The U.S. Postal Service said Monday it is offering free bags to people who send items to it in the mail, a move it said will encourage people to use their credit cards.

The Postal Service is offering bags for free to people in its mail-delivery network and its global network of hubs, which carry about 50 million packages.

The service has not yet posted any details on the bags, which can be redeemed for a number of items including postage, and will begin in January.

The service also plans to offer discounted merchandise and merchandise that has been donated to a local nonprofit organization.