On Thursday, 25 June 2020 15:55:41 BST Matt Connell (Gmail) wrote:
> In KDE KMail, when I enable the "only quote selected text when replying"
> feature under Configure -> Composer -> General, the reply behavior
> doesn't seem to change.  That is to say, if I try to select a line of
> text, and reply (as one would do with a mailing list, for example), the
> reply window quotes the entire message instead.  I've tried unchecking
> and rechecking the box, with an 'apply' after each change, to no avail.
> 
> Is this a bug?  How can I troubleshoot/fix this?
> 
> Kmail Version 5.13.3 (19.12.3) (according to the about panel) using the
> following profile: default/linux/amd64/17.1/desktop/plasma

I'm replying to this message using the same method of selecting only part of 
your message and evidently it works - I have left out the first paragraph of 
the original in my selection.

I have the same kmail version and profile like you.

Regarding the settings under General/Format, all are enabled except for 'Reply 
or forward using HTML if present'.  The word wrap is set at 78, not sure if 
this is the default and/or if it makes any difference.

Given the above it ought to work - or at least it does here.  Perhaps if you 
move out of the way any ~/.kmail2rc and restart kmail, it will create a 
default file for you to compare its contents against.