Email is not relevant to a good encryption scheme. You could sign an email, an image you post on Insta, a chat message, anything really.

Thing is, where are the user's credentials stored. In a goverment's computer probably. Greece is taking some steps towards this [1].

A Greek citizen to obtain a digital signature, he has to go to a bank, the bank verifies him, he pays a fee and then the government can accept his digital signature. My guess is that the dictatorship banks established with the Covid excuse might start to bear some fruits finally.

But, people on the internet might want something more advanced, more secure than some COBOL computers storing their identity. Then we save digital certificates and digital identities on the blockchain, making essentially the blockchain the heart of the internet.

When a person from a company sends a message to a client, he can sign the message with his own identity and the identity of the company. Problem solved. No one get's confused when the cryptographic signatures are not verified. The message is invalid and it is redirected to the spam folder.

[1] https://www.gov.gr/en/ipiresies/polites-kai-kathemerinoteta/...