The USPS appears to be misrepresenting its ability to deliver large and/or heavy packages. It does so in writing on its various websites where the weights and sizes of packages it accepts are published. The fact that others have experienced this suggests that it is not a one-off issue but that there is likely an element of knowledge and intentionality on the part of the USPS administration. What then is missing from the definition of fraud ?

As for

> Is there a guarantee in writing that they will deliver it to your door?

I'm not sure, but I believe that is the general understanding most people have of the nature of the service being offered. If the USPS and/or Amazon were clear that by deliver they mean send a package to somewhere within a few miles of where you live then consumers would be able to take that into account when deciding which vendors to frequent (and many who are able would probably opt for their local Home Depot over Amazon). Moreover it would open the marketplace for competitors to offer higher quality delivery services on fair and clear terms.