smtp might be broken, but it would be extremely hard to replace it to something incompatible, as it's a very core of the nowadays internet. Moreover it has the

smtp might be broken, but it would be extremely hard to replace it to something incompatible, as it's a very core of the nowadays internet. Moreover it has the advantage no other popular communication service has: people somehow managed to agree on protocol standard so anyone is able to run own smtp server. In modern days of huge corporations a new popular standard like this seems impossible.