Why do you think it's a monopoly? I think SMTP is more often on premises at organizations than web services for example.
The hoops to send have existed for a long time and simply evolve. A push protocol without trust is a pretty bad idea after all.. So bad the fax machine needed the legal system to inflict severe punishments for the physical resources consumed by unwanted push (in theory if not practice.)
The hoops to send have existed for a long time and simply evolve. A push protocol without trust is a pretty bad idea after all.. So bad the fax machine needed the legal system to inflict severe punishments for the physical resources consumed by unwanted push (in theory if not practice.)