Email service provider Mailchimp has released research concluding that the more links an email contains, the higher the click-through rate. Why then do so many retailers send single topic, post-card style email campaigns? There’s nothing wrong with sending an email on a single topic if you’ve properly segmented your audience. But if you haven’t, you’re gambling that the majority of your list will be interested in the product you selected to highlight. In general, try to include as much product content as possible in an email to boost the likelihood a customer will see something that resonates with them.