There does not seem to be a possibility in the app to switch off autocorrection etc.
E.g. each time I write an email in German, the app sets my first word after the salutary line (i.e. ‘Sehr geehrte Herren,’ which corresponds to ‘Dear sirs.’) with a capital as its first letter.
This, however, is not correct in German. Why can any attempts by the app to edit what I
write not be switched off?
I just tested that and it’s not a setting in K-9 but your keyboard.
I disabled “Automatically capitalize after punctuation” in Swiftkey and then K-9 no longer started the next word after “… Damen und Herren,” with a capital letter. But then you have to manually capitalize at the beginning of each sentence as well, so for ME that’s not worth it and I enabled that setting again.