Email marketing, when executed well, is a powerful and cost effective way to grow your base of loyal regular customers

Sending offers and rewards via email can help build customer loyalty, and can form the basis of a comprehensive customer loyalty program.
Email campaigns can be used very effectively to attract referrals and generate word-of-mouth among your target audience (its very easy for your customers to forward an email to their friends and colleagues, if theres something in it for them)
Email is an excellent tool for attracting quick responses to customer surveys and feedback forms allowing you to build your information base and customer profiles, allowing you to better target the right offers to the right customer groups.