Apologies; mh mail client breakage not your fault
If an email client should try to accept and display as much as possible
and try to muddle through as many problematic headers as possible, then
mh (the client I presently use) is certainly broken. I will therefore
file bugs against mh every time I can read a message with cat or any other
mail client or unix/linux tool, that I can't with mh.
Similarly, if an email client should try to send mail that is correct as
possible wrt headers and other infrastructure, then any client sending such
headers is also broken. So, I will file bugs against mh whenever I discover
that it is sending such erroneous infrastructure. It will certainly be
easier for me to discover when my client cannot read something, so I ask
to be informed when someone else cannot read mail I send.
Apologies to you, Kristoffer; it's not your fault that my client is broken.