Hello everyone,
We are having more and more problems with spam, like probably all Typeform customers. We are therefore urgently seeking a solution that only allows existing emails to be accepted in the forms. 
How can this be done with Typeform or by when can you implement it?

Furthermore, it would be very important that it is easy to define domains from which no emails are accepted (gmail etc.) without having to incorporate complex logic. We only want to accept existing business email addresses and nothing else.

Thanks