“Look how FlightFox casually mentioned that 97% of customers would recommend the latest version of the service. That’s a stunning number, and it’s included in an email about a new blog post.”
Websites like TripAdvisor and Yelp thrive because consumers trust what other consumers think. Apply this principle to your email marketing. Casually mention statistics showing how many people would recommend your product, or meaningfully incorporate positive customer reviews in your emails.