How does GoodCrypto work when the other person doesn't have it?

Email with people who still don't have privacy software works as it always has. Messages you send them will not be private and so they -- and anyone who intercepts your messages -- can read them just like they did before you installed GoodCrypto.

People with no protection at all will get a note at the bottom of your messages reminding them of the risks of unprotected email. You'll get a note at the bottom of their messages letting you know it wasn't private. That way you always know which messages arrived at your mail server privately, and which didn't. You can also verify which messages arrived and were sent privately.

If a contact is using another PGP product, then you will have to export your key and send it to them so they can send your private messages. And, they will need to send you their key and you import it or import it from a keyserver so you can send private email to them. Don't forget to verify their fingerprint before you rely that you're exchanging private messages.