[Battle Axe]

When I look at the whole picture I see something.

The planes were to go special places.

The envelopes were to go to OTHER special places.

Not a plane AND and envelope. And I agree with one poster who thinks Atta was involved, and that they could have been mailed prior to Atta's leaving Florida.

My logic tells me that they expected the envelopes to reach their destinations.

[winodog]

Grand Central Station must have some areas where the wind or fan or HVAC system creates a good breeze. What would happen if this envelope were sprinkled in front of this breeze?