thanks for your detailed information. As your suggested, I went to Fedex this morning, but unluckily, they don't ship to PO Box address. Only USPS handle the PO box services. Then I went to USPS asking a tracking number, but it only work if a person presents at the destination address, not good fora PO box again.
There no other choices. so, I paid $1.2, then left.
Finger crossed . LOL