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5 signs bad subject lines are hobbling your email marketing campaigns

In email marketing, good subject lines are important.


In fact, in our humble opinion over here at Phrasee, they might just be the single most important element of any email marketing campaign.

For those who have been in the email marketing game a while, that might seem obvious. But we still think it’s worth remembering.

Long gone are the days when email subject lines were an afterthought when creating a campaign. Today’s email marketer is far too sophisticated for that.


In today’s email marketing landscape, every aspect of every campaign needs to be on point. Everything is tested, optimised, and tested again.

Or at least it should be.

The question is: Are your subject lines pulling their weight?   

Here are 5 signs they might not be…

5 signs bad subject lines are hobbling your email marketing campaigns


1) Low open rates


The subject line is the first element of your email marketing message that your audience sees, and it is your brand’s best chance to overcome the first barrier to email marketing success: subscriber indifference.

If your open rates are low, then your subject lines aren’t doing their job. Full stop.

The good news is there are plenty of ways to boost your subject line copy. Using Phrasee to generate AI optimised subject lines is a good start, but there are a number of other subtle tips, tricks and tweaks to try out.

For example, prioritising underlying sentiments over individual words, and of course split testing, can help any brand along the path to subject line perfection.

2) Plummeting click through rates

Many factors contribute to your email marketing campaign’s click through rates (CTR) and – surprise! – subject lines are one of them. Subject lines that are consistently clear, on brand, and in line with an email’s content are more likely to make subscribers click through.

Dishonest or clickbait-y subject lines, meanwhile, will do just the opposite.

Sure, tricking your subscribers may encourage more initial opens, but it won’t be long before readers will get annoyed, realising that the message isn’t what they thought. In the end, the opens gained will result in little more than a one way ticket to the “spam” folder.

And nobody wants that.

3) Lousy ROI

Image credit: 20th Century Fox


An email cannot be successful based on one element alone. All parts of the message, from the subject line to the purchase process on the linked website, help contribute to a robust ROI.

If one element of an email is lacking, a campaign will never realise its ROI potential. Simply put, poorly crafted subject lines will not result in revenue, and thus your return on investment will be low.

ROI on email campaigns tends to be some of the highest in the digital marketing sphere, so if you’re not seeing the ROI results you want, it’s time to carefully look at your campaign and what components are working or failing. Making seemingly small changes, like the underlying sentiment of a subject line, can make a big difference.

How do we know? Well, we’ve helped one ticketing website increase revenue by 417% on a single campaign!

4) Lame conversion rates

Image credit: 20th Century Fox


Subject lines should be designed to elicit the interest of, and ultimately engage, subscribers who are likely to convert.

A campaign for which resulting open rates are high might lead an email marketer to believe their subject line was spot on.

But not so fast…

If the campaign produced high open rates but few conversions, it either wasn’t targeting its audience in the right way and with the right offer, or its subject lines attracted opens from recipients who weren’t actually interested in what the body of the email had to offer.

Something didn’t match up.

5) Boost in unsubscribes

Ah, the dreaded ‘unsubscribe’.

How many times have lame subject lines caused recipients to unsubscribe from a mailing list before they’ve even opened the email?

It happens more than you’d think.

Off brand, boring, or spammy-sounding subject lines are bad news for everyone involved in the email marketing conversation.

If you’ve run a campaign that saw a higher than usual unsubscribe rate, then chances are you’ve missed mark badly somewhere in the process. In many cases, this may have happened before your emails were even opened, and it was all down to your sub-par subject line.

Feature image from: https://bit.ly/1cSfqBE

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