From page 43 of the Expert Behavioral Analysis Panel report:
"Among the recipients of the first set of anthrax letters was the parent company of the National Enquirer, American Media Inc. (AMI), then based in Boca Raton, Fla. The address of the parent company at that time the address to which the letter was sent was the former address of the National Enquirer itself, as listed in the back issues that had piled up in Dr. Ivins' office. One copy of the paper was found in the hot suite."
There was no anthrax letter at AMI. No such letter can be shown.
None. All that you can do is whine about someone's thoughts about such a letter being mailed.
...but no anthrax letter was ever found there.