Yesterday doesn't exist, either, but we know it did exist because there is evidence that it existed. And there are over 6 billion witnesses.
The argument that the letter never existed is even more crazy than the argument that the anthrax was on rent money where no one saw the powder, no one knows how the rent money got into the AMI building, and no one can explain how a powder that no one could see on the money could kill one person, infect another, contaminate an entire building, and leave a trail of anthrax through post offices from Trenton to Boca Raton.
Except for you, is there is anyone on this planet who believes your preposterous theory?
There was never an anthrax letter at AMI.
There is no AMI anthrax letter in any evidence bin today.
You view the above as inconsequential. You are wrong.