You might be interested in using kshowmail sometimes (i.e., kshowmail-trinity). Use kshowmail to preview only email headers; but you can also click to read plaintext versions of selected items. Bill
Sorry, me again.
kshowmail-trinity does'nt seem to exist, and also kshowmail (I'm on Stretch).
However, kshowmail exists for KDE.
Thanks,
André