Another friendly reminder:
Mastodon is awesome, but mastodon isn't an appropriate tool if you want private communications. DMs aren't actually private, they can be seen by instance admins and maybe by other people, it isn't at all secure.
Mastodon and GNU social aren't made for private conversations, if you want to have a private conversation there are many tools that are appropriate for that.
I suggest Tox, but Cryptocat and XMPP with OTR are also good. There are others but I have used those
Telegram (the app, not the 19th century version of SMS), is also quite good for easy, encrypted chats.
@ChristianD telegram is supposed to be mostly good, the only complaint I have is that it uses a server you don't control, unlike Tox. But that is the only downside to it and that doesn't matter in most cases so I am just being unreasonably picky.
@inmysocks
I actually really like that they use server so that you can sync between all your devices. It does cause some privacy/security terms, though :/