Since it is coming up again:

Mastodon isn't private.

Expect anything you toot to be visible to everyone, regardless of your settings for visibility.

Mastodon is built on a system that isn't appropriate for private conversation and the work arounds for private toots and the like are not in any way robust against someone just ignoring them.

@inmysocks That's not exclusive to mastodon, this can happen with any social network. If you want private and encrypted communication there are a lot of alternatives (e.g. Signal).

@JORGETECH yes, that is kinda the point of what I said.

Although the dependence on phones makes me dislike signal.

@inmysocks Signal was just an example I gave, I bet there are many others that are not phone dependent.
@JORGETECH yes, I mentioned two of them in my original toot.