Also, if some system accepts such a domain it sill likely it gives it a red flag. I'm using .email domain for a long time, in many cases it's not accepted on r

Also, if some system accepts such a domain it sill likely it gives it a red flag. I'm using .email domain for a long time, in many cases it's not accepted on registration. When it's accepted and it's an e-commerce website then half the time I get an automated email that the sale was either declined, or they require additional proofs. Or, in some cases, the order just gets ignored, and when you physically call them they can't even find the email in their system, so my guess some anti-spam system just blocks it.