Okay, so it caused a lot of damage and blew out a wall.
And, if we assume it was a package bomb, we can assume that it was not addressed to Barbara Bush the Younger. Barbara's stuff is vetted by Secret Service. Besides, it had to be addressed to the Yale Law School. Barbara is an undergrad.
If the bomb came by mail, it was most definitely meant for someone at the Law School.
BTW, just a thought. I'd get some Hazmat people out there ASAP to check for chem or biotoxins. That would make very good sense from the terrorist standpoint.
Be Seeing You,
Chris