How could one design a secure and “self-destructing” email?

Question

As most of you know, email is very insecure. Even with a SSL-secured connection between the client and the server that sends an email, the message itself will be in plaintex

Answer 1

IMO, the most practical solution for the situation is using Pidgin IM client with Off-the-Record (no-logging) and pidgin-encrypt (end-to-end assymetric-encryption) together. The message will be destroyed as soon as the chat window is closed, and in emergency, you can just unplug the computer to close the chat window.