Yeah, I don't know whats blocking it, there is no way to tell which countries are affected, if that is indeed the reason.
When I try to register I get 'A technical error has occurred'. When entering the site, I get the attached errors.
When clicking the create email button, the console shows this:
POST
https://onereg-account.gmx.com/email-registration 403
I forgot to try this from home, I will try tonight.