Companies may be able to significantly increase repeat customer participation in recycling and reuse programs with a surprisingly simple strategy: sending an acknowledgment message. A new study led by researchers at Penn State found that a basic email confirming receipt of returned items, such as reusable food containers, coffee pods or used electronics, encouraged customers to participate again. The findings, published in the Journal of Consumer Research, suggest that this low-cost approach not only strengthens customer engagement but also enhances a company’s reputation for sustainability.

The research began with an everyday observation about single-use coffee pods and whether companies could motivate customers to recycle more consistently. Across a series of seven experiments, the researchers discovered that simply acknowledging a customer’s participation was more effective than expressions of gratitude alone. According to co-author Sara Dommer, assistant professor of marketing at Penn State’s Smeal College of Business, customers who received a message confirming that their returned item had been received were more likely to participate in the program again, helping make environmentally responsible behaviour more sustainable over time.

To understand why acknowledgment works, the researchers conducted multiple online experiments involving more than 3,700 participants. In the initial studies, participants imagined taking part in a fictional coffee pod recycling program and received different follow-up emails. Those who received acknowledgment messages consistently reported stronger intentions to participate again than those who received no acknowledgment or only general thank-you messages. Additional experiments showed that acknowledgment strengthened consumers’ emotional attachment to the company, increased their sense of partnership with the brand and led them to perceive the company as more committed to sustainability.

The researchers also found that acknowledgment was especially effective among customers who were less connected to a brand. Rather than reinforcing the behaviour of loyal customers who already participated regularly, acknowledgment messages helped engage infrequent participants—the very group companies often struggle to retain. Another experiment demonstrated that the positive effect was unique to sustainability initiatives. Acknowledging participation in a take-back program increased future engagement, whereas acknowledging unrelated actions, such as submitting an online review, did not produce the same response. The study also showed that perceptions of greenwashing reduced customers’ willingness to participate again, highlighting the importance of authentic sustainability efforts.

The team’s findings were reinforced through a real-world field study conducted with Topanga. This foodservice technology company partners with Penn State to reduce single-use waste in campus dining halls. Students ordering takeout meals in reusable containers received an email each time they returned a container, confirming receipt and showing how many disposable containers had been diverted from landfill through their participation. Over the one-month study, the researchers tracked 710 participants and sent 1,589 acknowledgment emails. Compared with baseline data from the previous year, repeat participation among infrequent users increased threefold after acknowledgment messages were introduced.

According to co-author Karen Winterich, distinguished professor of marketing at Penn State’s Smeal College of Business, take-back and reuse programs depend on ongoing participation rather than one-time actions. The study demonstrates that a simple acknowledgment message can help companies build stronger relationships with customers while encouraging long-term sustainable behaviour. Following the success of the Penn State project, Topanga expanded the acknowledgment messaging system to partner institutions across the United States, demonstrating how a small communication can have a meaningful impact on customer engagement and environmental sustainability.

More information: Yuly Hong et al, Received! How Acknowledgment Increases a Company’s Sustainability Image and Drives Repeat Customer Participation in Take-Back Programs, Journal of Consumer Research. DOI: 10.1093/jcr/ucag007

Journal information: Journal of Consumer Research Provided by Penn State