In 110 A.D., Pliny the Younger, Roman governor of what is now northern Turkey, wrote a letter to the Emperor Trajan about how to handle Christians.
Pliny specifically mentioned a booklet - anonymously submitted to him - with names of supposedly secret Christians. He asked Trajan what to do, since he had never dealt with the problem before.
Trajan famously replied that Christians are not to be hunted down. And as for anonymous sources, "they are to be ignored, for they are not worthy of the tenor or our times."
How far have we fallen!