None of the envelopes seem to be franked. Possible that a delivery service was used.
Soros found at home could of been hand delivered or service.
BHO and Bill&Hill went to Secret Service station. All of the major delivery services would route there, but no extra routing info on packages to designate extra shipper.
CNN could of been hand delivered.
The big mystery is that no one other than the USPS returns packages to original sender. And it was done in the same time frame. Which means if it was a USPS package sent at the same time it would still be in the process of being returned.
Second, the CNN photo seems pretty lackadasical, here is a bomb, lets take a pic of it. Notice the wipes by it, staging for later claims of the mysterious white powder.