alt Hacker NewsIts not a device/MTA issue, SMTP just is not a secure protocol and there is not much you can do in order to 'secure' human communication. Things like spoofing or social engineering are near impossible to address within SMTP without external systems doing some sort of analysis on the messages or in combination with other protocols like DNS.
SMTP isn't at fault, the social ecosystem is at fault. Every system where identities are cheap has a spam problem. If you think a system has cheap identities and no spam, it probably doesn't have cheap identities — examples are HN or Reddit.