With S/MIME, you first send each other a signed message which piggybacks your public key. From then on you can exchange encrypted messages. With PGP, there are key registries where you can get people’s keys, so you can send encrypted mail even to a total stranger whom has never written you before. With PGP there is no central certificate issuing authority to check everyone’s credentials. You only know that someone’s key really is theirs’s because someone you trust or someone, whom someone you trust, trusts, said it was, in a web of trust.

Unfortunately, Eudora does not support S/MIME though there are plug-ins available from third parties, e.g. Cryptigo: Eudora S/MIME plugin for $20.00 USD .

You can acquire two classes of digital ids to use with S/MIME. A first class id, sometimes called a personal email id, attests that indeed a real person of that name has possession of the signing key. A second class id just attests that the holder of the signing key once received mail at the return email address. You can get one of these free.

To sign or encrypt an email, you must enter a passphrase. This stops your children from sending signed mail in your name using your digital id certificate stored in the email program of your computer then you are not looking.