1) The document discusses 21 challenges that marketers face when using email to power the customer experience. It addresses issues like getting internal buy-in, proving email's value, creating a seamless experience, understanding the right role for email, forgetting secret weapons, lack of marketing automation adoption, and knowing where to start. 2) It also provides tips on understanding customers by leveraging data from different channels, treating customers differently based on factors like age, joining customer touchpoints with email, and leveraging offline business strategies. 3) The document advocates for making customers feel special through rewards programs, extending experiences with reminders and useful information, and integrating email with apps to drive traffic.