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What makes a subject line work? Episode 2- Language Sophistication

Email subject line performance can be impacted by many, many things.


It’s what makes writing the perfect subject line for an email marketing campaign such an amazingly complex challenge.

Here at Phrasee, we love complex challenges.

We know for a fact that the quality of a campaign’s email subject line is the single biggest determining factor of that campaign’s success or failure. How do we know? We’ve done the research. So much research, in fact, that we’ve been able to break subject line language down to a science.

This subject line science has helped us quantify exactly what separates the email subject line wheat from the email subject line chaff, and exactly what kinds of subject lines make brands the most money.

Over our years working extensively with email subject lines, and AI-assisted in-depth performance data analysis, we’ve found that there are a few key factors in how an email subject line is constructed that directly impact that subject line’s performance.

They are:

    • Sentiment
    • Length
    • Phreshness
    • Word choice
    • Language sophistication
    • Scansion (Our CCO’s favourite)

We’ve decided to share what we’ve learned about these key subject line elements with our email marketing compatriots over 4 blog posts.

This week, wee tackle Language Sophistication…

6 things affecting subject line performance

What is Language Sophistication?

Dictionary.com defines sophistication as: complexity, as in design or organization.

The way that a sentence is structured – and the individual words used within that sentence – combine to make up the level of language sophistication in that sentence.

Using longer, more obscure words within a message can increase the sophistication of its language, but there are also more subtle ways to accomplish the same thing: reorganising the order of the message’s words, cutting out/adding words, including references, etc.

Language sophistication is, at its root, a measure of how the makeup and structure of a linguistic message affect how it is interpreted by the person or persons receiving that linguistic message.

And, when it comes to email subject lines, how your message is received by your audience can make all the difference in the world.

Why does it matter?

Like sentiment, the language sophistication of an email subject line can have a direct (and quantifiable) impact on how a brand’s audience will behave after reading it.

In a perfect world, we could simply tell you exactly how sophisticated your subject line language should be for every campaign, and your brand could simply implement it and watch email marketing ROI skyrocket.

Sadly, like so many things, subject line science just isn’t that simple.

Every audience is different. Every campaign is different (at least it should be!). Thus, how every audience will respond to different levels of subject line language sophistication in each campaign will be different as well.

Learning and understanding what level of language sophistication engages your audience most effectively can be extremely helpful in determining the level of language sophistication your brand should use when writing email subject lines.

Where does this learning and understanding come from?

Why testing, of course!

How can brands put this information to use?

Identifying what level of language sophistication engages an audience most effectively is an excellent first step toward better email subject line performance. Split-testing different language sophistication levels on your audience regularly – with a solid plan in place to learn from the results of your tests – will give you a good indication what kind of language sophistication is most likely to work for your brand on any given send.

Always keep in mind that the sophistication of the language your brand uses is a key aspect of your brand’s unique tone of voice. Maintaining consistency in your language sophistication is key, and matters just as much in your email subject lines as it does anywhere. Every touchpoint is a branded moment, and protecting consumer perceptions of your brand should always take precedence.

Luckily, with enough testing data to draw from, striking the right balance between high performing subject line language sophistication and your unique brand voice is entirely possible – as long as you are willing to invest the time and effort necessary to find the right balance for your brand.

Remember: how an audience responds to the language sophistication in your brand’s subject lines will shift over time, so it is essential to make regular split testing an integral part of your email marketing strategy.

If you keep testing, and keep language sophistication front of mind when building your brand’s email subject lines, you’ll soon see your email marketing ROI grow.

Better still, Phrasee’s AI language generation and split testing technology can do this all for you, simplify the process, and help your brand make more money sooner, rather than later.  Book a demo to find out how!

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