uShip offers a great alternative to DHL and UPS for box shipping. When you list your boxes in uShip’s online shipping marketplace, thousands of customer-rated transporters compete to win your business. They are able to offer discount box shipping because they are filling extra cargo space and passing the savings on to you. uShip also doesn't have prohibitive parcel weight restrictions.
As you are listing your boxes for transport, be sure to have the dimensions and weight handy, as well as origin and destination addresses and the time frame you have in mind. This will make the listing process much smoother. Once your boxes are listed in the uShip marketplace, you will start receiving bids from independent owner-operators as well as brokers. The former offers personalized service while the latter can get you major discounts on box shipping via DHL and UPS because they themselves get volume discounts. Either way, you win!