You can't embed a form into an email as most email service providers won't support iframe content which is required for embedding our forms.
A great workaround, however, is to include the first question of a form as an image in the email and then link it to the form. So when the submitter answers, they are directed to the form.
You can always share a link to your form as well. You can get the link to your form under the "Share" menu in the form editor.