Well, the special part about anonymous Tells is that we don't reveal who sent them. This is not going to change in the future.
However, in cases of content that is strongly violating local laws, we do work with law enforcement agencies to find the person that is responsible.
If you consider messages you received as threatening or strongly offending, you can always make a report to the police. After that, the police will get in touch with us and we may be able to provide them with information about the sender.
So, to conclude, you are not going to find out who sent you a Tell. At the same time, you are still always protected by local laws and our terms of use.