Here an easier option for those concerned with privacy of their users. 1) Validate the email address first on your side (using regex). 2) Then send the domain n

Here an easier option for those concerned with privacy of their users. 1) Validate the email address first on your side (using regex). 2) Then send the domain name part to the service for validating and correction. Maybe append a fake username before the @. So if a user enters someone@yahoo.cm , I validate it first then send someotherperson@yahoo.cm to the the mailgun. Now your real user is protected. Now you don't send them the real user name but get most of the benefits.