> If I recall correctly, that is done as follows:
>
> Open a Gmail compose window
> -> click the "more" (3 vertical dots) icon in the bottom toolbar
> -> click on "plain text mode" until a tick-mark appears beside it.
>
> I believe that setting then applies to all future messages, until turned off.
Yes, thanks, it works for the desktop, but not for the phone.
If you see that these messages are written with
short lines is because I'm using a phone.