What determines a good email? Let’s face it, we decide whether or not to open an email the same way we decide whether or not to open a book, by the cover. And that’s why the key to great email starts with the subject line. After the sender name, subject lines are your first point of contact with a customer. It’s where your company can offer value, pique interest, and invite engagement. So, what makes a good subject line? That’s the question our friends at 8tracks.com tackled earlier this year.

8tracks case study: background and challenge

“Sendwithus email analytics made it really easy to A/B test different subject lines. Over time, we were able to optimize the copy of our subject lines to render the highest open rates. ”

– Andrea Slobodien, 8tracks Marketing

8tracks is handcrafted internet radio. It offers a simple way for people to share and discover music through short online playlists. When 8tracks was working on a drip campaign to re-engage new signups, they decided to target users who had made an account, but who hadn’t returned to the service in two weeks. To do this, they sent out a little surprise. They emailed their users the hottest playlist on 8tracks to give them a sample of some great music. Using analytics and a/b tests, they pinpointed the subject lines that worked, and, as a result, they got higher open and click rates on their playlist and successfully re-engaged new signups. Today, 8tracks has 8 million monthly active users. So, how do they write their subject lines?

 The science of subject line writing

From Daniel Pink’s To Sell is Human, we learn that three researchers from Carnegie Mellon University found that people were more likely to open subject lines that fell into one of two categories: utility or curiosity. Emails either show their usefulness to the recipient, or they make the recipient curious about what’s inside. Emails that offered a utility or purpose were opened because they stated a clear gain or loss, and emails that appealed to curiosity were opened simply because they piqued interest. The researchers also found that utility emails worked better when users had lots of email to deal with (during the week or on a desktop client), but curiosity drove more attention under “conditions of lower demand” (during the weekend or on a mobile client).

 Pink adds a third rule behind great subject lines: specificity. He found that “mushy subject lines like “Improve your golf swing” were opened much less often than one offering “4 tips to improve your golf swing this afternoon”. Creating super-specific subject lines makes your utility emails more useful and more likely to be opened.

 Using analytics to focus your subject lines

Emails continue to outperform nearly all other marketing channels because marketers are able to pivot the messaging based on analytics. Using data like who actually read the email and what platform they were using, 8tracks found that most of the opens and clicks were from mobile users. After discovering this, they not only optimized their HTML templates for mobile, but they started a/b testing subject lines that piqued interest. Knowing that the majority of recipients were viewing their emails under “conditions of lower demand”, 8tracks pivoted their subject lines to appeal to curiosity.

 After testing the following subject lines:

–       We’ve missed you

–       We’ve got something for you

–       So, you’ve made an 8tracks account, now what?

–       Hot off the tape deck

8tracks found that ‘We’ve got something for you’ drove the most opens and the most clicks. By understanding the motives behind email opens, 8tracks was able to use their analytical data and leverage curiosity as a driver for more engagement.

 Below are the results of that a/b test:

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Subject line optimization is an on-going process, but it’s just the beginning. Emails offer one of the most reliable forms of engagement with your customer. Powerful email analytics will give you the data to navigate the tricky business of email branding, messaging, and call-to-action. For more tips on email a/b testing, analytics and messaging, visit us at www.dyspatch.io/sendwithus.