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What makes a subject line work? Episode 1 – Sentiment

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

Things that make a subject line work: Episode 1 - Sentiment

It’s one of the aspects of the email business that makes it so darned interesting, and it’s the one aspect we here at Phrasee have been fixated on for years now.

We’ve said many times that the quality of a campaign’s email subject lines is the single biggest determining factor of that campaign’s success or failure. It’s true. We’ve done the research.

The big question is, what exactly determines “quality” when it comes to an email subject line? What separates the email subject line haves from the email subject line have-nots?

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 which 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, we begin with sentiment

What makes a subject line work? Episode 1 – Sentiment



What is sentiment?

The Oxford English dictionary defines sentiment as: “A view or opinion that is held or expressed. A feeling or emotion.”

The sentiment of any message refers to how that message will be interpreted, and what feelings this interpretation will arouse in the person receiving that message.

When talking about sentiment in written language, it is essential to bear in mind that the sentiment intended by the writer is not always necessarily the sentiment received by the reader. With vocal inflection and body language out of the picture, conveying sentiment becomes much more complex in written form. Anyone who has ever sent a sarcastic text message and had to explain that they were in fact being sarcastic after the fact will be all too aware of this fact.

Put simply, “sentiment” refers to the feeling(s) a message arouses, and what underlying signals that message conveys.


Why does it matter?

The interpretation and feeling aroused in an email subject line’s reader has a major impact on how that reader behaves after reading it.

While the sentiment of an email subject line can impact many key email marketing performance metrics,it can be most effectively measured by looking at email opens.

In our extensive research, we at Phrasee have identified 5 key sentiments which can be directly correlated with a subscriber’s likelihood of opening an email after reading a subject line.

They are:

  • Curiosity
  • Directness
  • Friendliness
  • Urgency
  • Off-beat

Every brand’s audience and subscribers will respond to the sentiments listed above in different ways, and larning/understanding which sentiments engage your audience the most effectively can be extremely helpful in determining which sentiments your brand should focus on when writing email subject lines.

How can brands put this information to use?

Identifying to what degree a particular sentiment is present in a particular email subject line can be a tricky business. Luckily, we at Phrasee have developed a free tool to help you measure the sentiment of any subject line. Simply plug in your subject line, and let the tool do the rest.

Identifying which sentiments engage an audience the most effectively is an excellent first step toward better email subject line performance. Testing different sentiments on your audience periodically can give you a good indication which ones are most likely to work for your brand on any given send.

Remember: how an audience responds to particular sentiments will shift over time, so it is essential to make regular testing a part of your email marketing strategy.

You may already experienced the perplexing phenomenon of a subject line which works well for a time, only to watch the performance of similar subject lines drop off shortly thereafter. At Phrasee we refer to this as “audience fatigue”. If an audience is exposed to the same sentiment too frequently, they will begin to disengage, and subject line performance will suffer.

If you keep testing, and keep sentiment 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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