The problem with email isn't due to a technical problem with email. It's because:
(1) there exists a messaging system where you can message anyone else in the world without prior contact
and (2) it is an open standard anyone can implement.
So even if you made Email2, it would have the same problems.
People will violate any spec you write and Email2 will not fix that. Encryption isn't a thing because no one cares about it and Email2 will not make people care. The most complex part about email is email authentication (SPF, DKIM, DMARC) and trust but Email2 will still ultimately be have to be based on "how long you've been around" because email is not intrinsically linked to a real identity that has been licensed.
(1) there exists a messaging system where you can message anyone else in the world without prior contact
and (2) it is an open standard anyone can implement.
So even if you made Email2, it would have the same problems.
People will violate any spec you write and Email2 will not fix that. Encryption isn't a thing because no one cares about it and Email2 will not make people care. The most complex part about email is email authentication (SPF, DKIM, DMARC) and trust but Email2 will still ultimately be have to be based on "how long you've been around" because email is not intrinsically linked to a real identity that has been licensed.