only workaround to this privacy mess is called SSL (Secure Sockets Layer), an encryption protocol developed by Netscape to provide enhanced security whenever you connect
to your bank account website for instance, via HTTPS, or when you send mail. For web site SSL, most of the time you'll be automatically using the site certificate, although some sites will require that you authenticate yourself with your own certificate. It's just the same for mails. Once you've subscribed to an email ssl certificate, you'll be able to sign your mails, and as soon as you'll get a mail from someone using a certificate too, you'll be able to encrypt the next message to this person using his public key. And only this person, who authenticated you because you signed your message, will aslo be able to decrypt it. Certificates remain on computers, imported in your email client. Which means that the copy of a message remaining on a web server is perfectly unreadable. Got it?