AmazonFresh, the grocery delivery service run by the retail giant in selected US west coast cities, has started a trial program which sees the US Postal Service shipping its items. The 60-day program, which started in August, tasks the USPS with delivering food items, toiletries, and other everyday essentials to customers in the San Francisco area. Items are scheduled to be delivered between 3 AM and 7 AM, when most of the USPS trucks arent in use anyway.