A quick heads-up, if anyone is using Google's ReCAPTCHA v1 (the one that presents the visitor with two words / house numbers), it reaches end of life on 31st March and so any forms relying on it will stop functioning.
You should migrate to No CAPTCHA ReCAPTCHA (v2, with the checkbox) or Invisible (which is....erm...invisible).
https://developers.google.com/recaptcha/docs/faq