Visible feature: not free to send?

This is clearly controversial, but maybe worth thinking about.

Many years ago, when working with some fax-related technology, a customer 
mentioned to me that a big advantage of fax vis-a-vis email was that it was 
_not_ free to the sender.

If we were to take a view that email should not be free for anyone to send 
to anyone, then I think that would fundamentally constrain the technical 
design of any system that conforms to such a goal.  Is freedom to speak, 
for free, at anyone truly a desirable goal in a global network?

The details of what is or is not free can surely range over many 
variations, but my question is directed to the principle, not the detail.

#g


------------
Graham Klyne
For email:
http://www.ninebynine.org/#Contact