DMARC does a decent job of solving a few of those points. Alas, that only proves the point that another commenter made about server-to-server SMTP being a hack-

DMARC does a decent job of solving a few of those points. Alas, that only proves the point that another commenter made about server-to-server SMTP being a hack-job piled on top of another hack job. The one thing DKIM is good at is for protecting the From-header and body from modification, allowing receiving servers to verify that the sender is genuine whenever they receive an incoming message (when combined with DMARC that is). For anything else, use PGP, S/MIME, or something else that actually does end-to-end encryption/signing.