I’m in the subject line business. So, it makes sense that my company keeps track of subject lines that brands around the world are sending.

We’ve built up one of the worlds’ largest databases of subject lines sent by B2C brands. It is all content that we receive in our inboxes after signing up on retailers’ websites, so it’s all public domain (no confidences are being broken, don’t worry!)

We took 32,198 randomly-selected subject lines from major global retailers and ran them through Phrasee Pheelings, a sentiment analysis engine we built specifically to quantify the semantic makeup of subject lines.

Note: In this analysis, we decided to not look at individual word frequency, as from a linguistic standpoint this is suboptimal. Why is this?

Take these two subject lines:

  1. Our new products suck big time and only idiots buy them.
  2. Our brand new products suck big time and only idiots buy them.

If you only look at individual words, some people would tell you that the second subject line is better than the first, because “brand new” is a better phrase than “new.”

But – the entirety of the subject line sucks big time and only an idiot would use either. So knowing that one word is better than another really doesn’t help you, as it doesn’t consider context or sentiment.

(Editor’s note: the author’s own example subject lines were ‘sanitised’ significantly here…).

Also, I’ve already done that sort of research a bunch of times, and a bunch of other companies have followed my lead. So, I’m kind bored of it. While perhaps piquing intellectual curiosity, it only tells you part of the story.

So instead, we looked at the overarching sentiment – that is, how humans actually interpret the language in full, not just word-by-word – and compared subject lines from 2,598 retailers across the UK, USA, Canada, and Australia, from January through March.

Spoiler alert: Most retailers use very similar language in their subject lines

A quick word on the methodology:

Phrasee Pheelings scores each subject line on five key semantic categories: urgency, friendliness, offbeatness, directness and curiosity.

These were derived from a factor analysis of over 20 emotions, which statistically converge on these five categories.

Why not measure more, say 15 or 17 or 19? Well, take ‘Urgency’ and ‘Fear of Missing Out’, for example. They have huge semantic – and statistical – crossover, so ranking both makes no sense.

The same goes for many other emotions. Measuring more doesn’t add statistical or semantic value, it just adds confusion and complicated charts that mean nothing.

We then took all the quantified semantic results and ran a variety of statistical methods to understand the nature of the data. One of these methods included a K-Means Cluster Analysis, which is how you find common subsets within a dataset.

We then used this cluster analysis to find similarities and differences that exist within the data.

The most common types of retailer subject lines are:

What are the individual clusters?

Cluster 1 – Very direct, very urgent.


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Very direct, very urgent. It’s a generic message, and could be for any brand out there, so it doesn’t build your brand at all. Helps with short-term sales lifts, but in long run trains customers to only purchase when a sale is on.

Cluster 2: Very direct, less urgent.


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Very direct, less urgent, and once again devoid of brand voice. Likely delivers less of a short-term sales uplift, but may get customers who are already in “buying mode” to move on their impulse.

Cluster 3: Descriptive, but ‘blah’.


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Descriptive, and devoid of humanness. Will interest some a bit of the time, but mostly not. When repeated, turns into one big, repetitive blah.

Cluster 4: Evokes interest.


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Evokes interest in what’s coming. For specific product ranges, will generate interest.

Cluster 5: Ambiguous, but benefit-driven.


Clothes worth making a *lot* of noise about

Ambiguous, but benefit-driven. When offering a wide product set, will enter people into information-seeking phase of buying process.

Cluster 6: Benefit-led and human.


Dry your laundry whatever the weather!

Pure benefit-led, and human-sounding. If you are facing a specific problem, this will solve it. Perfect for interest generation.

63% of retailer subject lines are generic, and they’re losing brand value – and sales – as a result

The vast majority of the subject lines in the data set are very direct, quite urgent, sound very similar… and could be sent from pretty much any brand.

That is fine if your brand’s voice is generic – but it’s not. (If your brand’s voice is generic, stop reading here).

Why are most subject lines so generic? There are numerous reasons:


Many email marketers benchmark their subject lines on what their competitors are doing. They’ll see something and go, “Oh I like that!” and write something similar.

But then, the market converges upon a mean of boring, samey-samey sounding subject lines. And consumers switch off, because there’s no linguistic differentiation between competitive actors in the marketplace. So subject lines just become one big blah.


If you’re an email marketer you’ll know what I’m talking about here; writing a subject line that strays from the status quo is difficult – for both political and fear-aversion reasons.

Political because often the subject lines need to get signed off by other people who are risk-averse; and fear-aversion because what if your subject line sucks? So people just do what they’ve always done, thus perpetuating the status quo.


Quite often, the writing of the subject line is left till the last minute. And in the panic to get the email out, there isn’t enough thought put into what it should be.

This results in a lack of creativity, and the perpetuating of boring, samey-samey sounding language. This is surprisingly common, as this study indicates.


People simply don’t like writing subject lines. Many email marketers spend more time on the data, or making the inside of the email look beautiful, or whatever else.

Both of these things matter – a lot – but if no one opens your email in the first place, then it’s all a waste of time.


If you’ve been writing subject lines for your brand for a while, then you’ll know how hard it is to keep coming up with new ways to ostensibly say the same thing.

And even the most creative copywriters in the world have off days. So if your email goes out today, and you’re having a particularly uncreative day, the easiest solution is just to settle on something boring.

If you don’t care about your brand, then use subject lines like these:

Here’s a couple subject lines that were mentioned on Twitter (not by us!) as being mega spammy:

Ouch. When your subject lines are being publicly shamed, that’s bad times, amirite?

Whoever is signing off these Argos lines, can I humbly suggest you consider an alternative linguistic pattern? You may be getting a few more sales in the short run, but in the long run it’s just going to alienate your customer base.

Interesting stuff! But hey, what does this analysis mean for me?

Your subject line is critical from two standpoints:

1) increasing short-run response rates; and 2) improving long-run brand perception.

The above data indicates that most email marketers focus on #1, in a fleeting manner, and ignore #2.

See, if you always send out repetitive “50% off deals unlocked – BUY NOW PLEASE” emails over and over and over, in the short term you’ll get a few more sales. But in the long term, you’ll train your audience to perceive your brand as a perpetual discounter. This means that they’ll learn to only buy from you when there’s a big sale on.

Or if you mis-sell, and say things like “You’ve unlocked a deal,” or whatever, like in the twitter examples above, when no deals have been unlocked, it will be detrimental to your brand.

This isn’t a good thing. So don’t do it.

The key to continued, on-brand success is to continuously and progressively explore the semantic variant space that exists within subject line language. There’s no such thing as boring brands – but there is such a thing as a boring subject line.

Stop copying. Stop being boring. Stop following the status quo. Your customers will thank you with their wallets.

You can get your own subject line’s sentiment ranked by Phrasee Pheelings for free here (Editor’s note: registration required).