Email marketing is all about metrics.

Whether you’re a restaurant, hair salon, consulting firm, or nonprofit whose mission is to save a blue-spotted toad only found in people’s sock drawers, these numbers are the foundation of any email campaign. How many people are opening the emails? How many are using the content and going deeper into the site? How many are sharing the news with their friends?

Constant Contact’s email marketing tool shows you all of these statistics, but it doesn’t tell you which one is most important. That’s for you to decide. That’s why we brought together our managing editor, Martin Lieberman, and our senior content developer, Dave Charest, to talk about which metric is the most important to track.

What is the most important metric of email marketing?

Dave: I’m going to be a bit of a traditionalist and vote for clicks.

Martin: I used to say it was click-through rate, but these days, I think it’s the number of shares. That’s the metric that will tell you not just how interested your subscribers are in your content, but how “worthy” it is of being passed along to other people, and how widely it was spread. The goal of your email content now should be to make it both interesting and shareworthy.

What makes it more important than the other metrics?

Martin: I’m not a click-through worshiper anymore because it’s a different marketplace now than it was even a year or two ago. Your customers are doing the marketing for you. So you need to arm them with content they can easily pass along so others can discover all the great things you have to offer. Metrics like open rate and click-through rate — those just speak to the one customer who received the email. Sharing metrics speak to how wide your business or organization reaches beyond your mailing list.

Dave: I still believe clicks are most reliable metric. Here’s why: Opens tell a distorted story about your email. In order for an open to register in your stats it relies on a blank image file which triggers when a subscriber opens the email. But what happens when images don’t open because the reader is on a smart phone or is blocking images in Outlook? Nothing. You don’t get any credit for that open. On the other hand if a person opens your email many times that also becomes part of your stats. Not exactly the best indicator.

Shares may seem like a good metric, but again, they only tell part of the story. Readers can share your emails all they want, but you may never be able to tell if anybody else is acting on them. That’s why clicks come in as the most important metric. When a person clicks, you know you’ve spurred your reader to action.

How can email marketers use this metric – and adjust their strategies – to improve it?

Martin: For one thing, they should make sure they are sending subscribers good, quality content that a reader is going to want to share. Helpful tips or advice, something fun, or something unique to the business or organization. Then, the message has to be shareable, so including a Share Bar is key.

Dave: You’re able to test whether or not you’re creating a compelling call to action based on clicks. You can create a control piece to test against and make adjustments to find the strongest words or phrases. You can see what happens if you add more or less copy. The click metric offers you many options to fine tune what works best for your audience.

Another benefit is that if you focus on getting people to click, they’re more likely to click through in the future, especially when your audience knows they’re going to get something of value. You’re also able to see what your subscribers are actually interested in.

Do you think email marketers pay as much attention to this metric as they should? Why or why not?

Martin: Not yet. While many email marketers do create shareable emails, too many others aren’t taking advantage of the potential to have their messages seen by more people than they even know. As soon as someone sees how often their messages are getting shared, they’ll be encouraged to keep improving their content so it gets around to more people.

Dave: I would say the good email marketers do *laughs*. It’s important to note that marketing with clicks shouldn’t stop at the numbers. Once you’re getting the clicks you’ll want to focus on what’s happening in terms of conversion when they get to where you want them to go.

What’s the bottom line?

Martin: These days, sharing with social media is becoming increasingly important, but that doesn’t mean that email is falling to the wayside. Both are different flavors. If you mix them right, you’ll have the best possible recipe for an email marketing campaign, with the metrics to show for it.

Dave: Email is the original social media and you’re always going to want to know what people are clicking. So even if subscribers are sharing your emails with other inboxes or out in the social media universe or on a blog, you’re still going to be looking for the number of clicks to measure what happens.

Which metric do you think is most important? Share your thoughts in the comments section below.