What about for something like a !points command? A point bot would be the perfect candidate to send whispers to individual users: It’s something that really only effects the user (Other people don’t care how many points you have…they care what they have), and would reduce a lot of spam if those messages were sent in whispers instead.
There seems to be a whitelisting system at Twitch: But from what I’ve read, it’s based on previous whispers. How exactly does one get a bot whitelisted, if it can’t send any whispers to begin with? This is a pretty big blocker for our project.
My suggestion is a phone verification system: It seems to be the best way to ensure that an actual person owns an account. With phone verification, it would be the first step for allowing a set number of whispers per hour, and as long as messages aren’t being reported as spam, then the system should continue allowing whispers.