Web-only luxury consignment retailer Tradesy Inc. is benefiting big time from deep links.

Deep linking is when a consumer taps on a link on her smartphone that can detect whether or not she has downloaded a brand’s app. If she has downloaded the app, she lands on that page in the app. If she hasn’t download the app, the link will launch the page on the brand’s mobile site.

Email and mobile are both key to Tradesy’s business as 35% of the merchant’s gross merchandise volume is generated from email and 60% is generated from mobile devices, says Sash Catanzarite, chief product officer and co-founder of Tradesy.

The web merchant, which began adding deep links in its marketing emails at the end of January, found that the average order value of a shopper making a purchase after tapping on a deep link in the app is 12% higher than if the consumer tapped on the email link on her smartphone and was redirected to the Tradesy website, Catanzarite says.

What’s more, the average order value of a consumer that came to the Tradesy app from a deep link is 24% higher than a consumer who launched the app directly from her smartphones, Catanzarite says.

Catanzarite says 60% of Tradesy shoppers use more than one channel to shop. Tradesy is confident that its mobile site provides a great customer experience, but Catanzarite knows that at times it is best to direct shoppers to its app, he says.

“If you open the email, click on a link and the mobile website launches, and your whole experience so far has been through the Tradesy app, that’s not the best experience,” he says.

The same is true for consumers who have not downloaded the app. Tradesy wants those shoppers to go to its mobile site, and not have the link direct her to the app store. “Many people on the email list are just casual browsers and are not ready to commit to downloading an app,” he says.

Tradesy A/B tested the deep links from mid-December to mid-January. During that test, the conversion rate of consumers who received a deep linked email was 27% higher than consumers who did not receive a deep linked email and the merchant’s gross merchandise volume increased 24% from the deep linked group, Catanzarite says.

Tradesy launched its iPhone app in 2012, soft launched an Android app in March 2016 and fully rolled out its Android app in January 2017. Catanzarite declined to share download numbers.

On average, the app’s conversion rate is four times higher than the mobile web, Catanzarite says. The app has the highest conversion rate among the mobile web and desktop channels, although desktop has the highest average order value, he says.  On average across all channels, Tradesy’s average order value is $354, Catanzarite says.

“If you are going to buy a $10,000 handbag, even if you discovered it on mobile, you are still going to do that purchase on desktop,” he says.

Tradesy used mobile marketing vendor Branch for the deep links. The merchant rolled out the project over three months and had an engineer, its email marketing manager and Catanzarite working on the project. It didn’t take much engineering and most of the work for Tradesy was during the A/B test because the email marketing team had to develop two different emails, Catanzarite says.

Branch charges merchants on a volume basis for the deep linked emails ranging from a few hundred dollars to $30,000, according to Branch. Tradesy pays Branch a monthly fee for the deep links, says Catanzarite, who declined to share specifics.

“Our goal is to make sure we are ROI positive on the revenues we are generating—not just gross merchandise value—compared with to the cost we are paying,” Catanzarite says. “We have significantly exceeded that target during the test.”