Form not send

The form not send email and I’m getting this email…

You getting this message because an error detected while delivered your email.
For the domain: https://yesweb.it/e-commerce
The log to paste when you open a support issue:
Connection timed out

I used the plugin Post SMTP for test (test ok). My support of Hosting told me the server send emails correctly.
How should I proceed?

Thanks

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