My 16 year old DD has a blog on Tumblr which she really enjoys using. Long story short, she has been getting anonymous messages some of which have been quite offensive (eg calling her a slut and a c*) which she thinks are from the best friend of her BF's ex GF. She is more angry about it than upset and we know she could block "Anonymous"--but she would then lose communication with other anonymous people who sometimes send her lovely messages. She thinks that the same person has been tweeting about her, eg "Bitches get stitches" which sounds pretty nasty to me. But no hard evidence about who it is. I've done a bit of research about what you can do about this kind of thing but it's all about how to block them (as above, if she did this she would lose other anonymous communication which she values). Anyone had experience of dealing with this kind of thing or got any advice? Is it worth reporting to the police even?