How would you read messages sent only from certain people? I mean there's a whitelist but nothing like allowing a whole category of people.

Well if you're fine with ocular whitelisting then you could just try to not let the comments you find offensive affect you.

That sounds terrible. If someone is socializing or doing business, they don't want to wade through graphic death and rape threats at the same time. Even if it were possible to make themselves desensitized, why would they want to? That sounds like a recipe for not letting anything affect them, even messages they want.