Are you a spy? Up to shady dealings? Maybe you’re just planning a surprise party? Whatever your reason, you can send messages that require the recipient to answer a secret question to ensure that it reaches their eyes only.
To send encrypted messages, sign up for a free account at hushmail.com. Create a username and passphrase (it’s like a password but MUCH longer) and start sending messages. Make sure you check the Encrypt box to compose a secret question and answer. HINT: Make sure the recipient knows the answer to the question!