When you buy something on Amazon, the e-commerce giant isn’t always the one making the sale; an estimated half of all products sold on Amazon come from third-party sellers. Amazon says it’s merely the conduit between buyer and seller, and doesn’t bear responsibility if a third-party product is defective (although some recent court cases have challenged that stance).

Third-party sellers aren’t supposed to be able to email Amazon customers directly outside of the platform, but a new report in The Wall Street Journal shows that some sellers can find ways to get in touch with buyers who leave negative product reviews, and some businesses even offer “email extraction” for buyers as a service to sellers.

So rather than paying people to give favorable reviews, a practice Amazon banned in 2016, these third-party sellers go after people who leave a bad product review and offer them payment to change or delete it (a practice which is also a violation of Amazon’s rules). Nicole Nguyen writes in the WSJ about Katherine Scott, who bought an oil spray bottle for cooking which didn’t work as advertised, so she left a negative review. A week later, she got an email that looked to be from a customer service rep from the oil sprayer company offering a refund if she deleted the review.

Ms. Scott asked for a refund but didn’t want to delete her review. Another representative reached out the next day and declined to issue her refund. “A bad review is a fatal blow to us,” read the email. “Could you help me delete the review? If you can, I want to refund $20 to you to express my gratitude.” (This was twice what Ms. Scott paid.) A few hours later, she received another plea from the same email address.

Amazon told the WSJ it does not share customer email addresses with third-party sellers, and that it removed some 200 million fake reviews last year alone. But Nguyen writes that third-party sellers are finding ways to email customers all the same. Go read this excellent report which includes advice for how to shield your email address from Amazon sellers who shouldn’t have it in the first place.