Question: What data should I mine from my e-mail programs? Answer: E-mail marketing has become the bedrock of marketing in 2009 and will only continue to grow. Here are five metrics categories that represent big opportunities. 1) Performance: Most of us measure open rates, clicks and bounces. Some of us are looking at click paths and time spent per page. But don't forget insightful measures such as domain distribution; text and HTML viewing ratios; mobile phone viewership ratios; and name source performance. 2) Customer impact: Remember that the e-mail itself is not the goal. The real goal is to make an impact on your customers. Keeping an engaged and friendly recipient list lifts all performance measures, so track of the percentage of your list that has engaged over a period of time. Look at the ratio of newly registered to opted-out; your file should not be shrinking. Determine if your pass-along is getting you new registrants within the same domain or in new domains as a way to strengthen your message and offer strategies. 3) Marketing value: You're sitting on one of the most measurable marketing executions we have available. Think about the insight you can provide to your broader marketing initiatives with such data as product mix views and purchases; “firmographic” profiles of those who have engaged the most compared to those who engaged the least; promotion and incentive implications; customer needs via questionnaires embedded in your e-mails; and the mix of advertorial and editorial content. 4) Brand value: Using pre- and post-surveys, or those you place as content in your e-mails, you can deepen your understanding of your brand position among segments, sites or individuals. Build in ways to learn about opinion, cross-brand awareness and cross-brand opinion. This can be a very inexpensive yet hugely valuable addition to your program. 5) Business value: This is where the rubber meets the road. How many leads and orders did the e-mail drive? How much store traffic? Did you deepen your penetration into focused product categories? What was the pace and timing of your leads and orders? And of course, the ultimate question: How much revenue did you generate—and what was the ROI? Janet Rubio is chief insights officer at Engauge (www.engauge.com), a branding, digital and direct marketing agency.