Like, message people stuff that only they can see, like on Discord?
Can you DM people here?
person_off
Deleted user
As long as the user has an @ user name, you can do that, yes. In the top right of your screen beside "settings" it should say "inbox". Click that and there will be an option that says "start a new conversation". You then type in the title of your conversation and who you want to be in it and voila. Hope this helps :)