With more active users than all other social media channels combined, it’s no surprise that email continues to be the most powerful marketing tool out there today. With its vast reach and limitless potential, you want to make sure that your email campaigns are performing as well as they should. You’re probably already tracking a handful of marketing metrics to measure the success of your email campaigns, but do you know exactly what these metrics mean? And more importantly, how can you optimize your campaigns to get those metrics where they need to be?

The internet is chock full of advice on email marketing metrics, so much so that it can be pretty overwhelming. While a lot of the info out there is helpful, it can also be contradictory and confusing. We came across a great resource by Chad White from Litmus and wanted to share it with you (see our version below.) Chad created a metrics “matrix” that breaks down all the important metrics based on campaign level, channel level and customer level.

We’ll be doing a three part series of posts that addresses metrics at these different levels. Part 1 focuses on campaign level email marketing metrics:


List size/ list growth rate


Are you sending to 50 or 5000 people? The overall “health” of your email list can tell alot about the direction your campaign is going. It’s extremely important to have a grasp on how many people are interested in your product and potential conversions and leads. An unhealthy email list can also cause a lot of problems down the road. Maybe a cutthroat competitor spammed your email list by signing up with a batch of bad email addresses. Unfortunately this is a common scenario, but you can combat these malicious marketers by keeping your email lists happy and healthy with a watchful eye.

Maintain healthy email lists by removing any bad addresses, visually scan email lists for common typos. It’s important to be proactive with your email list, as these small issues can often lead to larger headaches. More on this when we talk about bounce rates and delivery rates.


If your list is smaller, it’s likely that the customers on this list are more invested or interested in the product, which should result in a higher open rate. A larger email list can signify a broader and less interested consumer base, which usually will result in lower open and click through rates.

It’s also important to measure how quickly/slowly your email list is shrinking/growing. Is your list growing at a rapid rate? Awesome! But be aware that a larger list can also drive down other key metrics like open rate and click through rate. If your list is growing at a snail’s pace, that’s to say, little or not at all, you may want to take a look at your campaign strategy as a whole.

How can I grow my list?

Having a clear strategy for building your email list is essential to maintaining a successful online business. The first step in growing your email list is focusing on content. Customers will find your site because your content is strong and engaging and they will keep coming back for the same reasons.

  • Make sure your call to action is unmistakable. Think popups etc. (use cautiously)
  • Give users multiple opportunities to subscribe
  • Trade users something valuable for their email address (offers, hidden content)
  • Use social proof (join 18,000 subscribers…)

Open Rate


You’re probably aware that open rate is tracked using a unique embedded tracking image or pixel and when the email client requests the pixel, this is when an “open” is recorded. For the email to be counted as an open, images must be enabled OR the recipient must interact with the email by clicking on a link in the email. There is some controversy with this metric and many marketers feel open rate does not give an accurate picture of real data because of these measurement flaws.

Because many people use image blocking software, sometimes an email is opened without being counted, hence some of the controversy. Open rate is a difficult, but important metric to keep track of in your email campaigns.


As we know, even if an email was opened, there is no guarantee that this same email was actually read. On the flip side, if a customer’s settings are set to “images off,” the email could be opened and read and, sadly, never recorded as such. An ESP will also record an “open” if the email is selected simply so the recipient can delete it. You can see how a true open rate is obscured by these many moving parts.

We can also further break down the open rate into the number of total opens vs. the number of unique opens. For example, if a customer is opening the same email 10 times, this is a somewhat different scenario than if ten different customers were opening an email.

Unfortunately your open rate is never 100% accurate, but it can give you an overall idea of what/how many emails are being open and/or read. Open rates can also gauge the effectiveness of your email’s “from name” and subject lines.

Because of difficulty measuring the success of an open rate, one cannot rely on open rate alone to measure the success of a given campaign.
Quick tips on how to improve open rate for eCommerce:

Brand your messages

    • People are more likely to open emails from companies they love.

Extend your content range to engage

    • Perhaps customers are not opening your emails because they know that you’re always trying to sell them something. If that’s the case, we don’t foresee your open rates improving – customers are now very aware of marketing techniques. Instead try to engage them with different content. Recipes, advice, how-to’s, etc can help diversify your content, plus who’s to say you can’t throw some self promotion on those emails, too?

Strengthen Your Subject Lines

    • This perhaps is something we talk about too much, but for good reason. Every other metric is dependent on whether an email gets opened or not. Use testing to strengthen your subject lines and beef up your campaigns. Once you know what gets your customer’s attention, you can implement the changes that will get you an open and not a one way ticket to the trash bin.

Know Your Audience and Segment

    • Not everyone on your lists are as interested, or as engaged with your product as you’d like them to be. So why send to people who won’t open? Instead, use segmentation to learn how your customers behave (with your campaigns and/or through their purchase activity) and what types of campaigns they will interact more with. This will help you create a more engaged audience–and allow you to know who is more likely to open, click and buy.

Count your emails

  • Sending too many emails (or too little) can hurt your open rates. Look at your marketing strategy as a whole and count the number of emails you’re sending per month – in total. Then come up with a testing strategy where you can test whether sending more emails (or less) will increase open engagement. You can also give your customers the option to pick and choose how often and the type of emails they want to receive. This point may be the best option since customers are pre-segmenting themselves by selecting to be in certain campaigns that are of real interest to them.

Click Through Rate (CTR)


CTR is a measure of the number of recipients that click on any given link within your email.
When a recipient clicks on a link within your email, this is counted as a “click.” Much like open rate, many people find unique CTR a more useful measure of success. Even if a recipient clicks on a link multiple times, it will only be counted as one click, allowing for a more accurate picture of your customer’s engagement.

So what is considered a good click through rate? CTR’s can fluctuate drastically depending on industry, content, and segmentation. Usually, the entire goal of an email itself is a click, so a high CTR means that your campaign is right on track.


Your CTR allows you to measure how effective your campaign is. More often than not, B2C campaigns tend to have lower CTR than B2B. If your CTR numbers are pretty handsome, then you can high five your marketing team. If not, you can improve them.

CTR comes with several variations, though the most common and perhaps useful– is when you adjust your CTR by removing the impact of the open rate in order to measure just how your copy and CTAs are working together.


Another useful variation of CTR comes from diving click-throughs by messages sent, instead of messages delivered. Moreover, you are also able to use the unique number of click-throughs (by different users) and divide that by the total number of messages delivered. This will make sure that you are measuring the clicking impact that occurred within the number of emails that actually made it to a customer’s inbox. Regardless of your CTR formula, you must make sure that such is applied to all of your campaigns so that you have a uniform way to analyze campaign data.

So how can you improve your CTR? Let’s start with the basics:

What is your main CTA–what do you need your customers to do next?

    • Make sure that there is a clear CTA in your emails. Whether you want to get customers to purchase something, read your blog, find out about new products, etc., your customers won’t know what to do next unless you tell them so by giving them direction, you’re helping to improve your CTR.

Is it possible that your content is cluttering your CTAs?

    • Can they find your CTA? If you have more than one link you’d like them to click on, are these apparent? Customers will not click on something they don’t know they can click on so make sure that your links are styled in a way that they are evident and functional.

Are your emails mobile responsive?

    • With mobile opens increasing, most customers won’t bother to go through emails that are not mobile friendly. Your content and CTAs may not be showing in a visually appealing or even functional way, lessening the chances that they will be clicked and interacted with.

Do you have bulletproof buttons?

  • If you are using images as your CTA’s and your readers are blocking their images, your CTA’s will never be seen. Litmus has a great post on how to code buttons that will work everywhere, every time.

Click to Open Rate (CTOR)


The click-to-open-rate has been around for quite some time, however there is renewed interest in this metric as emphasis is increasingly being put on user engagement. Most email marketers focus a large part of their efforts on open and click through rates, Sadly, many ESP’s don’t even display this metric, but that doesn’t mean you shouldn’t be measuring it. We get the click to open rate or CTOR by dividing the number of unique clicks by unique opens and expressing this as a percentage.


CTOR tells us what percentage of recipients that opened the email actually clicked on a link, so it can be a very useful indicator of your customer’s engagement with the email content.

“Every aspect of testing should be focusing on the click-to-open-rate.”
Dain Hanson, Co-Founder of CYT Marketing.

Some analysts argue that CTOR is a weak metric to measure because the unique opens on which it is based are never accurately recorded. However the importance of CTOR cannot be overlooked as it provides valuable information about your customer’s expectations before they open your email and what actions they take after. CTOR measures your customers reaction to the email content itself. A low click-to-open-rate can reveal inconsistencies with your customer’s expectations and what you are actually delivering to them. Did your subject line promise them one thing, but then upon getting to the email’s content, they were met with something entirely different?

So what is a good click to open rate? With any metric, it can depend on a number of factors, including industry, segmentation, etc. MailerMailer found that industries with the highest CTOR include Staffing and Recruitment, Law Enforcement/Security, and Deals and Coupons rounding out the top 3.

Here are a couple of things you can do to improve CTOR:

  • Run A/B Split tests on your next campaign to find out what’s working and what’s not.
    Test for optimal time of day to send.
  • Based on the information we learned on TEDC15, the best day to send is early Monday morning–think 6 am.
  • Test several different subject lines
  • By doing this repeatedly, you will get to know what is the best subject line style, tone, etc. to draw your customers into your emails.
  • Test different CTA styles
  • Are your call to actions better as buttons, or would they work as links inside your copy? Maybe, even, a combination of those two. Though remember that you want to keep one main purpose – a known action you want your customers to take next – for all links you use.

Mobile Desktop Opens and Mobile Clicks


It should come as no surprise that an increasingly high percentage of emails are opened and read on a mobile device. If you’re anything like us, and consider your mobile device as simply another bodily appendage, chances are you are opening quite a few of your emails on your phone. Again this varies widely by industry, but it can’t be denied smartphone usage is changing the email marketing landscape at a rapid pace. Indeed, some studies show mobile opens to be as high as 70% in some industries (pre-2011 it was consistently under 10%)


So how does this affect how your customers engage with your email content? Naturally, marketers are spending more time and money on mobile email marketing, and must somehow measure the success of their efforts.

As the number of mobile users continues to increase, you want to make sure that your campaigns are optimized for mobile by coding them accordingly. We talked about this on our previous post about the lessons learned from TEDC15, but it’s important to know that there are several approaches to coding emails responsively:

Making sure your emails are being developed for both desktop and mobile is important and should be a prominent part of your marketing strategy. Emails are sent to the customer’s inbox, and now that inbox is constantly changing every time an email is opened, viewed, clicked, etc.

Spam Complaint Rate


Fortunately (or unfortunately depending on who you ask) customers have the power to report something they don’t want in their inbox. If your customers are clicking the “report as spam” button in your email, you’ll want to remedy the situation ASAP. These clickers can damage your name as a legitimate marketer and cause more headaches down the road with your ESP. Avoid spam complaints by only sending relevant content to customers who have agreed to receive it in the first place.

  • Avoid sending from a third party.
  • Be honest in your subject lines.
  • Keep your email list updated.
  • Send from a consistent address (do not use “noreply” etc.)
  • Keep your unsubscribe link easily accessible.

Do you know that some emails go to spam without someone sending them there? Here’s why:
Every ESP is using different guidelines in filtering spam, and even permission based emails sometimes get sent to the spam folder. ESP’s don’t make public their individual filtering rules as this would make it easier for spammers to get around them. This makes it all the more difficult for legitimate marketers like you to stay out of the spam pile. However if you are true to your content, honest with your customers, and avoid gimmicky copy, you should be able to steer clear of the dreaded spam folder.

Unsubscribe Rate


It’s generally accepted that a good unsubscribe rate is below .5%. Keep unsubscribe rates low by maintaining a clean email list. Don’t spam your customers. Regularly review content for potentially “spammy” or offensive content. Also keep your unsubscribe link visible, this may seem counterintuitive, but with an easily accessible unsubscribe link, you prevent further frustration and leave a lasting impression as a fair and reputable sender. Plus, it will save you countless of emails back and forth with your customer service to get customers unsubscribed. Less friction means happier customers – even if they don’t want to receive anymore emails.


How to reduce your unsubscribe rate:

    • Create value. People won’t unsubscribe from your emails if they see a take-away from the offers, newsletters, etc. that you’re sending.


    • Be consistent. Why did a customer unsubscribe from your emails? Perhaps they were bombarded by too many and opted out. However it’s also possible that they hadn’t heard from you in awhile and just decided to unsubscribe. The key here is to be consistent with your pace and timing to avoid scaring off or forfeiting your recipients.


  • Let people know that they can opt-out. This is more than just adding an unsubscribe link. Perhaps, you make it obvious on the first email of your campaign that customers can opt-out of receiving offers, newsletters, product notices, etc. Again, you are helping to filter customers who are engaged in order to get your data from customers who want to be part of specific campaigns.

Email Campaign Success


Conversion rate is often seen as the most important metric to look at when measuring the success of a given email campaign, and for good reason. Conversion rate is the percentage of recipients who clicked on a link in your email and then went a step further and completed a desired action (purchasing a product). In a few words, the total campaign response. Turning browsers into buyers is the ultimate mark of success in your email campaigns.


Conversion rate is influenced by factors outside of the original email. If your numbers are falling below you conversion targets, you might want to take another look at what is in between completing a purchase, making a new purchase, etc. If customers click but then don’t go through with a purchase, quality issues with your checkout process might be what is hurting you. Perhaps, shipping costs are not clear, or maybe customers have too many fields to fill in order to make a single purchase. Many of these issues are more internal than you think.

Take a look at this chart from MarketingSherpa that gives average conversion rates by product type.


A way to create even better data is by dividing the number of actions taken (conversions) by the number of click-throughs. Perhaps, within one campaign, you have customers who bought more than once just by being influenced by the emails you sent them. Thus, data like this might help you in the future to know which customers are engaging with your campaign the most.

Quick win to improve conversions:
Frame your campaigns in order to create a compelling reason to act upon your emails. Here you can use copy and imagery to solidify your CTA’s, create better CTR and engagement to potentially increase your conversions.

In Brief:

It’s evident that email marketing is more powerful than ever, and continues to grow in scope as technology evolves. It still offers the highest ROI of any channel and can reach the largest amount of users. Still, how we measure the success of any campaign is open to interpretation as marketers have long been faced with the challenge of a lack of uniform standards for email metrics.

With so much going on in your campaign already, it can be difficult to keep track of all the numbers and percentages flying around, however these metrics are an essential component of any campaign and cannot be overlooked. From the size of your email list to how many people purchased your product, each metric has an integral role in determining the overall health and effectiveness of your email campaign.

Stay tuned as we continue our series on email metrics with channel-level and customer-level metrics to help you get to the next level in optimization.

Jenilynn Hartnett
Jenilynn is a freelance writer and editor for Rejoiner.com. She is originally from Boston, MA and is curious about the world of email marketing and everything inbox related.