Due to the General Data Protection Regulation GDPR, we are not allowed to use Capcha in Germany. (Data transfer to a third country)
to keep spam bots away, I would also like to see an addon for a question and answer game during registration-process.
That would completely block unnecessary entries with unverified logins.
For an example, there is a addon for contactform 7 that allows you, to set an ammount of questions with answers. So spammers have to read and understand, what is the right answer before they can send the registration. Its a bit harder that a simple mathe-questionary what you can solve in all languages.
Also it would avoid a mass of unveryfied abonnements.