As a consumer today, getting more emails than you can keep up with is more often than not the status quo. In fact, one of your daily rituals likely includes checking the ‘select all’ box and deleting promotional emails in bulk, without even really looking at the contents of each. For retailers trying to muscle their way into your inbox among a sea of competitors, knowing the right cadence of how many – or how few – emails to send can be daunting. Because of this, many err on the side of the ‘more is better’ mentality, but that couldn’t’ be further from the truth. What’s more – it could actually be harming your brand.

According to our new study on email marketing effectiveness, while email continues to be a vital part of a retailer’s marketing strategy, many are simply slamming their customers. Despite the sweet spot being an average of one email per day, the study found that, of the top retailers evaluated, on a day they send an email, over a third of the time they are sending more than one a day. Pottery Barn, The Shopping Channel and Victoria’s Secret sent two emails a day more than 90 percent of the time. If you think that’s a lot, Williams-Sonoma had the highest average email sends per day at 3.14!

While retailers run the risk of annoying subscribers by sending multiple emails daily, the real danger isn’t people actively unsubscribing from emails, as our CEO James Glover recently shared in an interview with Business Insider. Instead, it’s emails that can’t be delivered. If a retailer sends marketing emails to a customer for a year, and the customer doesn’t open a single one of them, the address is then registered by the email provider as “undeliverable.” That means emails can no longer get through – and your email connection to your customer has been severed. Chances are, the customer likely won’t even notice it’s happened.

This is a real problem for retailers, but it’s not all bad news. Much of this can be avoided by focusing on the content of email campaigns, and by better tailoring campaigns to individual customers. For example, Levi’s sends different emails to customers who purchased from them in the last 45 days and those who didn’t 90 percent of the time, according to the aforementioned study. Levi’s is catering to the different needs of customers and prospects in different parts of the sales funnel, thereby creating an opportunity to build engaging, long-term relationships with their brand – not just a one-time sale.

There’s no one-size-fits-all formula when it comes to the frequency of emails to send subscribers, but findings what’s best for your customers is well worth it. When it comes to purchases made as a result of receiving a marketing message, email has the highest conversion rate (66%), when compared to social, direct mail and other channels (DMA). What’s more, 81 percent of online shoppers who receive emails based on previous shopping habits were at least somewhat likely to make a purchase as a result of targeted email (eMarketer).

Email has the power to convert browsers into buyers more than any other tool out there, but only if it’s done right. So, remember – more isn’t always better, and good content is the best way to win customers.