Conversation so far:
What was the Judith Miller anthrax hoax about?
On October 12, 2001, Miller opened an anthrax hoax letter mailed to her New York Times office. The act was a copycat hoax of the 2001 anthrax attacks.
Who was the anthrax hoax letter to Judith Miller mailed from?
The most likely suspect was Bruce Ivins.
Why was the anthrax hoax letter mailed to Judith Miller ?
The exact reasons is unknown, but the letters were sent for political or revenge related reasons.

Question: What was the content of those letters?
Self-contained rewrite: What was the content of the anthrax hoax letter mailed to Judith Miller?