I'm honestly not sure (I don't have a Tumblr myself; I just read my wife's blog!) I think that probably users could block comments from people, or have some kin

I'm honestly not sure (I don't have a Tumblr myself; I just read my wife's blog!) I think that probably users could block comments from people, or have some kind of moderation over their own, but I'm not sure about flagging or any system globally.