Mark E. Mallett wrote:
| In particular, can a Recipient's MUA automatically formulate
| a valid Reply?
... that will reach the original Sender.
Behind a gateway ? Tricky. Auto-Replies go to the address in
the Return-Path. In my parallel universe it's the responsible
sender, i.e. some local part @ gateway.
In Dave's parallel universe it could be an address _set_ by the
original sender, it's not necessarily related to the original
sender. In fact most of the time it's an "innocent bystander",
the default case for mail is spam today.