Show HN: Turn form submissions into emails (without the spam)
mailthis.to
mailthis.to
At Formspree we struggle every day against this problem, and it seems very difficult to solve while keeping a simple API.
Also, displaying the email in the action attribute automatically adds your email to spam lists and you're doomed forever (unless you use Gmail, they have pretty good antispam technologies that cannot work outside of their ecosystem). I know you are providing an alias so people do not have to fall into this, but you should be more clear about it instead of saying aloud that your service is spam-free.
I think I misinterpreted your question as "How do you prevent the form API from being used to send unwanted email", not email filtering. We also apply a spam filter to outgoing email requests, but as you stated, it's a challenge to balance that with usability.
Thanks for your feedback!