John Ascroft can say what he wants, the real issue is what will the U.S. Postal workers do? I don't think that they will just keep collecting mail and sorting it if they think their life could be endangered. Same is true for UPS, FedEx, etc.
At that point the mail will be quarentined and very carefully examined to determine which has "powder" and what things, fingerprints, etc are in common with the contaimnated mail. Post Office video cameras will be reviewed and perps will be arrested.
The point is that the delivery system for a biological attack will not keep on operating and serving as a delivery mechanism for the biological agents. The terrorist threat delivery system will shut down and stop being a terrorist delivery system very quickly.
It appears your argument with my theory is not the theory itself...it is with the idea that a terrorist could have that the mail could keep going. You are arguing as if I believe both sides of this (fed and terrorist) were in on the plan...only one side is. If the terrorist believe that we won't shut down the mail, they could lose when we do. If we don't, they could win. I am not writing a book Robert, there is no plot, any side can change focus and direction here or make a mistake in judging its opponents reaction.