My users put that authority in my hands, they dont want to deal with it and they dont have the time.
I use the blacklists because it makes them happy, and they dont care if that single email is blocked, because only an idiot would rely 100% on email for something major.
Well basicly most my users have the same with the default settings. But if they need to make sure a "friend" bypass any filters they have the power to do that. And to also raise there default score reject level. Or ban addresses. See what incoming email messages were rejected, etc. etc.
Now this is done with newer mail server software (I use
Surgemail). That doesn't require a full time mail admin changing settings, managing black/white lists for his end users.