Data-Driven Innovation in Email

[Previously posted on eROI website]

Heidi Olsen
6 min readJan 19, 2022

As an agency working with large consumer-facing brands, eROI is often pushing the creative envelope in our campaigns. To support creative innovation in the inbox we rely on data to make smart choices that help us reach our goals to deliver a message to all subscribers.

Internally and for our partners, we use Google Analytics and Litmus Analytics to track, measure and report on our email campaigns. The data we are able to obtain from both systems provide us with insight on subscriber demographics, the devices they use, the time of engagement and the locations on the email they were most likely to click.



Identifying the breakdown of email clients your subscribers are on will help inform your email strategy. The opens tracked by the Email Market Client Share are useful to identifying the top 10 email clients used worldwide, but if the majority of your subscribers open their email in clients that run on MSWord, you may want to avoid using a mobile-first approach and focus on creating a stable experience on desktop.

Shovi Websites found that a traditional approach made more sense for their subscriber base due to the majority of subscribers opening their email in Outlook. In addition, the landing page and registration page the email was clicking through to was not optimized for mobile. Creating a cohesive experience for the largest portion of their subscriber list made the most sense.

However if your subscribers are opening your email on iPhone, iPad, Outlook 2011 and other clients that use the WebKit rendering engine, then you can look into creating more innovative emails.


Time of engagement in the email is useful to understand whether more interactive experiences are as successful as shorter, succinct messaging. Email marketers work to avoid long emails by focusing on above the fold in fears that asking the subscriber to scroll will decrease CTR. Without looking at your engagement data, you can never be certain.

Litmus Analytics will provide a breakdown of how long your subscribers engage with your email:

  • Read (8 seconds+)
  • Skim read (2–8 seconds
  • Glance/deleted (<2 seconds)

This information paired with device can help you identify key areas for optimization.


Google Analytics will help identify where subscribers click on your email by appending tracking strings to your links. It can also track the online behaviors of your most valuable email users, allowing you to run segment lookup and analysis, understand journeys, conversions and other reports that will help you make data-informed decisions in your email strategy.

This might include identifying whether a hero image is more engaged with versus a CTA (call-to-action) button. You can even create sophisticated A/B tests to pinpoint which of your email strategies are the most effective in terms of encouraging opens or clicks.


The following are examples of emails that the eROI team have created over the past 6 months. Since the interactions are dependent on time and device, feel free to open the email in browser to see the full experience.

CSS Animations

For our partner Taco Bell, we identified that the majority of their subscribers used email clients that ran on the WebKit rendering engine. This provided us with an opportunity to leverage CSS properties that are commonly not supported in email, including CSS animations.

The strategy for Taco Bell’s invitation to the world of Explore, their loyalty program, was to captivate an audience that thrives on early adoption and limited information to latch onto new adventures.

The success of the adoption of the app relied on social sharing. Historically we could achieve this with a “Share on Twitter” call to action, but we wanted to do something a little different.

We used CSS animations to fade out the headline and fade in the Explore campaign hashtag. An animated GIF would have also worked but is not as accessible as webtext. In addition it would have a heavy image load time. This hashtag reveal played with messaging to capture the sense of the wonder we wanted to attain with this welcome email.

With any use of innovation, it is smart to have a graceful fallback in order to not alienate other subscribers. In clients that do not support CSS animations, the text remains solid.

CSS Slideshow

Another example of leveraging CSS animations is a CSS slideshow. This also has a graceful fallback where each slide stacks in clients without support, ensuring that no subscriber misses the campaign messaging.

Our internal team at eROI created a slideshow for our welcome email series. To appear more conversational, the slides cycle through a few questions to ask the user to engage with our content. We even segmented our list to subscribers who engaged with our profile center and those who did not to help acquire more data and provide more personalized experiences for those users. The example below shows this experience.

Read this tutorial for full details on how to create this experience.

Scrolling Experience

For Taco Bell we looked at the time of engagement in their campaign emails. Surprisingly we were able to determine that the majority of their mobile subscribers were more engaged than their desktop counterparts, an average of 20 seconds on the email, providing us with the opportunity to create a rich experience for these subscribers.

eROI was tasked to create a campaign that celebrated Taco Bell’s 10 $1 breakfast items. We created vertical vignettes of three characters’ days centered around their breakfast decisions. The first character chooses Taco Bell (the right choice), the second no breakfast, and the last a competitor breakfast. The scrolling story depicts these three journeys simultaneously, providing the characters with surprising interactions throughout the day.

To make this work we leveraged the z-index CSS property and absolute/fixed positioning to mimic the characters weaving in and out of the illustration. Since those three properties only work seamlessly on iPhone’s native email client, we targeted the experience to only appear on that email client, suppressing the experience for other clients. The alternate experience displayed a CTA that encourages the user to view in browser.

Visit our Art Director Tatiana Mac’s blog post on the creative process for arriving at this concept.

Animated GIFs

Even with the right metrics, not all interactive experiences work the way you intended in the clients that support the technologies.

For example, we created a text conversation between the revived Beefy Crunch and Cheesy Double Beef burritos and Taco Bell Fans. Originally we wanted to use CSS animations to display each text message, but after testing in several live clients, we realized that the image load time got in the way of the cadence of the text messages. While it appeared to work perfectly in browser, it had uncontrollable delays on mobile, especially if that subscriber was on data vs wifi.


The following are examples of emails created by other agencies. Since the interactions are dependent on time and device, feel free to open the email in browser to see the full experience.

Punch Card Coding

This Bobbi Brown email by RebelMail uses what Mark Robbins coined as Punch Card Coding where you use a large array of radio buttons to create a functional email. Essentially you style the CSS based on the :checked values of those buttons. The support is pretty great, with the fallback linking directly to the product page:


SVGs are not 100% supported in email, but do have fallbacks that will ensure that an image is displayed in clients that have image enabled. StyleCampaign created an SVG Timer for email that you can read about here.


Anyone that identifies themselves as an #emailgeek will know about Litmus’ “Golden Ticket” challenge in their 2016 Email Design Conference announcement email. Litmus hid Golden Tickets within their email by using hidden hover states, backgrounds and comments. Upon discovery, the subscriber is asked to take a screenshot and Tweet with #LitmusLive. Not only was the engagement through the roof, but they had a social sharing component that took the conversation cross-channel.


When deciding how to innovate your email campaign, it is important to understand your subscribers and make sure that any use of experimental technology enhances your goal, and does not stands in the way.


Tweet at @swisswebmiss and hashtag #emailgeeks to share your innovative emails.



Heidi Olsen

Senior Developer by day, Fun Professional by night