I believe something changed to the mail config of Contact Form 7 v5. I re-installed v4.9 and it worked again (I had the same problem as you).
I have the same problem with (@isaacureta)
See Contact Form 7 5.1.1 – theme needs to properly loads JavaScript in the footer area of each page.
Switch temporarily (nothing will be lost when you switch back) to a WP default theme to see if the problem goes away.
If this fixes the problem & you can’t get your theme fixed, you might try Contact Form 7 – reCaptcha v2. Once installed and configured it offers the same reCaptcha functionality you are used to in previous versions of Contact Form 7.
If using default theme doesn’t stop the error, you could have a general WP email sending problem. See If You Have Email Problems – most people that work carefully through this list of email sending issues are able to solve their particular problems.
the Contact Form 7 still not working
@etos – this is @isaacureta‘s question.
If you are willing to create a new question, which details your issues, somebody will likely be able to help you there.
