Am I allowed to order a product from amazon.com where they have a guaranteed 2 day shipping policy on that item and it says it is guaranteed to be delivered on shabbos
The Halacha is that we are allowed to hire a gentile to do a job for us even if he actually does it on shabbos in his own property, if he wasn’t forced do to it specifically on shabbos. Therefore when ordering merchandise from a company on line, it depends if the company can realistically send it to you without doing it specifically on shabbos. From what I understand, that Amazon has numerous shipping warehouses, scattered throughout the United States, and they really can deliver it in one day, but the second day is more of a cushion, if that is the case then it is permitted.
This would apply to Amazon itself, however if he real seller and shipper is a small company located far from the shipping address, in a way that they would not be able to get it delivered on time unless they worked on shabbos then it would be problematic. However if the is a big need there are poskim we can rely on that it may still be done.
O:CH 247-1 M:B ibid 4, Chelkas Yaacov 1-65( 2) in the name of the Maharsham, that it is Amira D’amira, Machaze Eliyahu 1-37.