Check out Letterbird.
It’s super simple to set up, and much better off-the-shelf styling than the no-CSS options with Formspree.
Sample screenshot:
I tried this and noticed some anomalies with the ‘subscribe’ button using the Dawn and Caspar themes. I contacted Letterbird and they (thanks Matthew!) very quickly identified the problem and fixed the CSS that was an issue. Looks good and is a bit neater than the FormSpree version I also tested.
how did you embed it because when i paste it on the page, nothing happens?
Did you paste it into an HTML card?
Yes, just paste the Javascript into an HTML card, flanked by additional stuff if needed, and “it just works”. I’m a Letterbird subscriber for > 6 months now and happy with the service.