Who doesn’t love getting packages in the mail? And who doesn’t love free stuff?

A new Amazon pilot program, detailed in Axios, aims to give some users more of both, by allowing certain brands to send free samples to Amazon users, based on their purchasing habits. The idea being, if you get something free and really like it, you’re likely to buy more.

And Amazon is betting that it knows exactly what you’ll like.

A November 2018 listing on the Amazon employment site for “BizTechLeader, Sampling” provides some clues about how the program works. Amazon and its advertising partners, using users purchasing data, would create a sample-driven advertising strategy with the goal of driving “product awareness and conversion” of that product.

Some customers are already getting freebies: Axios reported that there have been examples on social media of people receiving free products from major brands like Maybelline and Folgers. “Amazon sent me a random coffee sample,” said one Twitter user. “Is it because I have like 15 (different) types of coffee in my cart.”

Some customers are already getting freebies from major brands like Maybelline and Folgers.

If it all sounds too good to be true, it very well could be—for Amazon, its advertisers, and its customers.

Like a free-sample at the food court in the mall or a grocery store, many consumers will simply enjoy the freebie and walk away.

Others may feel encroached upon when receiving a physical item in their home, as opposed to a digital ad on their phone or laptop—especially given the recent disclosures about intrusive data practices of big tech companies.

Whether customers will indeed be delighted—and if that delight converts to future purchases—remains to be seen.

In the meantime, keep your eye out for a surprise delivery.