You also doing the same!! You are right but do you know rediff will also not listen to you. It has happened loads of time here. And why rediff will take action if we ask them to do it, they also have mind / intellect / soul... but they are enjoying as visitors here are increasing in numbers... Very well going rediff.
I would suggest to rediff that you are authenticating the users through email, so if some number of abuses is reported for some one then his id should be blocked!! It will prevent upto some extant...isnt it?