Savvy marketers realize that you can only achieve solid improvement on campaign elements that you actually take the time to measure. The great thing about email marketing is its ability to be evaluated quickly and effectively. If you're not evaluating past campaign performance, you’re missing out on key insights that can improve results.

Email marketers should regularly evaluate some core metrics. These include:

• Delivery rate
• Open rate
• Click-through rate
• Unsubscribe rate
• Conversion rate

Take an in-depth look at each metric and examine some ways you can improve your results.

Delivery Rate
As both Internet service providers and recipients tighten spam filters, more email messages are failing to reach customers. It’s been estimated that as many as 20 percent of permission-based email messages are mistakenly blocked.

Delivery rates can be improved in a number of ways. Getting your recipients to add your address to their address book certainly helps, as does practicing diligent list hygiene and carefully monitoring spam complaints. Surprisingly, these simple approaches are not yet widely adopted. For instance, Silverpop’s “2005 Retail Email Marketing Study” found that only two out of 10 companies requested recipients add the company address to their email address book. There’s a lot of room to improve this key metric for most marketers.

Open Rate
The marketing strategies that allow you to build a relationship with your customers affect not only open rates but also other metrics downstream. Research shows that the number-one factor that influences people to open an email today is knowing and trusting the sender. Presuming you have done everything to ensure a recipient wants your email--that is, you've obtained permission and are sending only relevant communications at an appropriate frequency--using your company or brand name in the "from" field and in the subject line will help increase the chance that your email will be opened and read.

Click-through Rate
The interactive nature of email marketing is one of its chief allures. With email, interaction comes when a recipient clicks on a link. As with so many other elements leading to success in email marketing, the relevance of the messages you send recipients can dramatically improve clicks. The key is personalized content.

Always address recipients by name. Try sending different offers to recipients based upon geography or demography, and use behavior (i.e. purchase history, email click history, visits to your Web site) as an attribute to guide campaigns.

Also think about the look and location of your links. Prominently-displayed hyperlinks and big action-oriented buttons, accompanied with compelling reasons for the action, make it clear to recipients what you want them to do. Further create a sense of urgency by giving reasons why they should act soon, such as limited availability, subscription expiration or “offer-ends” dates.

Unsubscribe Rate
If you see big jumps in the number of unsubscribes, your email program may be in trouble and it’s time to take a hard look at what you’re doing.

Separate new addresses from old and evaluate each list differently. If you’re seeing a growing number of new subscribers opting out of your email program, perhaps it’s because what you told them they’d receive when they registered doesn’t measure up to their expectations.

If you’re seeing customers who have been with you for some time begin to drop off, review past email messages and evaluate how fresh the promotions are and how compelling the merchandising is.

Unsubscribe rates can be lessened with appropriately constructed preference centers. Perhaps the frequency of emails is too high for some on your list. Offering weekly updates rather than daily bulletins, for example, could salvage an unsubscribe. Giving a choice of topics or product offerings can also help to maintain a relationship with customers and prospects.

Conversion Rate
Ultimately, the goal of your email campaign is to entice recipients to take some desired action, whether it’s to purchase a product, to sign up for a newsletter or white paper, or to schedule an appointment. The conversion rate is another important metric that gives you a read on how relevant your email campaign is to your customers. 

Getting recipients to do what you want is best accomplished when you make it clear what you expect them to do. Make the call to action obvious, and then make it easy for the recipient to comply.

Design landing pages with the thought in mind that it’s your last chance to entice a recipient to act. Further, make the conversion process easy by populating forms with the customer’s name, shipping address and other information at your disposal. 

Pulling it All Together
There's a wealth of information available to marketers from most email reports. If you begin focusing on one metric a month, you’ll soon have an invigorated email program achieving dramatically improved results.