@K5GLH@mastodon.cloud As far as I know, there's no way to send truly private messages. If you start a fresh post (not a reply) you can put the address of the person you want to receive it in the message. Then set the visibility of the message to "only mentioned users", and that's the best you can do in terms of a private message.

This probably goes without saying but be aware that if you're talking about someone else and put their address in the message, they will see it.