Word of mouth communications and peer-to-peer dialogue often have a greater effect on customers, since they are not sent directly from the company and are therefore not planned. Customers are more likely to trust other customers’ experiences. Examples can be that social media users share food products and meal experiences highlighting certain brands and franchises. This was noted in a study on Instagram, where researchers observed that adolescent Instagram users' posted images of food-related experiences within their social networks, providing free advertising for the products.
Just like with any other form of advertising, you will need to hit people with your message more than once in order to maximize effectiveness. Your first send might pique their interest, but people are receiving mail at the same time they are getting home, and are facing many distractions. By consistently sending marketing messages, you increase the chance that they will convert.