you need the external html2text script for this to work. Originally written by Aaron Swartz, forked often and now available via PyPi or in your repos. NOT this one !!!1elf
in Arch, the package is in
community repo and is called python-html2text.
set '(mu4e-html2text-command "html2text --ignore-images --protect-links \\ --unicode-snob --no-automatic-links \\ --no-wrap-links --reference-links --mark-code")