Amazon has struck a deal with the U.S. Postal Service allowing customers in L.A. and New York City to get their e-shopping goods delivered on a Sunday–normally a tricky and expensive day for deliveries.

The service is will eventually be available in Dallas, New Orleans, and Phoenix as well as other cities. It is free for Amazon Prime customers, but for customers outside of Prime, the service does not cost anything extra on top of standard shipping rates.

This move is an unashamed ploy by Amazon to outmaneuver other digital shopping outlets in the run-up to the critical revenue-earning holiday season. Many buyers will no doubt to try to buy goods through Amazon instead of relying on weekday deliveries from other stores. Amazon is planning on keeping the system running all year after the holidays, which will help it earn revenues and possibly help with the future of the USPS itself.

Update: The Wall Street Journal is reporting that this new Sunday trick will also happen in the U.K. too. Londoners, and Londoners alone, will also be able to get Sunday deliveries later this month. And if the Sunday deliveries in the U.S. will upset some folks, in the U.K. it’s going to really hurt the Royal Mail because Amazon is going to use its own trucks.