How accurate the email verification feature works?

This tool indeed seems to be useful, but how accurate is it actually?

Please note that email verification is 100% accurate. When you enable it in your cards forms, user will click on the "Send Verification Code" which will send a verification code to user. User need to input the verification code in form to validate email.

I would suggest you to please try it out yourself and get back to us if you have any questions.