With the vast array of analytical information available in the email channel, the measure of success sometimes gets a little muddied—especially when there are multiple stakeholders claiming ownership of overall success. But then again, what is overall success? For most marketers, it's revenue; in particular, increasing revenue by improving your program. For others, it may be subscriptions or other desired actions or conversions. What's important is there's an overall goal measured—not campaign by campaign, but as an overarching result over time that can be compared against the same period in the previous year or to the previous period.