Linda - your anonymous emailer does not hide her identity because she believes in what she says, but because she does not believe in what she says. She merely wishes to spread fear, uncertainty and doubt. For much of the world, this will work.
If she said who she was, then no one would listen to her. By pretending to be a specific person whom she is not she hopes to find the gullible who will believe. In a follow up letter where she claims to be a particular Mother, she reveals herself to be a fraud as that is not who she is.
The person is simply a troll - a person trying to spread Fear, Uncertainty, and Doubt.