What if the Recipient cheats? (Score 1)

If the recipient does make a copy of the email (copy by hand into a notebook or take a picture of the screen), his copy becomes the only existing copy of the message. He could then create a "smoking gun" message that you would be hard pressed to deny since the original message is now shredded. Plus, you already look suspicious since you sent the message in self shredding form.

Morals:
Don't send messages that would look bad on the front page of the NY Times.
Consider using PGP to sign all your messages.
Select nude beaches as the venue for setting up those illegal conspiracies.