Is it possible to retract a sent email?

Well unfortunately no there isn't a way to get the email back, once you hit send and it says your message was sent it's gone. So at this point i would do damage control. Call your dad if you can and if you can't reach him leave a voice mail. If you know someone who could possibly know his email pword and account info you could discreetly log into his account delete your one wayward email and be gone. But if that's not possible i would just suck it up and tell your dad the truth. He's an adult obviously he knows you are and you'd be surprised parents tend to be way more understanding than you think. If the email was something ual meant for your partner like dirty talk or something of that nature i'm sure your dad will just delete it and pretend he never saw it and move on. A few years from now you can have a good laugh about it. Now if it was something malicious about your dad there's a tough one, i would just apologize and move on. But yeah once an email is sent its sent, no way of getting it back. Sorry if that's not the answer you wanted, hope everything works out without to much embarrment or hurt.