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If you’re not 100% satisfied with the results of your email marketing campaigns, you might think that it’s finally time for a change. But what do you change and how will you know if it worked?

The answer is as simple as the solution is powerful: split testing. This means sending two or more emails that are exactly the same except for one, small difference. Whatever you decide to change is what you’re testing.

It’s often reported that email marketing offers the best ROI of any channel. This claim can be somewhat misleading, though. That’s because email marketing involves a number of different variables. Achieving that impressive ROI is only possible after you optimize each of them.

Furthermore, while social media, videos, and blog posts all have fairly hard-and-fast rules for what makes them successful across industries and audiences, the same can’t be said for emails.

That’s why it’s so important for all email marketers to split test their email marketing campaigns before sending them out to your entire list.

7 email split testing ideas to implement right away

The more you split test–sometimes called A/B test–the better your email campaigns will become: The more you test, the more you learn, and the more you learn—and of course, the more you apply what you’ve learned—the more successful your email marketing campaigns will be. This means tapping into that massive ROI for yourself.

Not sure where to begin? Here are the 7 most common split tests you can run today.

1. Your subject line

If you take nothing else from this article, it should be that you absolutely must split test your subject lines.

As it’s the first thing your recipients will see, it should come as no surprise that your subject lines are essential to the success of your email marketing campaigns:

  • 69% of recipients will report messages as spam solely because of their subject lines.
  • 47% of recipients open messages based on their subject lines.
  • 22.2% of recipients are more likely to open personalized emails.

Obviously, an effective email subject line can make or break the success of your email marketing campaigns.  That said, every market is different.

Some audiences want longer, more descriptive subject lines. Others may actually appreciate something short and pithy.

This is why you have to split test your subject lines, again and again, to learn what works for your specific audience in your specific industry.

When crafting your next split test, try changing up these aspects of your subject line:

  • Word count
  • Topic Type
  • Statement vs. Question

Don’t forget that your subject lines can now include emojis, something else that’s worth testing. You may find adding a relevant emoji has no effect on your metrics, but, since so few marketers use them, it could also be an eye-catching feature that leads to more opens.

Here are great sources for emojis you can add to your subject lines:

Again, every market is different, but the average open rate across all of them is almost 25%. Keep split testing to see whether your subject lines are producing the same or, ideally, even better.

2. Email message length

How long do your emails tend to be?

Many marketers don’t have a set standard length for their email copy and simply write until they think they’ve covered everything their message requires.

However, the truth is that your market most likely has a preferred length for emails. Understanding what it is will improve engagement, responses, and even conversions. Falling outside of this preference will probably hurt all three and may mean recipients don’t bother reading the full message.

According to Boomerang’s research, the ideal length for an email is between 50 and 125 words. Emails that fell within these two lengths netted a response rate above 50%, proving just how important it is to pay attention to the length of your messages.

This email from Vimeo is short and to the point:

Vimeo email split testing ideasSource: Really Good Emails

Would similarly short copy work for you? Split testing can show you when to get to the point and when you should slow down and take your time explaining something.

As with subject lines, though, you can’t be sure if this average range pertains to your industry and target audience until you do split testing. Try keeping the same overall topic for your email and maintain the same type of formatting and calls to action (CTA), but change the number of words you write and see what happens to your metrics. Continue testing until you find the range that yields the best opens and engagement for your list.

3. The format of your message

One factor that will have a huge impact on how many words your email can be is how you decide to format it. For example, you may find that your audience reacts best to emails that are just 75 words.

However, if you use different fonts, text sizes, and headings to break up the copy, you might be able to push that to 100 words or more without sacrificing any engagement. In fact, switching up your formatting might even help with engagement.

There are countless ways you can format your email messages. You might choose to split it into two or three rows. You may decide to use more or less whitespace. The easiest way to change the formatting of your email is by using email templates or by perusing your own inbox for ideas.

4. Images and GIFs

Another way to potentially make your email copy more engaging is by including images and GIFs. When someone scans your email message, they’re bound to see them, which might compel the reader to pay closer attention to your copy.

Pizza Express uses images to great effect. Their subscribers probably got hungry just looking at these images:

Pizza Express 2 for 1 dealSource: Really Good Emails


While images and GIFs should definitely improve engagement, your targeted audience probably prefers a certain number of them, no more and no less. It’s a good idea to not only test including images and GIFs, but to also test how many images become too many.

The 30% rule states that you should dedicate that much of your email’s body to images, leaving the other 70% for the actual message. That’s probably a good place to start, but A/B testing the same copy and format with a different number of images is the only way to be sure what will work best for your specific email list.

5. Time and day the message is sent

No article about email split testing ideas would be complete without mentioning how important it is to look at when you actually send your messages.

Your recipients most likely have packed inboxes. Who doesn’t? On average, office workers receive 121 emails every single day. Many of your recipients won’t even see your email if it’s buried under 100 or more.

That’s why you need to split test until you figure out when your recipients are most likely to check for new emails. Otherwise, your open rate will suffer, as will engagement and click-throughs.

Generally speaking, the best days to send emails are:

  1. Tuesday
  2. Thursday
  3. Wednesday

The best times to send your emails are:

  1. 6 am
  2. 10 am
  3. 2 pm
  4. 8 pm

As with so many other facets of a successful email marketing campaign, though, you’ll have to test these to see which days and times tend to get the best responses from your audience.

6. Soft sell vs. hard sell

Here’s a really important feature of your email marketing campaign that far too many–probably most–marketers never think about: Does your audience prefer the soft or hard sell better?

A soft sell is an indirect approach to the sale. It usually involves some kind of relationship building, often through an entire email sequence that will feature numerous messages aimed at building trust with your subscribers. Along the way, the recipient may be encouraged to click through to a landing page where they can learn more about a product or service, but the actual “buy now” message is never overtly stated.

A hard sell is the complete opposite. It’s the kind of email message that ends with the “buy now” button and takes on the form of a more traditional sales email.

Nokia's mother day offerSource: Really Good Emails

Your audience may show more interest in one than the other. You may also find that different types of promotions decide which type of selling will produce the best results.

7. The number of CTAs you include (and what kind)

Speaking of conversions, no matter what the goal of your email is, you’ll usually need to convince the reader to click your CTA.

Conventional wisdom states that your email should always stick to one–and only one–topic, but some companies, especially publishers, need to promote multiple types of content and appeal to multiple types of readers.

Of course, conventional wisdom also says you should only have one CTA in your email. That may not necessarily lead to the best results, though. The oft-repeated advice probably stems from the only-one-topic maxim.

Publishers such as Refinery29 need to drive traffic to a lot of different posts. Though providing this many CTAs could easily become overwhelming and decrease their engagement, by using lots of whitespace and including short headlines, the email is easily digestible at a glance, even on a smartphone.

Refinery29 newsletter

In reality, many companies have increased their clickthrough rate by providing more than one CTA in the body of their message. This is especially helpful when the body of your email is longer. Consider split testing CTAs and CTA locations to learn what works for your list.

There are also multiple ways to include a CTA. The obvious example is a simple link, but you could also use a button. You could also use a button placed against a graphic.

Wrap up

Companies that achieve the envious ROIs email marketing is capable of only do so after running split tests over and over and over. Pick a specific goal for your next email campaign and then keep testing different features until you achieve it. Optimizing subject lines, for example, can help you achieve the highest possible percentage of opens while testing your CTAs will lead to increased web traffic.

Whatever you decide to choose as your goal, there’s a split test to help you achieve it. And once you do, the next step is simple: Pick another goal and get back to split testing. As digital marketers, we have to constantly evolve with the shifting trends in order to stay on top of our industry, but split testing makes that simple.

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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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