Modern marketers have caught on to the fact that email marketing is one of the most effective selling tools around. While engaging copy and value-adds are a big part of that, one of the core ways that emails convert is through the use of a call-to-action, or a CTA.

But it’s not enough to insert a “Click Here” button into your email and call it a day. The design of an email CTA matters. And it can have a major impact not just on whether readers click through a particular email but on the ROI of your email marketing efforts overall.

What is an email CTA?

For those not familiar, an email CTA is a button or linked text that directs readers to take an action resulting in further engagement with your brand. This could include downloading free materials, signing up for trials, purchasing products, reading a blog post or learning more about your brand’s products or services on a landing page. When done right, a great email CTA can play a major role in generating leads, guiding prospects through the sales funnel and boosting conversions.

How to design an email CTA

1. Use a button (and make sure it looks like a button)

CTAs can take the form of HTML-based buttons, image buttons or simple linked text. While your mileage may vary, HTML buttons are the best option most of the time. At this stage in email marketing history, people are programmed to identify buttons and know what to do with them. This helps explain why one case study found making CTAs look like buttons led to a 45 percent increase in click-through rates.

Additionally, HTML offers more control when it comes to determining how the button will appear on various devices, in different browsers and so on. And since some people disable images in their email, an image-based button may not show up at all. If you are using an image-based button, include alt text so readers still get a sense of the CTA.

In order for buttons to tap into our click-happy programming, they need to look like buttons. That means they should have a defined shape (typically rounded or rectangular), display a color that contrasts with the rest of the email, and include some copy. They should also look clickable. For example, a gray button is less likely to convert because people will think it’s disabled. In contrast, a colorful button with clear-cut text will make it obvious that clicking is the next step for the reader to take.

Some designers experiment with stronger directional cues such as shadowing, gradients, or arrow icons on the button. (One case study found that using arrows boosted their click rate by 26 percent.) Do some A/B testing to determine whether they’re worth your time. Just remember that clean and simple is better than cluttered and clashing.

2. Color carefully

If you’re here, then you no doubt have an interest in design—which means we probably don’t have to tell you that different colors can evoke different emotional responses.

Unfortunately, we can’t tell you that there’s “one best” color option for an email CTA. There are a ton of conflicting reports on this topic. For example, one case study found orange CTAs were best for boosting conversion rates. Another found that red was best. Yet another advocated for using green.

In order to determine the best color for your campaign, think about the emotions you’re attempting to evoke and the actions you’re hoping to inspire. But even more critical is emphasizing visual contrast. Whatever color you choose should stand out from the rest of the email (without clashing) and shouldn’t be reused elsewhere in the email. Make use of ample white space around the button to further ensure it’s visually prominent.

3. Locate thoughtfully

CTA positioning is another important but highly specific topic, which helps explain why there are so many conflicting opinions on the subject. The best location for your CTA will be determined by A/B testing, but here are a few considerations to guide your efforts:

  • Place the CTA on the right-hand side of text or images to take advantage of the natural directional flow of readers in the Western world.
  • Place the CTA “above the fold” to capture the attention of readers who won’t scroll to the bottom of your email.
  • If you anticipate that you’ll need to do a lot of convincing to get your readers to click, providing the explanation before the CTA and locating the CTA “below the fold” (after they’ve been convinced) may be helpful.
  • For the best of both worlds, consider repeating the CTA once early in the email and once later on. (But make sure only one of these is an actual button. More on this below.)
  • If your email is most likely to be read on mobile, consider placing the CTA in the upper-left corner in case the email app doesn’t properly autoscale. This will help ensure the CTA isn’t cut out of the frame.

4. Reduce friction around the CTA

No matter where you decide to place your email CTA, surround it with “click triggers,” or bits of information that help convince customers the CTA is worth pursuing. These could include a testimonial, star rating, compelling statistic, guarantees and so on. Help readers feel like clicking through the CTA will be time and effort well-spent. Just remember not to eat into the whitespace around the button with these elements.

5. Maintain consistency

CTAs typically lead people to dedicated landing pages, blog posts or other online content. So it’s helpful to think of the CTA that directs people to these destinations as part of the content they’ll find there.

With that in mind, maintain design consistency across the email, the call to action and the ultimate destination. Readers shouldn’t click the CTA and then worry they’ve ended up in the wrong place because the design is wildly different. Maintaining a cohesive design will help make the experience of interacting with your brand’s content as seamless as possible.

6. Don’t neglect the copy

When designing an effective email CTA button, good copy goes hand-in-hand with good design. The most compelling copy will tease the benefits someone will receive by clicking instead of merely telling them to do so. As an example, consider the difference between “Click Here” and “Get Your Discount.” The first is just an instruction, while the latter implies the person will receive something enticing if they click.

Also, make sure the action corresponds to where they are in the sales funnel. For example, you probably shouldn’t have a “Buy Now” button if this is the first email communication you’ve had with a prospect. Instead, it might be more appropriate to say “Tell Me More” or “Download Free Ebook.”

The point? Whenever you’re designing a CTA, it’s important to take the copy and its context into account.

7. Size appropriately

When sizing your button, aim to find the sweet spot between “not too big” and “not too small.” To that end, consider the following:

  • Button text should stand out. That means it should be noticeably larger than the email’s body text. A good rule of thumb is to use a font size of at least 16 px for CTA buttons, especially if your emails will be read on mobile (which they probably will be).
  • Bigger is not necessarily better. Your button should stand out, but it shouldn’t be aggressively large relative to the copy in the email. One case study found using a massive CTA button actually decreased clicks.
  • Mobile matters. Remember that mobile users will need buttons to be touch-friendly and large enough to be easily legible on a mobile device. Apple recommends a minimum of 44×44 pixels for any clickable design features.
  • It’s helpful to gain a different perspective. Eliminate some of the guesswork by using the (highly scientific) Squint Test: Look at your email design through squinted eyes. If you can still easily identify the call to action button (but it’s not dominating the entire page), odds are good you’re on the right track.

8. Don’t overdo it

Some emails can successfully pull off having more than one CTA. But for the most part, you’re better off limiting yourself to one clear and well-designed call-to-action.

If you give people too many options, it can overwhelm them and make them less likely to click on anything. This helps explain why one case study found reducing the number of CTAs in an email from four to one resulted in a whopping 42 percent increase in click-through rates. Another found having only one CTA in emails increased sales by 1,617 percent.

If you must include more than one CTA in an email, limit yourself to one button and make the rest of the CTAs hyperlinked text. Make the button correspond to your highest priority when it comes to readers’ actions.

Final takeaways on email CTAs

As you can see, there are very few hard-and-fast rules when it comes to designing an email CTA. Instead, there are several important factors to keep in mind, and (frustratingly) several conflicting opinions regarding the best way to approach each of those factors. That’s why it’s critical to commit to A/B testing your design efforts so you can learn about the colors, messaging, sizing and placement that is most likely to boost conversions with your brand’s specific audience. Through careful attention to design and thorough A/B testing, you’ll be well on your way to creating CTAs that convert.

Dan Scalco

This article was written by Dan Scalco, founder and marketing director at Digitalux, a digital-marketing agency, and regular contributor to Inc., Entrepreneur and the Huffington Post.