After having used Hubzilla for about 3 years, I feel rather embarrassed to ask this question, but I can't find the real answers anywhere.
How do I send private messages? I read about using @!<username>, but if I use that in a thread, the literal text will be rendered, for everyone to see. If I reply to a private mention, everybody can still see the reply, also if I change the @<username> to @!<username>. And in the reply-screen, I have no privacy-setting where I can select the user(s) that should get that message.