Looks like it does work for qmail-inject, but there's some problem
with /var/qmail/bin/sendmail that prevents it working from there
(though Mate has had slightly different results from me pertaining
the defaulthost file -- for him, it gets into the Return-Path, but
it doesn't seem to for me using Emacs).
Now the difference is that defaulthost is working on my home machine
which has 20.1 installed---and qmail 1.01.
But defaulthost is not working on my office machine (20.3 and
qmail-1.03).
But now I want to double check my home machine---later today.
Mate