--Boot Hill
At the moment there is a rash of "letter bombs" which bear a postmark "somewhere in Italy".
Someone who understands modern postal systems knows very well that it's pretty difficult for a fused charge of any kind to make it through the multiple stages of any facing/cancelling operation, or even through the various kinds of sortation equipment it will meet.
So, how do you get a letter bomb delivered if it's going to be triggered in transit?
First of all, you get it cancelled BEFORE you put the bomb into it. I can think of several ways to do that.
Then you load the envelope with the explosive device and hand carry it to the delivery location.
The FBI, among other police organizations, would go crazy investigating the post office of origin where the bomb was loaded into an already cancelled envelope.
It's really not all that difficult to find folks willing to cancel an envelope or two ~ in fact, the USPS will do it for you for a modest fee (as an ordinary feature in the philatelic servicing business). You can find out what post offices are busy with some sort of commemorative cancellation right in the Postal Bulletin (or it's foreign postal system equivalent.)
BTW, I've seen envelopes disintegrate in an 010 operation, stuff flying everywhere. Was it a bomb? Was it bad paper? Was it just that envelope's turn to self-destruct? Best advice when you see that happen is to reverse course, go somewhere else, and call the Inspectors because, after all, it could have been a bomb and where there's one there's two, or maybe three, or more!
My suspicion is there's someone inside AlQaeda who understands the equipment and workings of modern postal systems. They are not smarter than the USPS folks, or even the foreign postal administration people, but, since the advent of the student loan system, they have become much smarter than the FBI in this regard.
Both the present letter bomb problem and the Anthrax Attack of 2001 could be solved in a matter of days by putting postal system experts to work and pulling back the accountants and lawyers at the FBI.