I’d like to allow recipients of an email to submit a POST request which will have the effect of “liking” something.
It’s clear how you create a GET request in an email (add an href). Is it possible to get (or make the server think it’s received) a POST request?
You can embed a form in your email and set its method to “post”, but you shouldn’t assume that email clients will render forms correctly, or at all. Many email providers like Google, Yahoo and Hotmail will show ugly warnings about submitting data to 3rd parties when you attempt to submit a form inside an email.
A JavaScript solution is less likely to work, so much so that it doesn’t bear discussion.
In short, “yes”, but not at all reliably.