The Matrix protocol is more or less an open, replicated database. E-mail is similar in some ways, but: 1: it doesn't define enough metadata ("this is an image"

The Matrix protocol is more or less an open, replicated database. E-mail is similar in some ways, but: 1: it doesn't define enough metadata ("this is an image", etc) 2: it doesn't handle backtracking well, if one of the recipient servers misses a message (servers are just supposed to retry a given number of times). 3: it has no security/authentication concept. All of these could be bolted on regular e-mail, but calling it e-mail at that point would be a travesty, and we might as well call that a new protocol. And if we are writing a new protocol, we might as well take a few liberties to address the shortcommings of the first (one could argue against the last part).