Validate email

Hi,

I need the form to check the email.

I created 2 cells where the user enters his email twice, this is to avoid typing errors.

Another solution also the best, which sends an email to the sender and must click on the link to validate it.

On the web I found this page https://contactform7.com/2015/03/28/custom-validation/ I entered the code in the functions.php file, but it doesn’t work

Thanks