I suspect that something horribly broken is generating 8-bit crap; marks
it as 7-bit quoted printable; Courier sees that the MIME section
contains 8-bit data, and converts 8-bit crap to quoted-printable crap.
The final result is the same crap.
I can guess the answer to this, but did anything change from Courier
0.40.1 that would affect this? I'm told by the accounting folks that
these attachments have worked flawlessly "for years"...