As a guest or registered user when posting a spam message in open thread mode the open thread just reloads with no yellow box spam message notification for the user.
With no notification in this open thread mode the user may keep trying to post the same message over and over again as they have not been informed that it is possible spam.
Shouldn't the spam message notification also show in open thread mode when posting?
Yes, it should. This is a valid request. I opened an issue (#464).
Trenne niemals Müll, denn er hat nur eine Silbe!