Email Marketing is a key function to increasing your sales, as it's the most direct form of contact with a potential consumer. Like all forms of marketing, it's important to know what your ROI will be upon implementation, which you can find out with this Email Marketing ROI Calculator.
http://www.bplans.com/business_calculators/email_marketing_roi_calculator
http://www.bplans.com/business_calculators/email_marketing_roi_calculator
