Win with Lifecycle Marketing: A Crash Course in Subject Line Testing

Cory Smith
October 27, 2022
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Revenue from email starts with an open. Getting users to open emails is key to the success of any campaign. 

So, what’s the perfect subject line? Does it have an emoji? Is it short? Is it long? Does it include sale information? Does it have the recipient’s first name in it? Is it written in all caps? The answer is that it’s different for every brand. Users respond differently to different methods, and prompting an optimal open rate often takes testing. So how do you make a good subject line test? 

When we audit an account, it’s pretty common to see a lot of subject line tests. Whether you’re testing subject lines in campaigns or lifecycle emails, it’s a good idea – it should help you to find what works and what doesn’t. However, with the ubiquity of subject line tests, there are a lot of common pitfalls that we see that may actually be hindering your lifecycle marketing efforts.

Here are a few things to think about when diving into the world of subject line testing. 

First and foremost, it’s important that you understand how to use subject line tests. The goal of testing subject lines should not necessarily be to get more opens from a single campaign – the goal should be to find out how to write a good subject line for the future. So, while it may be tempting to test the subject line on every campaign you send, it’s more valuable to your lifecycle program to read results of positive tests to write better subject lines in the future. Here are a few guidelines to think about: 

Test concepts, not groups of words. Rather than just writing two subject lines and testing them against each other, think about testing two concepts against each other so that you can easily reuse the results of the test. There are a myriad of concepts that you can test. For example:

  • Inclusion of percentage off vs. Not including percentage off
  • Personalization vs. No Personalization
  • Specific Product Name vs. Product Collection Name
  • Inclusion of Price vs. No inclusion of price
  • Urgency vs. No Urgency
If you test concepts successfully, the next time it’s appropriate to use that concept again, you can select the winning concept to use in the future. 

Be diligent about reading results. It’s common for us to encounter subject line tests that have been running on a recurring lifecycle campaign for months or even years. It’s important to be diligent about finding where conclusive results have been found so that you can serve the better subject line (or concept) to users rather than the test. And if you’ve been running a test for a long time and results aren’t conclusive, it might be time to test some different subject lines!

Read the right metrics. It’s tempting to look at clicks or revenue to determine what subject line worked best, but if you’re designing tests correctly, those actions further down the funnel may not necessarily be affected by your subject line. Although email opens may not be the best metric for the ultimate success of a campaign, when it comes to subject line testing, that’s the metric that is going to get you closest to the truth for which subject lines perform best. 

Let campaign tests run for long enough to get results. It’s common in many Email Service Providers for real-time subject line tests to be a feature of the platform, where the two subject lines roll out to a small subset of users, and several hours later, the “winning” subject line runs to the remainder of users. We don’t love this feature for a variety of reasons, but perhaps most apparent is the impact of iOS14 on this type of test. Oftentimes, opens from Apple Mail come in all at once and affect the reliability of these results. In addition, the additional variable of time of day to the mix can have an effect on these tests, as traffic may be variable at different times of day. We recommend a 50/50 test where you can read the results to write better subject lines in the future. 

Work as a team. Even the most skilled copywriter could use a fresh set of eyes from time to time to avoid using the same tired language over and over. Bring in other teammates to help workshop subject lines if you can, and see what ideas they can bring to the table. 

Revisit what’s working best. Just because a certain kind of subject line works well today doesn’t mean that same kind of subject line will work again in six months. It’s important to revisit what you know to be true about your subject lines on a regular basis to ensure that you’re still putting your best foot forward. 

Right now, we’re zeroing in on the holidays, and knowing what kind of subject line will work best for your Black Friday campaigns is more important than ever for some businesses.

Make a solid test and learn how you can level up your email revenue with an innovative subject line testing program. If you’re looking to bring on a partner to help you strategize and drive better results during the holiday season and beyond, reach out to our team.

Cory Smith

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