KMail 17.08.3 mail composer always initially in rich text mode

[Martin Steigerwald <martin@lichtvoll.de>]

Hello.

Since some time of using KMail 17.08.3 (not with 17.08.0) I have it that the 
KMail mail composing editor always starts in rich text mode.

I certainly did not tell it to do so. I checked the global settings and its 
disabled there.

I also searched through settings inside the identity or the folder but I did 
not find any setting regarding the mail editor there. Also it happens 
regardless which folder is selected when sending a new mail. Also it happens 
when I reply to plain text mail.

Does anyone have this issue? Is there any setting I missed?

Thanks,
-- 
Martin