> 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,

Andr�