Keith Moore writes:
MFT can cause the replies to go to some other set of recipients
without the responder realizing this.
My MUA shows me the original message along with the reply under
construction. To-line differences are already reasonably clear, although
I suppose automatic highlighting of the differences in red would save a
moment of reading.
But the point you keep missing is that the original sender and the
original recipient are _cooperating_ to send followups to the right
place. Sure, there are occasional disagreements, but _usually_ the
recipient wants exactly what the sender specified in Mail-Followup-To.
My MUA does this by _default_ to save editing time for the user.
USENET has always allowed the original sender to specify Followup-To.
The recipient can select a different followup target but _usually_ wants
exactly what the sender wants. That's why the recipient's software uses
Followup-To as the _default_ followup address.
Should the recipient know what's going on? Of course. Should the
recipient be able to edit the target list? Of course. But this is not an
argument against Mail-Followup-To.
---D. J. Bernstein, Associate Professor, Department of Mathematics,
Statistics, and Computer Science, University of Illinois at Chicago