Learning From the Failure of X.400

X.400, the UN-backed email standard from 1984, was the more feature-rich system by a wide margin — recallable messages, self-destructing mail, built-in encryption, read receipts, delivery guarantees, decades before SMTP got around to bolting most of it on. It lost anyway. The best explanation I&rsquo;ve read for why: X.400 was conceived as a tool, rather than a product. X.400&rsquo;s spec…