in the envelope I recommend that MAIL FROM:<> be used. a lot of
MTAs reject it these days, but they are clearly broken.
I agree that it is wrong to reject null return paths altogether.
However
your suggestion is incompatible with backscatter detection systems
(such
as BATV or Signed Envelope Sender) which assume that null return paths
are
only used for bounce messages.
those systems are operating on false assumptions. it's never been the
case that <> was limited to bounce messages.
This idea of obfuscating the message header does not provide proper
anonymity, since the trace fields will still contain the IP address of
the
sender which is enough to identify them. Why isn't pseudonimity enough?
Why not propose a specification for properly strong anonymity based on
mixmaster or some other multi-stage cryptographic system?
I don't view this as trying to provide true anonymity, in the sense
that the message cannot be traced. I view it as trying to provide a way
to say "we don't know who actually sent this message, or whether he
even has an email address".
Keith