They knew how long a letter had to be in the postal system before the anthrax spores would filter through the envelope paper. They knew how much of the paper to wrap with plastic packaging tape to limit the amount of filtering paper exposed to the outside world.
Their idea was to design an envelope such that in 3 or 4 days time all or most of the anthrax spores inside would filter to the outside and be distributed with the maximum effect on airport operations. After all, by being mailed in Florida the terrorists guaranteed the letters would FLY. The envelopes would have been inside Washington National or Dulles International, and/or John F Kennedy airports at the time they began leaking copious quantities of anthrax powder. Thousands of passengers would have been exposed and the powder would have been carried all over the world as well as the United States.
(NOTE: The terrorists made a mistake in this judgment since the three targeted airports have separate mail terminal handling facilities and the letters would never have gotten into the same ventilation system as that serving the passenger terminals, but in most of the world it is commonly the case that mail goes right through the baggage and express operations. In the US mail volumes are far, far higher so they are segregated.)
In addition, the letters would have passed through the main postal facilities in New York City and Washington DC thereby, the terrorists hoped, bringing down those facilities, their normal mail flow, and consequently the economy and government of the United States.
They knew normal mail routings, they knew paper characteristics, and they understood weaponized anthrax spore flow rates. They also had a very devastating plan which would have caused hundreds of thousands of deaths and worldwide panic!
They didn't, however, count on the USPS providing poor service to single-piece rate hand addressed First-Class letter mail entered in city mail collection boxes on Friday evenings after the last prayers.
And that, BTW, proves, positively, that no one in USPS management or top level technical or administrative jobs were in on the attack. If they had been, they'd made sure the letters were entered in a 3-digit working tray of FCM letters brought to the post office by a major mailer.
That also demonstrates that no one working for a private sector letter shop helped organize the plan.
This leads me to conclude that the plan was drawn up in a foreign country where they have a substantial mail service, e.g. France, UK, Germany, Russia, Italy, Australia ~
Instead of looking for the guys who made the anthrax, the FBI would have been better served looking for the postal operations analyst who drew up the plan. There couldn't be more than 100 people in the countries I've named who would know how to do it.
Gene, you still following this thread?
Thank you muawiyah. I hope you don't mind if I come back with more pestering questions