Helfman, 54, is used to getting a lot of email at his company, a contractor recommendation site based in Bloomfield Hills, a suburb of Detroit. He typically receives about 200 emails a day, but about two weeks before Thanksgiving, that number exploded to more than 700 messages daily, mostly marketing spam.

“It’s created an animosity between me and some companies where I just will not buy from them at all anymore,” he said. “There’s another company where I liked the brand but there were so many emails all day long, and they show up in your social media feeds and in online ads and it’s everywhere.”

A writer for The Washington Post reached out to True Classics and received promotional emails less than five minutes after simply visiting the site to obtain the media contact. The company initially offered to respond, but ultimately declined to comment to The Post.

Because it’s so cheap to send automatic emails, companies are willing to risk alienating customers for as little as a 1 percent increase in total purchases, Hanna said. Even if the customer unsubscribes from a marketing list, they are back on it immediately if they visit the retailer’s website or order again.

To a certain extent, retailers’ interest in reaching the consumer has always been intense, said Robert Passikoff, president of Brand Keys, a consultant specializing in consumer loyalty. But the pandemic exacerbated the push for app and email notifications as more people moved to online shopping, Passikoff said, adding that technology also made it easier than ever to reach customers.

Brand Keys this year surveyed 2,208 consumers ages 16 to 55, and asked them to rank the companies who contacted them the most. A similar survey was completed in 2018. Amazon ranked No. 1 both times. Macy’s was in second place this year, up from ninth in 2018. Groupon was No. 3 this time, dropping one spot.

Although Amazon sent the most emails, customers said they engaged with them more because they were personalized and often offered good news, Brand Keys found. For example, they might send an email refunding the customer 71 cents because the price of an item they bought went down, Passikoff said.

Under U.S. federal law, companies that send marketing emails must give consumers the option to opt-out of receiving them, and they must honor that request within 10 business days. Respondents to this year’s Brand Keys survey said many companies have made it easier to unsubscribe these days, with the link clearly at the top of the email. In previous years, people complained that the link to leave was often at the very bottom in tiny letters and in colors that made it hard to see, but Google’s popular Gmail service often automatically puts “Unsubscribe” links at the top of marketing emails these days.

Passikoff ordered a wallet last year as a Christmas gift for his wife, and the result made him “terrifically happy.” The next day he got a survey, under the company president’s signature, asking how he found out about the business — a common technique for customer mining, Passikoff said.

“I want to know that you got my order and you sent my order,” she said of Kohl’s, which did not return messages seeking comment for this story. “I don’t need seven emails telling me a dude walked across the street to get the materials for the dress, and now you’ve got the box, and you’re putting it in the box.”