This API is designed to g et rid of fake or bouncing emails. We perform a series of checks:

valid_email_structure
This value is true, if the provided string has a valid email structure

non_disposable
This value is true, if the domain is NOT in in our blacklist of disposable email services

valid_mx_records
This value is true, if the domain has valid MX records set up

smtp_check
This value is true, if the email has a working SMTP Server and emails are accepted for this user.