What service allows merchants to return merchandise to the sender without additional postage?

The option that allows merchants to return merchandise to the sender without additional postage is Parcel Return Services. This service is specifically designed to facilitate the return of packages without the need for the recipient to pay additional shipping costs, making it a cost-effective option for both businesses and their customers.

Parcel Return Services streamlines the return process by providing merchants with the ability to include return shipping labels directly within their packages. This enhances customer satisfaction, as it simplifies the returns process and encourages customers to shop more confidently, knowing that they can return items easily if needed. This service is particularly beneficial for e-commerce businesses that often deal with higher return rates.

Other options, while they provide various mailing and shipping functions, don't specifically focus on managing returns without added postage in the same effective manner as Parcel Return Services.