How To Test And Optimize Email Campaigns

How To Test And Optimize Email Campaigns

How To Test And Optimize Email Campaigns




In this article, I  will take a look at what email testing is, what tests you should perform on your campaigns and what metrics you should track. We will also look at optimizing emails and how to minimize the number of bounces and unsubscribes.

Email testing and optimization is something you should continually be performing on your email campaigns, this will help improve your emails which will lead to more opens, clicks and conversions.


Testing your email campaigns before launch is a vital step in email marketing. Ensuring your email renders correctly in all email clients and devices and loads quickly for users will help drive opens, clicks and conversions.

Utilizing various email testing techniques will help optimize your email marketing campaigns. Testing subject lines, from names, content, images, time of day, etc. will help you better understand your email audience.

Types of testing include:

  • Seed testing: A list composed of co-workers, friends or family that will help you to test your email before launch. Include at least 5 recipients but the more the better and try to find people that use different email clients and have different mobile devices.
  • Rendering testing: Tools such as Litmus, allow you to send your email to a test email address and preview your email in a variety of email clients and devices. This is great for showing any rendering issues that only happen in certain clients.
  • Load testing (images and text): When a user opens your email, all the images in the email will be downloaded. If your email contains multiple images or the images are large file size, then the email may be slow to load for the user, especially on mobile devices which have slower internet speeds.

Litmus is one of the most common email testing tools on the market, It is a paid service that offers a wide variety of testing tools to use before you launch your email campaign.

Litmus allows you to send your email to a test email address and from there Litmus will:

  • Show you your email in 70+ apps and devices
  • Validate all links, images, and tracking
  • Test the email load time
  • Allow you to build emails with their editor
  • Provide analytics on how your campaign performs


Litmus isn’t the only email testing tool on the market. Other email testing tools which offer similar features include Email on Acid, Return Path and 250 OK. Here are some of the features they offer:

Email on Acid

  • Testing & rendering: Here you can test your emails and see how they preview across mobile devices and tablets. It highlights and resolves potential code issues in your links, images and email copy style. It also spams tests to ensure email deliverability.
  • Editor: With the email markup feature, you can build, edit, preview and optimize your emails while also enabling the ability to comment and share email previews. It also hosts an image library so you can access and reuse images across your email campaign.
  • Analytics: This feature offers analytics on email engagement, whether your emails have been opened, what geographic location they were opened at, how much has been read and on what devices. This feature also enables you to track your email campaign’s success on a daily basis and records behaviour in real-time.

Return Path

  • Inbox placement
  • Certification: With Return Path, providers acknowledge you as a safe, reputable company and in turn, your email program receives reduced filtering at major mailbox providers. By following the program’s proprietary standards, it gives you a strong chance of your emails reaching more of your subscribers’ inboxes. Return Path monitors your email performance and adherence to these standards.
  • Reputation Monitor: If your IP has a poor reputation, your mail is less likely to reach the inbox. Reputation Monitor removes the mystery of your IP reputation by revealing how mailbox providers rate you as a sender using sending score, which is a credit score for email reputation. This feature also provides corrective advice to improve your sender score.
  • Email Validation: Clean your subscriber list of invalid emails. It verifies email addresses in real-time at the point of capture to reduce invalid sign-ups and it helps to reduce your bounce rate.

250 ok

A platform empowering data-driven senders with real-time insights into deliverability issues, reputation, user-level inbox engagement, and Domain-based Message Authentication, Reporting and Conformance (DMARC). The feature set includes 24/7 blacklist monitoring and customizable alerts, global spam trap coverage, seedlist optimizer, DMARC deployment and monitoring, out-of-the-box integrations with Litmus and Email on Acid, and more.


Now let’s take a look at some of the metrics you should be paying close attention to when testing your emails before launch.

Metrics that drive open rates:

A.Subject Line: the subject line is what drives recipients to open the email. It’s one of the most commonly tested components of an email and often used in an A/B test which we will be taking a look at shortly.

B.From Name: the from the name is the name that appears next to the email address, it’s different to the email address the email is sent from. In Gmail, the from name appears at the top of the email e.g. in the image above the from the name is ‘Digital Marketing Institute’.

C.Pre-header: this is the text that appears underneath or next to the subject line. You can define the pre-header in the code of your email or the first piece of text within the email body copy will be used. The pre-header text should be used as an extension of the subject line but note that not all email clients display this.

Metrics within the email:

D.Calls to Action: These are the links within your email. Often emails can have many links so it vital all are tested.

E.Social media icons and links: If these are included in your email, ensure they all link to the correct social media page.

F.Unsubscribe link and address: Make sure your email includes these and that the unsubscribe link works.

Other items:

G.HTML vs Plain text email: While the majority of marketing emails render the HTML of an email, some devices and screen readers use the plain text version of the email. It’s important to test both versions and make sure the content in both are updated together.

H.Personalization: Does the email have any personalization, such as using the recipient’s name in the email? If so, ensure the name is correctly being pulled into the email from the contact database and if there is no name that it still looks OK.


A/B testing, also known as Split Testing, is a method of comparing two versions of an email against each other to determine which one performs better. A/B testing is an experiment where two or more variants of an email are shown to users at random, an analysis is then used to determine which variation performs better for a given goal such as opens or clicks.


A/B testing can be used to test almost any element of an email, but only perform one test at a time to get accurate results.

In the above scenario, we are testing two emails which are the same but have different call-to-actions. To see which gets the most clicks, we send 20% of the audience each email and wait 1 hour to review the results. The winning email is the one with the most clicks. Then we send the remaining 60% of the audience that email.


A/B testing allows companies to make careful changes to their emails while collecting data on the results. A/B testing can be used regularly to continually improve a given metric, such as open rate over time.

Here are some of the best practices to follow for A/B testing:

  • Only test one variable at a time: This will give you the most accurate results as if you make multiple changes it’s difficult to see what change improved the testing metric.
  • Split your groups equally and randomly: This will help determine the winning email as there is no bias in the testing groups.
  • Test early and test often for best results: By testing early and often you can continually improve the testing metric over time.
  • Test as large a sample as you can for more accurate results: If you use a small test group, it’s easy for the metrics to be skewed due to normal variation. Try to include as many recipients as you can in the test.
  • Trust the data collected, not your gut instinct: If you prefer the blue CTA but the red variation performs better, go with the red one!


A/B testing is one of the most common testing methods in email marketing as it’s quick and easy to implement. There are many advantages of A/B testing emails including:

  • A better understanding of each segment: By continually testing, over time you will begin to see what type of content/format each segment prefers.
  • Determine the best subject line: Testing two different subject lines for your email on a subset of the audience will help determine which one to use on the larger audience for the best open rate.
  • Improved content: You can perform small changes for each test, and the end result will help improve the content in your email.
  • Increased conversion rates and more sales: A/B testing will help to improve your open and click rate. The more users that open your email means the more users that can click the CTA in your email, which gives you the best chance of getting a sale.

Now we will take a look at reporting and some of the metrics you should be paying attention to and how to calculate. After every email send you should be looking at the campaign metrics to see how it performed.

  • Click-through rate: The CTR is the percentage of recipients who clicked on one or more links within your email. To calculate, you take the number of clicks, divide by the number of delivered emails, and multiply by 100. You can use the total clicks to get the CTR or use the unique clicks to get the unique CTR.
  • Conversion rate: The conversion rate is the percentage of recipients who clicked a link and completed the desired action, such as make a purchase. To calculate, take the number of users who completed the desired action, divide by the number of delivered emails, and multiply by 100.

How To Test And Optimize Email Campaigns


Here are two more metrics you should pay attention to and calculate after each email campaign:

  • Bounce rate: Bounce rate is the percentage of emails sent that bounced and couldn’t be delivered. To calculate, take the number of bounced emails, divide by the number of emails sent and multiply by 100.
  • Share/Forward rate: Share/Forward rate is the percentage of recipients who clicked “Share this” button to post to social media. It’s calculated similar to CTR but you only use the number of clicks on the share/forward button. Take the number of clicks, divide by the number of delivered emails, and multiply by 100.

Here are two final metrics you should keep an eye on for your email marketing campaigns:

  • List Growth: This is the overall growth of your subscriber list. While this is a relatively simple metric, the more subscribers you have the bigger of an audience you have to market to. (As long as you keep your list healthy). To calculate, just count the number of new subscribers you get per week or month.
  • Overall ROI: The Return On Investment (ROI) of a campaign will show you whether the campaign was worth running. To calculate, take the additional amount of money made from a campaign, subtract the amount invested, divide that by the amount invested, and multiply by 100 to get the percentage return on investment for the campaign.

The metrics we just covered all relate directly to the email but they are not the only metrics you should be monitoring.

It is also important to monitor non-email engagements such as:

The recipient may not have clicked in your email, but because they read it this may have prompted them to log in, make a purchase etc.

While the email campaign goals might not be any of the above, they can still contribute.


As we saw in the section on campaign delivery, the last step in an email campaign is analyzing your results after you have sent your campaign and collected data. The Mail Chimp reporting feature contains campaign data on clicks, opens and total revenue from the campaign.

  • Recipients: the number of subscribers the campaign was sent to
  • Delivered: date and time the campaign completed sending from MailChimp servers
  • Open rate: percentage of successfully delivered campaigns that have been registered as an open
  • Click rate: percentage of successfully delivered campaigns registered as a click
  • Industry opens & clicks: the average percentage of opens or clicks campaigns in the selected industry set for your account


Action Point

I know you might agree with some of the points that I have raised in this article. You might not agree with some of the issues raised. Let me know your views about the topic discussed. We will appreciate it if you can drop your comment. Thanks in anticipation.



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About Adeniyi Salau 889 Articles
I am an IT enthusiast and a man of many parts. I am a Certified Digital Marketer, Project Manager and a Real Estate Consultant. I love writing because that's what keeps me going. I am running this blog to share what I know with others. I am also a Superlife Stem Cell Distributor. Our Stem Cell Products can cure many ailments.

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