Thirdlove is a digitally native, data-driven DTC brand pioneering inclusivity and fit in women’s lingerie. Known for its half-cup sizing, comfort-first designs, and modern approach to body positivity, Thirdlove has built a loyal following by combining proprietary fit data with elevated, everyday essentials.

As a performance-minded brand that has always championed personalization, Thirdlove wanted to see how AI-driven creative could take that philosophy even further.

Challenge

There wasn’t a problem to solve so much as an opportunity to explore.

Like most high-performing DTC brands, Thirdlove already segmented its audience intelligently based on engagement, purchase history, and lifecycle stage. But each promotional campaign still involved sending a single, uniform email template to large audience groups. The team wondered if certain customers might be predisposed to engage or convert on different layouts, tones, or visual structures.

In short, could the template itself be personalized?

Solution

Thirdlove partnered with Backstroke to put this theory to the test.

Across two campaigns, the team ran a 50-50 split test to 1.6 million subscribers using Klaviyo. Half received a control variant of the email, while the other half was divided into four predictive clusters, each receiving a unique variant chosen by Backstroke’s predictive modeling engine.

Backstroke analyzed purchase behavior, email engagement, and demographic attributes to forecast which template style each cluster would be most likely to click and convert on. The result: four dynamic creative variants, deployed seamlessly from Backstroke into Klaviyo in a single test (split across two campaigns).

Results

The predictive templates decisively outperformed the control version:

• Revenue per recipient increased by 25%

• Placed order rate rose by 16%

• Click rate improved by 23%

The findings validated Thirdlove’s hypothesis that different customers do respond to different creative formats, and demonstrated how predictive modeling can help marketers make those creative decisions across millions of subscriber profiles.

Customer Perspective

“Our team has always believed in using data to shape the customer experience. Backstroke took that a step further by helping us understand not just who to talk to, but how. By pairing predictive insights with creative execution, we saw clear performance gains and a smarter way to scale personalization.”
— Leanne Chan, Sr. Director, Retention and Performance Marketing, Thirdlove

Looking Ahead

Thirdlove now plans to extend predictive templates into additional campaign types and seasonal promotions, using Backstroke to continuously learn which creative strategies resonate best with each customer segment.

For a brand built on fit, this new layer of predictive creative personalization helps ensure every message fits just as well as every product.