Sorry, I was on my way out the door. I'm not suggesting taking away your freedom. I'm not actually for the idea. I just don't something like email "SHOULD" be free.
You could, for instance, have Email2 where you had to pay "someone" to send it. If you had an Email2 address, you could only receive from Email2 senders. And Email2 senders have to pay "someone".
Also, "free" and "freedom" are two very different things.