September 09, 2014
Case Study

Email Marketing: Cold testing subject line symbols leads to increased open rates for health care company

SUMMARY: When the marketing team at DaVita Kidney Care started taking notice of symbols popping up in the subject lines of their personal inboxes, they began questioning whether or not these symbols could be implemented in their own email program.

Read on to find out how the team set out to integrate this new and off-beat tactic into their testing and how they discovered for themselves whether or not this strategy provided any results from their consumers.
by Courtney Eckerle, Manager of Editorial Content


A Fortune 500 health care company, DaVita Kidney Care operates kidney dialysis facilities across the country and around the world.

"We take pride in providing information to treat all stages of kidney disease, including risk education, maintaining a healthy lifestyle and support for patients currently on dialysis," said Mike Larkin, Email Marketing Lead, B2C, DaVita Kidney Care.

He added that the company leverages the email channel to maintain relationships with customers by sending messages that reflect the company's mission of education and support. Outreach is meant to be "both a proactive and reactive message management."

A lot of this outreach is behavioral-based, he said, tracking actions from email sends to the DaVita website. Alongside that, a staple of the team's email strategy is testing, which has been "solidly embraced."

He has seen this shift during his time at DaVita, where across the board "everybody wants to test everything," he said.

Larkin added, "I'm very lucky, in this position, to be allowed to go nuts with testing. I haven't had that to this extent in any other position I've worked in … it's interesting to have this kind of dedication to rigorous testing. It's great, and it pays dividends."


It was this attitude and testing culture that allowed Larkin and his team to implement a quirky idea they stumbled across.

"A little over 18 months ago, we noticed a surge in email marketers using quirky symbols in their subject lines. Retailers were matching up small pictures that displayed in their subject lines with the actual offers," he said.

Larkin and his team realized that many marketers had rediscovered an extension of email coding protocol called MIME (multipurpose Internet mail extensions) that can hardcode simple small symbols into the subject line, "making them almost bulletproof across platforms," he explained.

The team would drop code into their subject lines. For example, this code would show up as a star symbol:

As most of DaVita's messaging is kidney, diet or lifestyle-related, "our subject line options tend to sound similar in tone. Being in health care, we are limited in our ability to boost interest in our information," he said.

Larkin and his team realized that this could be a way to stand out in a virtual world of crowded inboxes.

"As a B2C email marketer, I found the practice intriguing, but I couldn't find any info about it at the time. Beyond knowing open rates, I wanted to know if these symbols were interfering with delivery rates or increasing abuse complaints or unsubscribes," Larkin said.

The team's goal was to create and analyze data on the use of subject line symbols within their own campaign and see if these symbols had any impact — positive or negative — on metrics.

Step #1. Develop a vigorous testing process

"I've got a series of about 10 questions that I ask myself about subject lines every time they go out," Larkin said. "You can't test for all of those variables every time, but you can test for a couple of them."

DaVita uses a platform that allows the team to perform A/B testing with four variables, so they can experiment with minor tweaks in each send.

"I test every mailing I send out, because I can. There's no reason not to. I'm basically leaving stronger open rates on the table if I'm not testing," Larkin said, adding that he has two best practices he will insert into the testing process with two variables.

In an effort to continuously improve the email program, the team set up a rigorous A/B testing process to streamline language and length in subject lines.

"We were nudging the engagement needle up with every test — our team performs more than 50 A/B tests annually to ensure we are maximizing our open rates," he said.

They try to be on the edge of digital marketing techniques, he added, and testing is how they allow room for new ideas that show promise and viability.

"When we saw other marketers using subject line symbols, we had our analysts begin researching what kind of impact marketers were gaining by including these in emails. There was nothing to find at the time. It was too new of a phenomenon to have any usable results," he said.

Larkin decided to chase after the idea anyway and discover the merits for himself.

Step #2. Get team buy-in

"When I approached my team with a proposal to test symbols in subject lines, there was a hesitation about incorporating something that could be construed as 'frivolous,' something that could possibly detract from our messaging," Larkin said.

With no outside results to look at, Larkin and his team were going to have to start testing cold.

The process of getting everything up and running wasn't an easy sell, he added. With no research to rely on, the only results the team was able to find were anecdotal.

"We discussed it," he said. "A lot of the stuff out there at the time was a little bit too quirky for us. It was … some little symbol of fireworks or a star or something. So there was hesitation on my team's part, justifiably, to start to get into this."

In the health care industry, Larkin added, companies have to take care to be taken seriously, and "[it's] not something that you put kitty cats into your subject line just to boost an open rate."

Larkin and his team were concerned about subject line symbols having an effect on the delivery rate, and to assuage all concerns, they put together a plan for "a smaller scale than we're used to doing, so we could prove it out one email at a time," he said.

Step #3. Test early and on a smaller scale

The team set up an internal test first in a survey invite before rolling out the campaign to the consumer mailing list.

"It was a low-risk gamble with those guys … But the open rate was through the roof, and we could see right away that there was enough promise that we should start slowly testing. That's when we started rolling it out to patients, to upstream customers," he said.

Testing it out internally first allowed the team to get hard metrics as well as anecdotal evidence. The team decided to use a small black triangle, something simple that wouldn't be silly or frivolous, while still drawing eyes to the email.

"It looks like a carat pointing at the subject line. It just breaks up the inbox," Larkin said.

Creating the multipurpose Internet mail extension, or the black triangle, was "blissfully easy," he added. Larkin was able to build it himself using an external free website that creates the line code.

"If I had to bring IT into this, we'd be talking about this 18 months from now," he said.

The team created an A/B test to send up to four different subject lines simultaneously to a sample of the total list and then send the remainder the winning line.

This allowed the team to create a series of different tests and allowed them to observe several things:
  • Do symbols flag spam filters?

  • Do symbols raise abuse complaints in the contact list?

  • Is there or is there not a noticeable difference between symbol inclusion?

  • Is there is a difference in open rates depending on the kind of symbol used?

  • Is there is a difference in open rates based on where the symbol is placed?

The first two questions needed to be answered immediately, Larkin said. Starting with very small, but still statistically meaningful groups, the team began dropping the code into subject lines and monitoring deliverability, inbox placement and unsubscribes as well as abuse complaints.

Though none of those metrics showed any movement, according to Larkin, they were seeing slightly elevated open rates.

"We went through the exercise several more times until we were convinced that we would not take a deliverability or reputation hit by including these, and we then proceeded into the remaining questions," he said.

Step #4. Continuously test for viability

"It's an ongoing process. It's never-ending," Larkin said, adding "we're implementing what worked last week, hoping that it works this week, but putting in contingency plans in case it doesn't work."

Larkin and his team tested "a huge amount of symbols. Our DaVita logo is a dancing star, so there were some pretty rudimentary stars that we could use," he said, also listing arrows, checkboxes and flags as alternate symbols DaVita could use.

"We tried them all. We just didn't see enough of a difference to justify using anything quirky, so we stuck with the geometric shapes," he said, adding that they have never seen a significant statistical difference between symbols.

Close to Valentine's Day, he said, the team did their quirkiest symbol yet — a heart.

Larkin said that one interesting issue that arose had to do with iOS, Apple's mobile operating system, which "does all sorts of weird things with symbols … make note that if you're using symbols, you need to test across platforms."

However, in this case, the change proved to be a happy surprise. The heart turned red when a recipient was looking at the subject line in their inbox. However, it was out of their control and only discovered through testing.

"I thought there might be a little pushback from that. You know, that was about as quirky as we could get … but I didn't hear any negative feedback," he said.

Larkin and his team include a symbol in every email they send out, but always with a control group of non-symbols to ensure they are still providing that lift.

"That was what we were initially testing for, just to make sure that we weren't hurting ourselves or hurting our program. Like I said, we have such a strong deliverability rate. I can't afford to put that at risk," Larkin said.

"I saw nothing. I can pretty confidently say that, right now, emails are not flagged as spam with symbols in the subject line," he said.

"Sometimes something that worked yesterday doesn't work today," Larkin added. "So I'm going back and retesting. Seeing, OK, this is what I thought I should do in July. Does that hold true in August?"


"Subject line symbols were an interesting anomaly in this whole thing. They were standing out. They were a little quirky," Larkin said.

It was a hard sell at first, he added, telling his team "Yeah, it's new; it's different; it's weird, but let's take a chance; let's go for it. And this time, it paid off."

The results the team was able to produce revealed a consistent 1.5% lift in open rates when a symbol was placed at the beginning of a subject line.

The other takeaways the team was able to learn from this process were:
  • There was no hit to the reputation of the company or inbox placement

  • Sends were not flagged as "junk" by any major email provider

  • There was no noticeable movement in unsubscribes or abuse rates

  • The actual symbol doesn't matter as long as it is recognizable as a non-alphanumeric object — for instance, copyright and trademarks did not help open rates

  • Symbols at the end of subject lines proved ineffective

The advice Larkin would give to other marketers considering testing something similar to subject line symbols is, "Start testing. Start small. Show results up the chain. And, if you're getting results, you've got firm ground to stand on."

Creative Sample

  1. DaVita email


DaVita Kidney Care

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