If a company owned e-mail, you would probably have to pay for certain messages (if not for all), spam would not exist and you would periodically receive ad messages (if you had not a premium account). Not posible? Now think about the last time you used a toll-road and consider two social networks you are probably using: twitter and Facebook. How many direct messages have you sent today thru them? Aren’t they substitutes of e-mail? Aren’t they owned by private companies?