As alternative ownership models become increasingly popular in fashion, culminating in reports last week that The RealReal could be closing in on a $1 billion valuation, an interesting strategy has developed from frontrunners in this area including The RealReal and Rent the Runway: personalized emails breaking down the individual customer’s impact (on the earth, on their pocketbook) from using these platforms.

Customers who use these platforms get yearly emails breaking down how much money they saved by buying something pre-owned or renting it, as well as how much their actions are impacting the environment. The latter is one of the biggest motivators behind The RealReal’s email reports, which break down the amount of water and driving miles saved by buying pre-owned rather than new. They also include greenhouse gas emissions and overall energy saved. Both The RealReal and Rent the Runway’s email reports are compiled in-house by their data-science teams.

For The RealReal, the main appeal of this strategy is to educate consumers and to make the tangible impact of their choices more obvious.

“Our clients have told us for years that the sustainability element is one of the biggest motivators for buying or consigning with us, but for the first time, we really wanted to be able to quantify exactly how positive consigning is for the environment,” said Allison Sommer, director of strategic initiatives at The RealReal. “This is our first and biggest effort to translate what the circular economy means in a tangible way to consignors.”

Rent the Runway does something similar with its personalized reports, which break things down by carbon imprint and water waste, equating them to more understandable, everyday measurements — for example, 6,000 bubble baths’ worth of water saved.

Rent the Runway also goes further, giving customers deep personalized dives into what their most-rented categories were, the designer brands they rented most and how much everything they rented would have cost if they bought it all new.

Neither company would offer specific details on how much these emails drive customer retention or increase sales, but both are confident in their audience’s interest in seeing their sustainability impact and will continue these reports going forward.

“I think a lot of our target audience is realizing that most of their closet is only getting worn a few times and really they want to be more sustainable,” said Maureen Sullivan, COO of Rent the Runway. “Fashion is huge and yet a massive portion of all of it goes into the landfill. People are becoming more aware of what they can do on an individual level.”

Email as a whole is one of the more underrated areas where brands can deepen connections with consumers and solidify loyalty and retention. The level of personalization that brands can engage in through email is a major selling point, allowing for cost-effective but highly granular interactions with consumers. Brands can offer more personalization than just acknowledging a recent purchase and can dive deep into the customer’s habits and likely future purchases.

“Email is still going strong,” said Kris Mobayeni, avp of marketing at BounceX, a company that was instrumental in revamping the email strategy of Clarks. “It’s so much more accessible and so easy to reach people with fairly simple but effective stuff.”