Email Marketing

6 strategies to improve subject lines and increase engagement

Marketers know that the subject line is one of the most critical components of their entire email. It is the first thing recipients see in their inbox and the primary determinant of whether they engage. In fact, 47% of email recipients say they open a marketing or promotional email based on the subject line alone and 69% say they will report an email as spam if the subject line is suspect.1

Below are some subject line tips that may help you increase open rates and keep audiences engaged:

1. Personalize your subject lines

Getting customers to open your email isn’t as easy as using their name in the subject line, but using their name helps. A Data Axle study found that personalized subject lines boost open rates by 50% and drive a 58% higher click-to-open rate (CTO) than non-personalized ones. Personalized subject lines may seem straightforward, but they rely on accurate data to be effective. A customized email subject line can feature various data points about the recipient: their name, location, birth date, a previously purchased item, a new product that is relevant to them, or their zodiac sign and much more.

Recommendation: Run A/B testing for personalized and non-personalized subject lines. Ensure your data is accurate, as an email with the wrong first name or location in the subject line will likely be ignored or become a cause of frustration.

Brand example: TakeLessons Live

TakeLessons Live is an online learning hub that offers a variety of classes – particularly language and music. Jessica Dais, a content marketer with TakeLessons Live says that their subject line “Hi [First Name], Quick question.” generates a 24% open rate, well above the industry average. Dais attributes the success of this subject line to its personalization and conversational tone. Dais also has another tip, “The use of the word ‘quick’ provides even more incentive to open it — because everyone is busy, especially when sifting through loads of new emails! Keep it simple and give the recipient a compelling reason to see what’s on the other side.”2

2. Track your best-performing subject lines

Data is the only way to know what subject lines will work best for your target audience. Taking a generic approach to your subject lines will only result in unsubscribes. For example, some segments of your audience might respond well to “last chance” or “exclusive” offers, and others may find it off-putting.

Recommendation: Track your open rates and subject lines from the past quarter; and identify the themes that produced the highest open rates. Next, go back and review your data from the entire last year to get a comprehensive view of your subscribers’ responses to see trends.

Service and solutions providers such as Data Axle can help companies simplify this process by collecting and analyzing campaign and audience data, then using it to develop comprehensive testing and content strategies.

3. Optimize for mobile

Campaign Monitor looked at the data from nearly 6 million email campaigns and found that 47% of all recipients across demographics use a mobile application to check their email, and only 26.9% prefer desktop over mobile.3

When it comes to writing a subject line, marketers need to keep in mind that mobile devices will show only 25-33 characters.

Recommendation: Segment your audience based on platform/device use and test different subject lines. Test variations of shorter and longer subject lines in each platform to identify the length that generates optimal engagement. Working with a solutions provider can help streamline this process. The Email Builder functionality of Data Axle’s Inboxable tool helps users see how their email renders in dozens of mobile, desktop, and web clients so they can adjust subject lines, pre-header text or any design elements to better cater to their audience. Brand examples: Silver Eagle and Old NavyBelow is an example of a 75-characters long subject line and how it renders in a mobile device. You’ll notice that while the full subject line conveys a lot of information in a desktop environment, its mobile equivalent is a lot less informative. If you were to view this email on your mobile device, you’d know this is a SALE promotion, but the context of a 4-hour, today-only sale would be lost.

Full subject line:
SILVER EAGLE FLASH SALE: Your early access for today’s 4-hour sale is here!

Here is a second example of a subject line with just 22 characters; despite its conciseness, it encourages engagement through a mystery offer and an emoji. Who doesn’t love a good deal?

4. Incorporate emojis

The use of emojis in subject lines isn’t new, but it is on the rise. Jess Nelson of Email Marketing Daily reported that “the use of emojis in mobile and email marketing messages has increased 775% year-over-year.”4 There are a few reasons for this. The biggest one being that subject lines with emojis generate a higher open rate than those without.5 To our point above, emojis work well on mobile, they help your email stand out in increasingly crowded inboxes, and they convey emotion without upping word count.

Recommendation: Keep your emoji relevant to your subject line; for example, use the bathing suit emoji to promote a swimwear sale. Don’t overload your subject line with emojis – one per subject line is generally a good rule of thumb. Try testing subject lines that utilize emojis and see which ones resonate with your audience. If your target audience is older, you may want to stay away from emojis that are too whimsical, like this popular one 💩.

Emojis can also be tricky to render. Once again, our tool, Inboxable, allows you to see how your subject lines and emails render in dozens of mobile environments, browsers, and web clients to enable you to course-correct if something’s off.

Brand example: Search Engine Journal

The Search Engine Journal, an online publication for SEO professionals, decided to test the use of emojis in their subject lines. While the emojis didn’t have a substantial impact on their open rates, the data did show that the users who responded to the emojis were more engaged – as they had a higher click-through rate, by 65%.6

5. Test Subject Lines on Non-Openers

If you have a compelling offer for your customers, an initial send to non-openers with a few subject line variations will help you identify the best-performing one to send to your audience and help optimize engagement. Why non-openers? There’s a chance your original subject line didn’t compel them to open the email, and a different one might change the result. Revise your subject line slightly with a few different approaches: you can use keywords such as “Reminder” or others that communicate urgency, “Final Hours” or “Last Chance,” or you can experiment with subject line personalization.

Recommendation: Run A/B subject line tests for non-openers and non-purchasers. Review the open rates, click-to-open rates, conversion/revenue, and unsubscribe rates to identify the subject line winner from a holistic perspective. Deploy the winner to your engaged segment to ensure optimal message performance.

Stay on top of your analytics to see which subject lines are keeping subscribers engaged. Image via Inboxable.

6. Put discounts into your holiday-themed emails

A recent Data Axle study found that holiday emails sent in Q4 often drive higher conversion rates than business-as-usual (BAU) emails, despite generating 16.8% lower open rates. The study found that including an offer like a dollar discount or percent off in email subject lines also drove a significant boost in conversions. For example, Black Friday emails with a free shipping offer in the subject line generated triple the conversion rate of BAU messages, making it the best-performing offer type for Black Friday. Similarly, New Year’s campaigns featuring a percent off discount in their subject lines drove a 40 percent higher conversion rate than BAU emails.7

Here are a few real-world examples:

  1. Toms: Your holiday style guide 🎄 | 35% off ends tonight
  2. Francesca’s: Last Chance To Get It Under The 🎄 for 50% off!
  3. Wine Insiders: 40% off to get ahead of the holiday rush
  4. JetBlue Vacations: The Black Friday Sale: Up to $400 off
  5. Yandy: ✨🍾Happy New Year! Extra 20% OFF Sale!🍾✨
  6. Whole Foods Market: 30% Off Shrimp & Caviar for New Year’s Small & Small

Recommendation: Be as specific as possible about the benefits of shopping with you in your holiday subject lines; emphasize the percentage or dollar amounts shoppers will save.

Brand example: Orly

LA-based nail polish brand, Orly, used the subject line, “Black Friday Starts NOW: 40% Off Site Wide.” The subject line conveys a sense of urgency, emphasizes the exact percentage off and communicated to the recipient that all their products are eligible for the discount in 42 characters.

Matt Hickman
Matt Hickman
SVP Sales

Matt Hickman services as the Senior Vice President of Sales at Data Axle. Matt has 20+ years’ experience as a sales leader and mentor, speaker, sales strategist, and digital marketing executive. He’s passionate about bringing innovative CRM technology solutions to complex marketing challenges and has deep expertise in new business development in SaaS and agency services organizations, with a focus on innovative prospecting, lead generation, and revenue growth with leading global brands. In his free time, you can catch Matt mountain biking or fly fishing in the pristine rivers of Oregon.