Resources Hub » Blog » 5 Email Tests You Need to Run Right Now for Better Results

Article first published July 2015, updated May 2019

As a modern marketer, there are a million demands on your time and testing your email marketing campaigns may often end up relegated to the bottom of your list.

But testing doesn’t have to be time-consuming and the opportunities you can uncover to improve and optimize your results can be priceless.

In this post, I’ll break down five email tests you should run right now to get better results, plus share a few common tips for testing.

Why test?

Testing allows you to compare and contrast different elements of your email campaigns to see how they impact your subscribers’ reactions to them. You can form a hypothesis about what you think will occur, and then formulate a test and find out what really happens.

For example, maybe you’re not thrilled with your email campaign click-through rates and want to increase them. We recently noticed that some of our click-through rates were plateauing, so we decided to run a few tests to see if we could boost them up. We wanted to see if we could use our Dynamic Content feature to increase the click-throughs.

By using some simple segmentation and custom imagery that appealed to each individual recipient of the email, we were able to get a 13% increase in click-throughs and drive thousands of extra visitors to the content in the campaign.

This lift in click-throughs prompted us to test even more things, and we ran an A/B test of a new design of our blog subscribers email against the old one. Guess what? We got a 127% lift in click-throughs just by using a more visually appealing design.

As you can see, you can gain a ton of actionable insights from your email tests that can directly affect the performance of your campaigns. So let’s get into the 5 elements you should be testing.

5 elements of your email campaign you should be testing

Now that you understand the benefits of testing your email campaigns, let’s examine five things you can test in your emails right now to get better results:

1. Subject lines

Subject lines are probably the most commonly tested element of emails and at Campaign Monitor we make it wicked simple to test yours through our A/B Test feature.


Some interesting things you can test in your subject lines include:

  • Length – Test short subject lines vs. longer subject lines (this is the topic of much debate in the marketing world)
  • Topic – Test two completely different topics as the subject line, to see what content is of most interest to subscribers
  • Personalization – Add personalization to identical subject lines to see if a first name greeting, for example, gets a better response.
  • Promotion/Offer – See what kind of promotion works best by offering “Free Shipping” vs. “15% Off”

2. Pre-header

Do you use pre-header in your email campaigns? Pre-header text is the first line of text in your email and can serve as the wingman to your email subject line providing more context to your subscribers of what the email is about. This is helpful in the preview pane of email browsers. Often as marketers, we overlook the opportunity that pre-header presents to help improve or increase our open rate.

Some interesting things you can test in your pre-header test include:

  • Inclusion – Test including a pre-header and not including one and see if the version with the pre-header has a higher open rate.
  • Content – Include two different topics in your pre-header and see which your subscribers respond best to.

3. Day or time

One of the most common questions we get at Campaign Monitor is what’s the best time or day to send an email. And guess what? As marketers ourselves, we tell it like it is: It depends.

And that’s not a cop-out.

Because every business has a different list, a different level of engagement and, of course, different content, there isn’t a one size fits all answer.

Testing the day or time you send your email is an amazing opportunity to figure out what works best for your list by looking at the change in your open or CTRs.

If you always send your newsletter on Monday, try sending it on Tuesday at the same time and see what happens. Or, maybe you always send your newsletter at 9 am. What would happen if you bumped that up to 6 am?

4. Call to action

Are your calls to action getting the kind of action they deserve? When was the last time you tested yours?

Some interesting things you can test in your call-to-action tests include:

  • Copy – Test generic call-to-action copy like “Buy More” vs. more specific copy like “Get the Flare Jean Now.” In the past, we’ve done several A/B tests comparing benefit-focused copy to generic copy and each time the benefit-focused copy has increased click-through rates by about 10%.
  • Color –  Your call-to-action should complement the rest of your email, but still stand out. Test different contrasting colors to see which colors get the best response. Our friends at Unbounce declared orange to be their winner.

5. Content

We’ve all read a million times that content is king, but do you really know what content performs best in your emails?

Some interesting things you can test in your content include:

  • Length– Short form content or longer length content. Does your audience prefer short snippets with a link to read more on your site, or do they want to delve deep into longer copy?
  • Specific or Generic – At Campaign Monitor, our Dynamic Content feature enables you to display different content for different people, based on what you know about them. You can test dynamic content vs. generic content and see if you get a lift in click-throughs.
  • Positive or Negative language – You may be scratching your head when you read this one, but you can also test positivity vs. negativity in the language of your email. When you incorporate positivity into your email copy, you engage your reader’s brain in a much more powerful way, enabling them to easily understand your key messages and increasing their motivation to click-through and purchase your product. We ran a test using positive language and increased our email conversion rate by 22% using positive language so it’s definitely worth a test.

4 tips for conducting successful email A/B tests

Before you jump into the testing pool feet first, follow these four tips to set your test up for success:

1. Know what you’re testing and why you’re testing it

This tip is common sense, but, as marketers, we tend to get excited by something shiny and go running off in that direction without thinking things through. In the case of testing, make sure you slow down and figure out exactly what you want to test and what you hope to gain or learn by testing it (and how you’ll measure it).

Take your email subject line for an example—you may want to test both the length and the subject of it. Take it one piece of information at a time. If you want to test the length of the subject line, then you’ll want to focus on that before you know what information you want to include in the actual subject material.

What is the best length for your email subject line? This comes down to which devices your subscribers are using to open your emails. While thousands of email subscribers are still using desktop computers, email opens on mobile devices has drastically increased.

In 2018 alone, 61% of emails were opened on a mobile device.

With that in mind, there’s no way of knowing which devices your subscribers are using, so an ideal subject line character count should fall between 25 and 70 characters.

2. The rule of two

Now that you know what you want to test and why you need to stay focused. The golden rule of testing is only to test two variants at a time. For example, test two subject lines against each other to see which one performs better—as measured by the open rate—then you can use the top performer to send out a campaign to your list.

We recently did this by testing which call to action our readers preferred between a link and a button.

While some brands choose to use a link for their CTAs, our research has shown that using buttons for your call to action is actually more beneficial for your click-through rates. We tested two variations of our email, one with a link CTA and one with a button—the results were astounding.

tips for testing your emails

Source: Campaign Monitor

Once we added our green button CTA, we saw a 28% increase in click-throughs on this email.

3. Take action on your results

How many times have you run a test, only to do nothing with the results? Don’t let this happen to you. Have an action plan in place when you go into your test, and don’t wait until afterward to make it up.

For example, in the subject line test we suggested earlier, you would test two variations of your chosen subject line (length and subject) by choosing a small sample of your subscribers and sending half of that sample email A and the other half email B. Depending on which one performs the best, you’ll take that subject line and use it for the campaign that you send out to the rest of your subscribers.

4. Test again and again

Too often as marketers, we have a one-and-done mentality. When it comes to testing your emails, you need to have a test-and-test-again approach because many factors can influence your results, from time of year to the weather to the makeup of your email list.

Testing is an ongoing process. CoSchedule tested their email subject lines for three months to determine the best subject line for their Content Marketing Update email.

Wrap up

When it comes down to email marketing optimization, one of the absolute best ways to see what works and what doesn’t is through A/B testing. Testing one email against another is the only way to know what sits well with your readers, so start simple.

  • Run an A/B test. Don’t run just one, run a few. Start with testing out subject lines to see what users click to open, then run another test to see which content they prefer or what design sits well with them.
  • Collect the data. Make good use of your analytics to review your test results. The materials that garner more open and click-through rates are the pieces that are sitting well with your readers.
  • Use the data. Take your combined bits of data from your various tests and use them. Analyze the emails that performed well and combine their various aspects.

Still need more convincing? Check out our piece on A/B testing fundamentals and learn not only why this method is essential, but how to start doing it now.

Your turn: What A/B tests have been most successful for you? Share your success stories in the comments below!

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This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.
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