This is what I was thinking as well. An account isn't even necessary, just have a two step process on Formspree. 1. Enter your e-mail address. Click next. 2.

This is what I was thinking as well. An account isn't even necessary, just have a two step process on Formspree. 1. Enter your e-mail address. Click next. 2. Copy the generated code, //api.formspree.com/Kn2JanlPkZ into your form as the action. Obviously this code and e-mail combination is then stored in the Formspree database.