The CMO's Guide to Email Marketing provides insights into how to maximize the return on investment (ROI) of email marketing. The survey findings show that email offers the highest ROI for marketers, with a 36:1 ratio. However, there are ways to increase this impressive number, such as regulatory compliance, adding resources to the team, and personalizing content. The report also highlights the importance of QA, A/B, and spam testing emails to improve ROI. Overall, these findings can help marketers make informed decisions as they plan and strategize their email marketing program.