How to create a good email testing plan

If you’re sending emails out to a lot of people, it’s critical to have a good email testing plan in place.

Testing your emails thoroughly ensures that your emails will show up and display correctly in your recipients’ inboxes no matter what technology they are using. This article will help you understand what test plans for emails are and give you some tips for setting one up for your needs.

What is a test plan for emails?

Test plans for emails are carefully thought out documents that contain detailed instructions on what to test, how to test it, and the results of the tests. A test plan acts as a guide to keep you and your team focused on the right goals at the right time so you can conduct your tests quickly and efficiently.

For emails, test plans will include details about all the things you should test to make sure your emails are functional, error-free, and are sending the message you intend. There can be a lot of details to test. This is because the way your emails will show up in people’s inboxes depends on what email client, browser, devices, and settings they use, in addition to other parameters. Testing the most common combinations means you can fix errors and bugs your recipients might see that won’t show up in your email preview.

What things should I test in my emails?

If you’re not sure where to start when identifying what needs to be tested, consider what your goals are for the email and break down what needs to happen to meet that goal. You can also go through your email line by line and identify each component, and use that list to identify key parts to test.

The right things to test will depend on the email’s main goal, your audience, and other factors specific to your organization. We’ll discuss some examples of things to consider testing in the subsections below, but this isn’t an exhaustive list:

  • Images
  • Links
  • Spam filters
  • Dynamic content


Most HTML emails will include images. Images are important to test in your emails since there are several things that can go awry. When planning to test email images, some things to consider include balancing the image quality with file size, checking the image dimensions, having alternate text, and others.

Having the right image quality is important to make sure that your images look crisp, not blurry and pixelated. However, as image quality increases, so does the file size – and having large file sizes will make your emails load slowly. Some things to check include setting the image dimensions to the right size, using file types that are more efficient, and reducing file size through other image optimization techniques.

The right image dimensions will depend on the email’s design, but a good rule of thumb is to keep the width to 600 pixels or less, since most emails are designed to match that width. If your images aren’t taking up the full width of the email, you can consider resizing them to be smaller to further reduce the file size.

In addition, including and testing alternate text for images is especially critical for emails, since many email clients have settings to stop images from automatically downloading. If your recipient has this setting active, instead of seeing the images from your email, they will see the alternate text displayed. Alternate text is also important to improve the accessibility of your emails for people who use screen readers and similar technology.


Most emails will also have links somewhere in the email’s body or the footer to direct the reader to places on your website, reset passwords, link to social media, or other reasons. Broken links can prevent your email from working as intended and damage your professional reputation, so testing them before sending out your email is a good choice.

Some of the ways links can be broken is if they were spelled incorrectly, the address changed, or if there’s another problem with the place they are linking to. Some of these issues can require coordination between multiple teams to fix, so finding them early is helpful.

Spam filters

Spam filters are a constantly evolving defense that can block your emails from reaching inboxes. They aren’t perfect, and sometimes they block emails that your recipients want to receive. Running your emails through some testing to check if they’re likely to flag spam filters can help you tweak things before you press send.

Dynamic content

If your emails have dynamic content, or content that changes depending on user input or other customization, the chances are higher that there will be bugs that need to be worked out. Setting up testing for dynamic content can get complicated and require some creativity to foresee what problems might occur before your recipients find them. Testing the limits of user inputs and error messages is usually a good place to start.

If the dynamic content has branching options, mapping those options can be another helpful place to start. Each option is another thing to test to make sure it will interact the way it’s supposed to under many different conditions.

Tips to set up a good email testing plan

In the next few sections, we’ll go over some more general tips for creating a robust testing plan for your emails. Some things to keep in mind include the following:

  • Setting realistic goals
  • Documenting your tests
  • Getting your team’s input
  • Identifying software tools

Set realistic and measurable goals

Realistic goals are structured with your time and budget in mind. While it would be ideal to test every single combination of software, devices, and other technologies that your recipients might use, realistically that would take a lot of resources. It may make more sense to focus on the most important tests to run, and use the resources you have left to check what other details you can.

Setting good priorities for your email testing is easier said than done. One way to look at it is to consider all the things you could test and make a list of priorities based on that. Another way is to focus on the end goal for your email and work backwards on what testing to prioritize from there.

Creating measurable goals for your testing is a key way to keep your testing well-defined. If tests can’t be measured, there isn’t much point in running them. Having something clear to measure will give you a way to see what has improved over time, what needs to be fixed, and what tests to prioritize in the future.

Document your tests

Your test plan should include how and when to document the results from your tests, including who on your team is responsible for the documentation process and where the documents can be found. Some things to include in your documentation are:

  • Your testing goals
  • What you are measuring
  • Each testing step
  • Who is involved in testing
  • How the documentation will be stored and updated

Your organization, team, and overall goals will define the requirements for your documentation. It’s important to regularly revisit your documentation strategies to see if there are places to improve.

Get input from your team

One source of information on setting up a good testing plan and what documentation is required is the people conducting the testing and drafting the emails. You can also get input from people working in customer service or other customer-facing roles, since they may have some valuable information on what your email recipients are seeing.

Checking in with your team on what is working and what could be improved is a great strategy for making your individual test plans better, since every team will have different needs and goals for testing.

Identify software tools to use

Your test plan should also include details on what software tools to use to make testing faster and more effective. There are many software solutions out there for improving email testing, including many geared towards setting up automated email testing. Automated email testing can save tons of resources once properly set up and maintained by an expert. Choosing software that is flexible and customizable can be a good starting point.

Mailosaur is an invaluable addition to your email testing toolkit, offering a range of features to streamline and automate the testing of email functionalities. With Mailosaur, you can conduct thorough tests, ensuring the seamless operation of email workflows within your application.

Get help testing emails

Mailosaur offers software tools to help with all kinds of email and SMS testing, including tools to generate custom email addresses and phone numbers to simulate what your customers will see and stress-test your systems. Our software can be integrated with a lot of popular choices for email testing, like Selenium and Cypress. Please reach out to us if you have questions about how to create good email test plans or set up email testing!