I have successfully used the newsletter_subscription_extra filter to add a recaptcha box to the subscription widget, however, I can’t find a way of validating the recaptcha. Is there a filter or action for checking the form data and returning an error as necessary?
Thanks Stefano but I’m not sure how that would help me validate the Google Recaptcha?
I have found a solution, for now, using JS. I can change the form action attribute on page load and when the recaptcha is checked a callback will then set the action attribute correctly for the form to submit.