How often and how many variations should you test your email subject lines?

1 Why test email subject lines?

Email subject lines are the first thing your subscribers see when they receive your email in their inbox. They can make or break your email performance, as they influence whether your subscribers will open your email, ignore it, or delete it. Testing different subject lines can help you understand what appeals to your audience, what triggers their curiosity, and what motivates them to take action. By testing email subject lines, you can improve your email marketing metrics and achieve your goals.

2 What to test in email subject lines?

There are many elements that you can test in your email subject lines, such as length, tone, personalization, emojis, questions, urgency, benefits, and more. The key is to test one element at a time, so that you can isolate the impact of each variable and measure its effect on your email performance. For example, you can test whether adding the recipient's name to the subject line increases the open rate, or whether using a question or a statement works better for your audience.

3 How to create email subject line variations?

To create email subject line variations, you need to have a clear hypothesis and a goal for your test. For example, you can hypothesize that using a question in the subject line will increase the open rate, and your goal is to achieve a 10% increase in the open rate. Then, you need to create two or more subject line variations that differ only in the element that you are testing. For example, you can create a subject line with a question (e.g., "Do you want to save 20% on your next purchase?") and a subject line with a statement (e.g., "Save 20% on your next purchase today!"). Make sure that your subject line variations are relevant, clear, and compelling for your audience.

4 How to run email subject line tests?

To run email subject line tests, you need to use an email marketing tool that allows you to split your email list into segments and send different subject line variations to each segment. You also need to define how long you want to run the test, how many subscribers you want to include in the test, and what metric you want to use to measure the success of the test. For example, you can run the test for a week, include 10% of your email list in the test, and use the open rate as the metric. Then, you need to analyze the results and compare the performance of each subject line variation. You can use statistical tools or calculators to determine if the difference between the variations is significant or not.

5 How often to test email subject lines?

There is no definitive answer to how often you should test your email subject lines, as it depends on your email marketing strategy, goals, and resources. However, some general guidelines are to test your email subject lines regularly, but not too frequently, to avoid fatigue and confusion among your subscribers. You should also test your email subject lines whenever you launch a new campaign, offer, or product, or when you notice a decline in your email performance. Testing your email subject lines can help you keep your email marketing fresh, relevant, and effective.

6 How many variations to test in email subject lines?

The number of variations that you should test in your email subject lines depends on the size of your email list, the confidence level that you want to achieve, and the complexity of your test. Generally, the larger your email list, the higher your confidence level, and the more complex your test, the more variations you should test. However, you should also consider the trade-off between testing more variations and reaching a conclusive result faster. Testing more variations can give you more insights and options, but it can also take longer and require more resources. Testing fewer variations can give you a quicker and simpler result, but it can also limit your creativity and learning.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?