By offering complimentary shipping with sign-up, retailers are capturing valuable customer data like email addresses.

In an age where retailers’ email lists are valuable marketing tools for targeting customers, some merchants are coming at it in an innovative way. A number of retailers are luring shoppers into creating accounts and handing over personal data by offering free shipping with no minimum purchase when they sign up for a free loyalty or rewards program.

Here’s a look at how much customers can save on shipping per order—a cost absorbed by retailers—when they provide their email account, name and often address, birthday and gender.

While shipping for most of these retailers—the majority of which sell apparel—is in the $5 to $10 range, loyalty membership can save Musician’s Friend customers about $70 in some cases. The musical instrument merchant offers free UPS ground shipping on many items even for non-members, but instruments and accessories that weigh 50 pounds or more are charged a freight fee of $69.99. But this shipping charge is waived for Backstage Pass holders.

Of the retailers ranked in the Internet Retailer 2018 Top 1000, 614 of them market some sort of loyalty program. While seven merchants offer free shipping when a shopper signs up for a free loyalty membership, 28 additional retailers have free shipping associated with various paid membership or higher tiers achieved as reward points are accrued.