Dave Crocker wrote:
mail from does not scale all that well. Imagine having to preregister
every telephone you might call from.
That's actually quite different.
RMX mechanisms require registering the MTA. That's equivalent to having
to pre-register the physical telephones that you will use.
No, I think it's much closer to preregistering a small, fixed set of
operators who are willing to relay your call. That would include those of
your personal service provider, who you can connect to with the use of your
card from any phone that takes it.
Registering the MAC address of each computer you will use to send mail is
equivalent to registering the telephone.
All this talk of analogies between the email system and any other system,
for communication or anything else, does nothing to advance this discussion.
People here are using analogies to create an image of the costs and benefits
that differs greatly from those seen in email and the proposals on the
table. Therefore, I suggest that we stop using analogies between the email
system (with or without changes) and other systems entirely, and provide
hard statements of facts, assumptions, and beliefs.