The Importance of Email Testing


Email is one of the most effective digital marketing strategies with the highest ROI. It can be used to develop and maintain relationships with your members while keeping them informed in the quickest manner. We saw this in play over the last few months as credit unions needed a distribution method to communicate COVID-19 response updates. And there were many! Through email, they had the power to reach those members in an instant. 

Email marketing has the highest rate for acquisition and retention in comparison to organic search, paid search, and social media. So, if you’re looking for direct impact and reach, email marketing continues to be at the top of the charts.

As you continue to implement email marketing as part of your marketing strategy, it is important to understand how powerful email can be. According to Statista, in 2019, email users amounted to 3.9 billion globally with many checking their email multiple times daily. Sending emails with valuable, edited content is a great strategy to ensure optimized open rates. Additionally, it is highly important to know how those emails render across all platforms. If your members continually open your broken emails, wondering about the credibility of your credit union, you could lose those members and in return, lose revenue. 

Testing is critical 

So how do you avoid sending less than perfect emails to your members? 

TEST! TEST! TEST! Implement an email testing strategy to avoid any flawed emails being sent to your members. 

With more than 15,000 different possible renderings, an email that looks great in your Gmail on your desktop may look entirely different in someone else’s Yahoo Mail on their iPhone.

While testing emails requires extra time and money, it is well worth it. Research shows that email marketers that test the rendering of their emails saw an average ROI of 44-to-1, compared to those who don’t test, who saw an ROI of 38-to-1. 

Subscribers typically take only a few seconds to decide if they are going to read your email, so let’s look at why it is important to test all emails before sending them and review best practices for guaranteeing a great member experience.

Standards are different across ESPs

Email service providers (ESPs) all have their own ways for rendering HTML. This is because there is no set standard across ESPs. The likeliness of implemented standards for email is slim because technology would quickly surpass any set standards. Data and delivery change too quickly for every ESP to follow one set of standards. And unfortunately, the unwillingness of certain inbox providers such as Outlook and Gmail to support modern code means it falls on email marketers to work around them to develop good emails.

Furthermore, ESPs, devices, operating systems, and browsers are constantly being updated. If your email templates are not updated along with them, your email will most likely have broken or untracked links and skewed code that changes the appearance of your design. Through email testing, you can identify if updates have occurred or if any changes have affected the code and make revisions as needed. 

Broken, incorrect, or untracked links

An easier concept to grasp for why emails must be tested is email designs. While you typically have brand standards and may work off

404 error page template for website. 404 alert flat design.

templates to create emails, the design of your emails will change every so often (or at least, they should). According to a study by Litmus, 86% of brands go no more than two years before an email redesign. Any time a redesign occurs or any time you create a new email (even when using a template) testing is imperative for its functionality.

Sending emails with links to a 404 page (page not found) can disrupt member experience and lead to missed opportunities. Sending emails containing incorrect links, while not totally disrupting member experience, can still send the member to an unintended area of your website and ultimately discourage them from reaching their intended destination. Tracked links (such as those created using UTM codes, which modify the link to provide traffic info) are not member facing but are important for insight to accurate analytics. Broken UTM codes prevent tracking of member behavior. 

Verify that all the links within your emails are correct by testing and you will save your member experience, ensure intended destination, and correctly measure success of email campaigns and subscriber engagement. 

Best practices

Here are some email building best practices to avoid rendering issues:

  • Use an ESP

    If you don’t use an ESP to send an HTML email and you simply paste the HTML code into an inbox provider email, the code will render very poorly.

  • Use an email builder

    This will help you determine correct sizing and allow for fallback fonts and colors in case the email incorrectly renders the original font or color.

  • Use standard sizing 

    The standard email width is 600px, this size will be responsive with most inbox providers.

  • Use common web fonts in your emails

    Fonts such as Arial, Calibri, or Times New Roman have higher compatibility than others and a better chance of rendering across different devices, operating systems, and browsers. 

  • Choose a backup background color

    In the event that you use an image as a background, you will want to select a fallback background color. Some versions of Outlook and Windows do not support background images and many inbox providers have only partial support. 

  • Use bulletproof buttons rather than images of buttons or creating a button in email builder

    Buttons created in email builders often render incorrectly and look like a plain box. To work around this, marketers began using images of buttons, but this method is not a best practice because many inbox providers block images by default. Bulletproof buttons allow you to build buttons with a small snippet of in-line CSS and HTML. Even better, by using CSS and HTML the button will display even when images are blocked.


    There are multiple tools you can use to test emails during the development process such as Litmus or Email on Acid. These tools allow you to preview your email from various inbox providers, devices, and browsers in one location. You can also perform manual tests, but with this method there is almost no way to test all versions of how the email will appear.

There are many more best practices to execute that will help avoid improper rendering, but it is important to remember that there is no one-size-fits-all for proper email display. What you as the marketer can do is ensure that you execute these best practices through always testing your emails before sending. 


Your email address will not be published. Required fields are marked *