I have just uploaded the mutt upgrade. To be found in

http://server505065.nazwa.pl

The tar archive contains mutt-2.1.4c, meaning all patches from 2.1.3 , 2.1.4
were applied, 'c' at the end means that almost all patches from 2.1.5 were also
applied. Only patch specific to NetBSD was not applied. New version works fine.
Good news is that I found why mailing of large messages fails badly. It is
enough to comment out folder-hook containg fcc-hook. As a result after sending the email mutt will ask what to do, You should enter 's' , meaning mutt should skip copying Your message to the folder on the server.Just to be clear, fcc-hook is defined in /.muttrc.

You will also find lynx.cfg, in which NNTPSERVER is set. Very useful.
You will also find two kernels, cohtestSAY44z and cohtestSAY45. Both kernels work in standalone system and in virtual machine.

BTW, You can easily send files from Windows 10 to Coherent virtual machine.
Simply mail the message to Yourself with the file attached and receive it in
Coherent machine using mutt :). Do not exagerate with the size of files, use
rather gzipped files :).

HTH