Out of curiosity, then what is the value of "extras?" Was there
a time it provided value, before header content exploded?
Well, I don't mean to crap on anyone, Robert Elz in particular, but
you can kind of see what I would call the original MH thinking here:
https://lists.nongnu.org/archive/html/nmh-workers/2014-06/msg00084.html
But I think Robert comes from an era BEFORE everyone started cramming
non user-readable metadata into email headers. Whether or not that is a
good idea is not really relevant at this point ... that ship has sailed.
Honestly I'd be up for changing the default mhl file at this point, but
I am sure there will be objections :-)
--Ken