There isn't such a layer for email that is widespread (there's certified email in Italy). PGP and S/MIME crucially lack time and validity stapling. In a lot of

There isn't such a layer for email that is widespread (there's certified email in Italy). PGP and S/MIME crucially lack time and validity stapling. In a lot of EU countries you can however digitally sign a container and mail that (under eIDAS those qualifying electronic signatures are legally binding, unlike random publicly trusted S/MIME signature). But I guess if your alternative is fax, then a lot of thimngs are better than that.