This has been suggested before, and the same problems are never answered:<p>Email is not guaranteed to be secure in transit. This type of authentication system gaining popularity would <i>greatly</i> increase the incentive for in-transit email scanning.<p>A mailbox is not a password store, and with several &quot;new&quot; mail clients operating with their own server-side component between you and your real mail server, this type of authentication becomes a waiting game of the first major breach.<p>A good password manager will suggest strong random passwords, store them securely <i></i>and<i></i> conveniently, and if you choose, sync them to your other devices.<p>This problem is solved, it&#x27;s just a shame some people insist on repeatedly yelling about how a less reliable, less secure solution is <i>better</i>.