The importance of a Call-to-Action (CTA) in a direct marketing campaign cannot be overstated. Next to the offer, it’s the most significant aspect of any mailpiece. It’s the how in the 5 W’s. You could have done everything right—used a paper stock and picked an envelope that stands out in the mailbox, created an eye-catching, aesthetically appealing format with dynamic copy that resonates with the prospect—and convinced them that, yes, they need to purchase your....