Failing to send messages

I’ve been trying to make Contact Form 7 works for a month without success. My website theme is Elegance theme. I have installed SMTP plugin and Google reCaptcha v3 and still getting an error with the red border.
I have checked all the fields several times and cannot find any mistakes. I have also contacted the host (GoDaddy) who provided me Premium support and they failed to find the causes.
The form was working fine until I made the decision to change the theme, which didn’t work as expected and had to switch back to the the original theme. Since then the form stopped working.
This is very disappointing and would appreciate any help.
Thanks

The page I need help with: [log in to see the link]