[Plugin: Jetpack contact form] "Page Not Found" error when submitted

My client’s site: mrkleannj.com

Using JetPack’s content form creator, I put a contact form in a widget on the landing page, and a contact for on the Contact page (main content is also a widget). The theme is a child theme of Builder from iThemes.

The Jetpack contact form generated this code:

[contact-form to='tim@mrkleannj.com' subject='Quote Request from Web Site'][contact-field label='Name' type='name' required='1'/][contact-field label='Phone' type='text' required='1'/][contact-field label='Email' type='email' required='1'/][contact-field label='Comment' type='textarea' required='1'/][/contact-form]

Here’s the issue: When a user clicks “Submit,” no email is sent, and user is directed to a “Page not found” error message.

Have researched and cannot find a solution. Your feedback greatly appreciated!