Hi there,
i tested the form – and the form submission worked. So it doesn’t look to be a problem with the form itself – most likely an SMTP issue.
Happy Forms provides this troubleshooting guides under point 7 regarding SPAM email or SMTP Setup:
https://happyforms.io/help-guide
Regarding SMTP you should check with your host if there are any protocols blocking the email your sending it to – a common issue is if the email address you’re using is different tot the website domain.