Customers don’t have the patience to sort through cluttered inboxes. They’re inundated with marketing messages on a daily basis, much of which they never signed up for in the first place. According to the International Telecommunication Union, 80 percent of global e-mail traffic can be classified as spam. Additionally, the average email open rate among all industries falls between 19 to 25 percent, meaning that a large percent of subscribers aren’t even bothering to click the subject lines. The fact is, however, that email marketing is one of the most effective ways to target customers.