Email Conversion Rate Optimization

How influencing “little” numbers in your funnel can make all the difference

This is the ninth and final chapter of the HubSpot Academy Email Marketing Certification course, adapted for Medium. Sign up for HubSpot Academy to learn inbound marketing and sales for free. Access cutting-edge online courses, tools, and community to grow your business, and your career.

Chapter 9: Email Optimization and Testing

By Andy Francis

You might be asking, “Why do I need to optimize? Surely everything I’ve learned so far about email marketing is enough?”

You’ve laid the foundation to become a pretty talented email marketer by reading this email course, but if you want to bring your email game to new heights, learning how to test and optimize will ensure you get the most out of your email marketing strategy.

Did you know that that 83% of marketers are doing little to no optimization in email marketing? (

This means that most marketers are not spending time improving one of the most important marketing channels, and that you can enjoy an edge if you learn how to test and optimize your emails.

As with everything in online marketing — from image selection to ad copy — testing your emails is worthwhile as it measures the actual behavior of your unique database. Your findings will be much more accurate than subjective assumptions of what a “good email” looks like.

In turn, this means that your email will perform better, and have a positive effect on your overall marketing metrics. Things change. People change. Technology changes. Optimization will keep your emails performing at their best no matter how things change.

Let me tell you a little bit about conversion rate optimization (CRO). The purpose of CRO is to remove assumptions and opinions about the problems in your funnel, and focus on what user behavior data is telling you. Instead of saying, “I’ve got a 20% clickthrough rate,” you could say “80% of people aren’t clicking through on my email. Why?”

You have now discovered an opportunity. The next step is to develop a hypothesis and perform a test. Hopefully, you’ll discover a way to make your email perform better at all stages of the buyer’s journey. From visits to customers, it is very likely that email marketing played a part in getting them from the top to the bottom. At each lifecycle stage, businesses have multiple touchpoints with the lead through email.

At the lead stage you might send some educational content on your industry topic. At the opportunity stage, you might send a relevant case study and a link to your pricing page. And so on.

Email is a very special channel. It is opt in, direct to people’s inbox, and holds huge potential if done right at all the lifecycle stages of the buyer’s journey.

So, what is optimization?

Optimization is about making data-driven decisions throughout the entire lifecycle in order to widen or plug holes in your funnel. Assumption- or opinion-based marketing is not going to win in modern digital strategy. The way people interact digitally with your business changes rapidly from year to year, and optimization helps you to be agile with your unique database of contacts. It helps you develop email marketing best practices tailored to your business, and your business only.

Marketers tend to believe that success in email marketing comes from constantly growing the email list in order to make up for contact database decay (which is on average 22.5% of your list year-over-year). What if you used some of that time figuring out how to keep that email database more engaged and active? You spend all this time and use all these resources on getting that contact into your database. Why not find out how to upsell, cross-sell, or retain them at better rates?

So that brings us to the contacts who are dropping out of your funnel. Why don’t they want to hear from you any more? A survey by Constant Contact asked people why they opt out of email, or mark it as spam, and discovered that:

- 69% of people are getting too many emails, and 
- 56% of people say the content in the emails is irrelevant.

Both of these friction points can be solved by email optimization.

What if I told you that you have the power to increase your company’s sales by 100% … by simply doubling your email clickthrough rate?

You’d probably look at me and tell me I’m nuts, right? Well, influencing these “little” numbers in your funnel can make all the difference to your business. By focusing on improving email open rate and clickthrough rate, you can get double the number of people to take action.

Remember, the people on your email list already opted in to hearing from you. They’re waiting for you to send them something that makes them interested, excited, or feel important. Optimizing is about identifying the best experience for your contacts, delivering it, and reaping the rewards.

We’re living in an era where people expect their online interactions to be relevant to them personally, and correctly rendered across multiple channels and devices. Do you know the difference between how effective your emails are if they are opened on a desktop computer at the crack of dawn versus having them opened on an iPhone at lunchtime, or a Samsung tablet at sundown? Do you have your list segmented into subsets by key contact data, in order to send them the most appropriate messaging?

Optimization is a process. Optimization helps you to understand the key behaviors that result in a desired action from your unique email list. It also helps you identify the key friction points for your list so you can remedy them.

For example, I found that sending emails to large corporate companies worked far better when no images were included. Remember, optimization is the foundation of your company’s own internal email marketing best practices, which are what you should be working to establish with every email you send.

Understanding how to look at your email marketing funnel with an optimization lens will help you to test and improve your conversion rates over time on the metrics that matter to your business. Your email marketing will become more powerful and you’ll get to know your database intimately (which is what online marketing is all about!).

So, to wrap it up — what exactly is email optimization?

  1. First, it’s about understanding key behaviors and interactions on the email channel that are opportunities for your business.
  2. Second, it’s a process that helps you to identify the key friction points in email marketing for your database so you can remedy them.
  3. Third, it is about objectively reviewing your email marketing to consistently come up with experiment-driven solutions to new challenges.

Now it’s time to learn how to get an email A/B test up and running. A/B testing means that you will have the original email in a test against a variation of the same email — with one change made — about which you’ll gather comparative performance data.

Remember the scientific method from your school days? Well, it’s just like that.

Setting up and running email tests involves 4 steps:

  1. Segmenting your database
  2. Identifying opportunities in your funnel
  3. Designing experiments
  4. Prioritizing the experiments

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Step 1 is segmenting your database.

Look at your email list. How have you segmented it? If you own an online shoe store, it might be segmented by gender. If you’re an insurance company, it might be customers with a basic plan and customers with a platinum plan. If you’re a university administrator it might be alumni, current students, and prospective students.

At the very least, you should have your leads and customers separated out. Essentially, good email optimization starts with a well-segmented — and clean — database. Your lists should reflect distinct personas. Each of these personas requires their own optimization. Make sure to suppress unengaged contacts from your segmented lists, as the data may get skewed and serve up inaccurate results. So, before going any further, get cleaning and get segmenting.

Optimization requires a minimum number of actions to be taken before a test is valid. So, do you have enough people on your list to run this test? An A/B test significance tool will help you determine how many contacts you need in advance of setting up an email test. Use this tool to predict your list size correctly:

Let’s walk through an example. If your email funnel conversion rates are:

  • 95% delivered
  • 10% opened
  • 0.5% clicked

And the A/B test significance calculator tells you that you need 500 clicks to get statistical significance, would you be able to do that with your current list size? Let’s say your list was 10,000 people; pop them into that funnel.

Looks like before you can run clickthrough tests, you should probably run some open rate tests to increase the volume. And if you’re going to run A/B tests, as well, then you must have enough people to potentially open and click both versions.

So, now you have a nice, clean, segmented list that is large enough to start testing your emails. Perfect. Let’s move on.

Step 2 is identifying opportunities in your funnel.

The core of CRO is to look at your data in order to find the weak points in a marketing funnel, figure out what is causing the funnel to narrow, think about a good solution, apply it in a controlled test environment, record the results, analyze the results, and make a determination on the efficacy of that solution. Just like the scientific method.

Before you send an email, you must follow these simple rules to make it optimized for conversion: Is the email going to the right person, at the right time, with the right message? Does the contact know how to take the action you desire in the email? Does the contact trust you enough to take that action? Your emails need context, clarity, and credibility.

A/B testing is a powerful methodology that can drive significant results for your email campaigns. It looks simple — and it is when you’ve had a little practice. But don’t jump to conclusions too quickly in your first few tries. You will need to spend time figuring out what exactly to test.

So, what are the testable elements of an email that affect open rates? Well, you’ve got:

  • Number of emails sent to a list
  • Day of the week
  • Time of day
  • Subject line
  • Preview text.

And what are the testable elements of an email that affect clickthrough rates? There’s:

  • Email body copy
  • Email body design/layout
  • Email body images
  • Email CTA
  • Email signature

So, how do you determine which of these elements impact your email marketing success the most?

This is where you need to jump into your email analytics. Can you determine a pattern that tells you why your open rate or click rate is lower than you want it to be? Is it because of the device your contacts are using to read email? Is it the time of day, or day of the week? Does a particular email template get better engagement? Do certain words in the subject line cause more or less engagement?

Once you’ve found a list of friction points (that is, places where your contacts are halting in the funnel) and fluid points (that is, points where your contacts are readily moving down the funnel) you can start to formulate your hypotheses on what is lowering the conversion rate at different points in your email funnel. A lot of optimization best practices only speak to the friction points. However, it is equally important to find out what is working well so you can apply those good ideas elsewhere.

Step 3 is designing your experiment.

Next, you are going to hypothesize what is causing the holes in your funnel, and come up with ideas on how to plug them. An important aspect of testing is to make sure what you are proposing is feasible. If you don’t want anyone to unsubscribe from your emails, don’t send ANY emails! Great experiment, right? Not so much.

When hypothesizing, you need to be creative but you also need to keep your ideas within the boundaries of reality. Adding a monetary incentive to the body of your email may improve the clickthrough rate — but legally, you may not be able do that. And would you be able to keep that up in the long run? These are the things you need to think about when hypothesizing a solution.

Example Scenario: My emails are not getting opened! How can I fix this?

  • Hypothesis #1: A lot of your contacts use Gmail. Your emails are ending up in the Gmail promotions tab rather than the primary inbox.
  • Solution: To avoid getting marked as “promotions”, you need to do the following. Check that your email sounds personal, rather than business-like. Reduce or remove images completely. Limit links in the email to one. Avoid using words like “buy”, “sell”, “discount”, and other sales-like language. You can use Litmus’s “Gmail Tabs” tool to check in advance if your email will end up on the promotions tab. See if applying those best practices helps your open rate.
  • Hypothesis #2: The subject line contains characters and words that are triggering the recipients’ spam filters.
  • Solution: Do not use emojis. Avoid exclamation marks and percentage signs. Remove sales-like words like “free” or “discount.” Closely align the subject line with what the email contains. You can use ISNOTSPAM’s tool to determine if your email is SPAM trigger-free. See if applying those best practices helps your open rate.
  • Hypothesis #3: Your emails are arriving at the recipient’s inbox at a time that does not suit them to open it.
  • Solution: You can use an analytics tool to determine when emails are opened most and start to target those times by scheduling your email sends. If you do not have an analytics tool, and you are sure of the common time zone your contacts are in, use logic. For personal items such as shopping or travel, aim for when they are likely to be at home. For business and education emails, aim for when they are likely to be commuting or on lunch break. Observe if applying these practices help your open rate.
  • Hypothesis #4: The subject line is not interesting or compelling in any way.
  • Solution: Use your in-depth knowledge about your persona, and remember how your email content applies to their stage in the buyer’s journey. Then, analyze your historical subject lines. What subject lines caused higher open rates? Are you sure it wasn’t because of seasonality? Can you determine a pattern of words or types of words that work well? You can also use the headline analyzer to determine the level of emotional connection with the subject line.
  • Hypothesis #5: The subject line is not optimized for mobile and does not sell the value of the email content within the restrictions of the screen.
  • Solution: If you do not have an email testing tool, simply send the email to yourself or your colleagues and have them open it on various devices. How does it look? What key words need to be visible?
  • Hypothesis #6: You send too many emails, so your contacts are less and less compelled to open them.
  • Solution: Reduce your email frequency for at least one month — preferably a business quarter — and observe if email open rates improve.

Step 4 is prioritising your experiments.

And now, deciding what to test first. Welcome to the PIE framework. (Who doesn’t like pie?) Well, here’s an optimization PIE for you. PIE is a system of determining what you should test first. P = potential, I = importance, E = ease. Which change would have the biggest impact on your email marketing funnel, and can it be easily done?

Let’s take the 6 hypotheses and solutions from the open rate challenge, and see how you could rank these tests.

When you are thinking about how to score your tests, think about what changes have the broadest impact. For example, your newsletter would rank higher than a one-off send, because it is a frequent email. However, a one-off invitation to a big event ranks high in importance because you’ve got limited shots at getting it right. So think about it this way — will the changes I make help with all of my email marketing, some of my email marketing, or a small part of my email marketing?

PIE takes away your action paralysis. Rank your proposed solutions in the PIE framework. Easy as … pie. Sorry.

Finally, it’s time to run an email optimization test. I recommend beginning with a regular and frequent send — something like a daily offer update, common transactional email, or a weekly newsletter. These are highly valuable business communications with lots of impact, and they are frequent enough to reach statistical significance.

So how long should you run your test? A common misconception is that you only have to send one or two emails to get a result. However, this could lead to an immature conclusion. One of the most common mistakes people make is ending a test too soon. If you simply ran an A/B test on one newsletter send, and you got a conversion rate increase of 20%, you can’t really claim that the improvement was due to your change. There are far too many variables at work, the content being offered in the email being the most obvious.

You need to choose one replicable change and test it over a number of these sends — preferably a business quarter. A/B testing is only effective if you change a single element consistently.

If you are testing for open rate, use the numbers of delivered and opened emails. If it’s click rate, use delivered and clicked. Record your results until you have enough of a sample to be confident that your test won.

So, what do you need to do to get a good email optimization test up and running?

  • First, make sure your contact list is clean, and segmented to persona and / or stage of the buyer’s journey.
  • Second, make sure that list is large enough to test with.
  • Third, analyse your funnel for opportunities.
  • Fourth, use the scientific method to hypothesise and design solutions.
  • Fifth, use the PIE framework to determine what to test first.
  • And finally, check that your results are significant when you’re done.

This is the ninth and final chapter of the HubSpot Academy Email Marketing Certification course, adapted for Medium. Sign up for HubSpot Academy to learn inbound marketing and sales for free. Access cutting-edge online courses, tools, and community to grow your business, and your career.

Chapter 1: Email Marketing and Your Business
Chapter 2:
Sending the Right Message with Lifecycle Marketing
Chapter 3:
Contact Management and Segmentation
Chapter 4:
The Components of a High-Performing Email
Chapter 5:
Email Design and Functionality
Chapter 6:
The Essentials of Email Deliverability
Chapter 7:
Developing Relationships with Lead Nurturing
Chapter 8:
Measuring Success With Email Analytics
Chapter 9:
Email Optimization and Testing

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