No. Never agree to payment after delivery. This a UPS coined idea that allows a seller to setup a package as COD (Cash on Delivery). CODs are bad. A buyer may refuse and if not properly arranged can actually cost you more than you'd like.
No its not!! Pay after delivery is set though Paypal, not UPS. Paypal pays the seller, and you have 14 days to pay Paypal back for the purchase.
You mean Paypal's Bill-me-later. OK, yes that's an option. The OP made it seem like a COD type of arrangement. Don't you just love clear questions.
Pay after delivery and bill me later are two different services. Pay after delivery is PayPal paying the seller then charging your account two weeks later. No credit checks. No further payments. Bill me later gives you a credit line built into your PayPal account that charges no interest if paid for before a certain amount of time.
C.O.D. (Collect On Delivery) is not usually a good idea for sellers or buyers. There is usually a hefty charge by USPS for this service. By the way, the "C" doesn't stand for CASH but rather COLLECT which isn't the same thing.