This is called a monopoly. I know people who run their own mail servers to be as independent as possible. Ironically, they show up as spam in Gmail all the time because "This message is similar to messages that were identified as spam in the past." Meanwhile, it's a fucking simple one paragraph message to a programming mailing list. They have to wrestle with DMARK or choose not to as they feel DMARK is playing into the hands of the monopolies giving them too much influence and power over something as simple and fundamental as email.