Perfecting Email Subject Lines for Ecommerce

Isaac Hayward
Isaac Hayward
HK Digital Co-Founder
13th December 2021

Today, on average, business’ email subject lines result in an average open rate of close to 21% across industries. While some companies have issues even achieving the average, we have an overall open rate of over 30%, and some of our subject lines have been performing far above that average.

Average Open Rate

Email subject lines for ecommerce are the first part of your emails’ anatomy that your leads see, which means that the subject line is your key to getting your audience to read the important body text that is aimed at conversion.

This means that you can have the highest converting copy in your body text, yet the subject line could be what chokes off your funnel before you even had a chance to communicate your value to your leads. 

I think we can therefore all agree that subject lines need to be strong, so I am going to explain the simple approach that we use to make sure we deliver our message.

The Foundations for Success

While our tactics are what will give you the tools you need to be able to create some really effective subject lines, there are a couple of strategic factors that you will need to consider in order to ensure that you start off with a bang and continue to optimize your approach:

  • Detailed target market research
  • A strong testing framework

If you read our article on creating an email marketing strategy, you already know how important these factors are.

Without fulfilling these crucial steps, you will essentially be running blindly into your challenge and will have a hard time quantifying any of your results moving forward, so let’s quickly review what is necessary to set up a good foundation for open rate optimization.

Target Market Research: Understand What triggers Your Audience

When researching your target audience, you will want to have a good understanding of all of the personas that you intend to target with your email campaign.

Here are some of the most important target market characteristics to consider for the sake of subject lines:

Email Target Market

While sending your emails at the right time on the right days isn’t necessarily going to change the copy in your subject lines, it is crucial to your open rate and, therefore, should not be overlooked. 

Pain points and gain creators are going to tell you what kinds of subject matter to use in your copy, and the kind of language that they use in email correspondence will tell you how to frame those pain points and whether Grammarly will give your text a smiley face or handshake emoji.

Once you have a good understanding of your audience, you are prepared to start properly utilizing the tactics that we use to optimize our subject lines for higher than average open rates.

Testing: The Key to Open Rate Optimization

As always, we have to touch on testing, as this is how you keep track of what works and ensure that your subject lines only get better. If you read our article on building a growth plan, you already know how to set up a simple testing framework, so I’ll just give you a quick review on a simple approach:

  • Create 2 unique subject lines and run them in tandem,
  • Assess the open rate spread between the two subject lines after each has been sent at least 50 times,
  • If no clear winner, continue until a clear winner is obvious, 
  • The winner runs as you test the rest of your email’s anatomy,
  • Create a new subject line and test it against the previous winner to restart this process.

Pro tip:

Keep track of the tactics that were used in each unique subject line so that you know which tactics win. Ideally, you will want to substitute one tactic from your winners in your new subject lines as you try to beat them.

This way, you can get a handle on the tactics your audiences respond to and further refine your buyer personas.

Our 3 Favorite Tactics: Your Weapons in the War on Attention

Remember the market research we were discussing? This is where that really begins to shine. The tactics that you use to persuade your audience to open your emails are very closely linked to the psychological profile or persona of your customer.

So, while I am describing our successes with these tactics, remember that the way in which you use them might differ quite a bit from our case.

There are plenty of tactics out there, and we have tried them all, but we are going to focus on what we know works well: the stuff that keeps us over 30% open rates.

Before we jump into the tactics, remember that subject lines have a couple of minimum requirements before the tactics can truly be put to their best use:

  • Word limit: Try to keep it to 4-5 words so mobile users view the whole line,
  • Showcase your value: Your company solves some customer pain points. Be sure to leverage them in your subject line,
  • Stay away from spammy sales language.

Now let’s see what you can test as you push your open rate to the moon.


Personalization is probably the most discussed tactic in email marketing, and that is because it worlds quite well. 

By simply adding your contact’s name in the subject line, they are immediately more likely to pay attention: they have spent their entire lives, from birth, being trained to respond to the sound or sight of their name.

This can be especially amplified if you are targeting professionals. However, in our case, we found that mentioning the company name in the subject line is far more potent than the contact’s name. 

Why is this? As we are primarily trying to gain the interest of company leaders, our target persona is extremely concerned about their business: they live and breathe business and generally hold their business’s performance above themselves!

The takeaway: Use personalization wisely: what is it about your audience that will spark the most emotional response?

Fear and the Sense of Urgency

Using emotion to spur action in your audience is not anything new; businesses have been doing it for… well it feels like forever at this point.

Now this might sound unethical, but in practice, it really doesn’t do any harm and your audience will have no idea you had this in mind if you do it right: you can utilize our natural aversion to risk/loss in order to boost the emotional response to your subject line. 

Why the negativity though? Using negative emotions, in general, is more effective when getting people to act. This doesn’t mean that you need to think about how to terrorize your leads, rather, simply that you need to appeal to the customer pains that you uncovered in your market research.

As we are a marketing agency, we found that the main value that our audience would be concerned with is… you guessed it: sales!

When sales go up, we are pretty happy, but when sales decrease, the world is ending. Here’s an example of one of our best subject lines:

“Is {company_name} making enough sales?”

Nothing too flashy or obvious that we were trying to trigger any kind of emotion and, if it worked, they are reassessing their company’s current growth rate and wondering how much better it could be: time to open this email and find out what these people seem to see…

Questions: Use ‘Em

You may have noticed that our million dollar subject line was in the form of a question. This is no mistake.

We have tested many subject lines and have found that our audience doesn’t take too well to people telling them what is up with their company, or what they need to do. 

But this isn’t just a winner in our market. Much like the concept of personalization by name, people are trained to automatically respond to queries. 

After testing subject lines with and without the question format, holding the content constant, we found that those which were not framed as questions performed right around the global average open rate (22%), which is still just above the standard for our target audience.

However, those framed as questions were consistently above a 30% open rate, reaching up to as much as 45%.

Key Takeaway: Are you using questions in your subject lines or not? Hopefully, the answer is yes!


Sure, there are quite a few more tactics out there, and you can bet that we are going to cover all of them in the near future, but these three tactics were the key to us consistently turning out a continually increasing 30% average open rate.

Just keep it short, target the most important customer pain points, use the personal information and pain points and framing in a way that is most likely to spur thoughts of risk and loss, and ask a question that they are instinctually forced to notice over the rest of the ‘spam,’ and you are set to start with a high open rate that you would be satisfied locking in for life.

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