Subscribe To The Newsletter

Insights delivered straight to your inbox! Receive news & updates from Seamless.AI

By submitting this form, you agree to the Seamless.AI Terms of Use & Privacy Policy

Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.


min read

Mastering the Art of Subject Lines: Choosing Ones that Convert

Seamless.AI icon logo
Seamless.AI Team
June 2, 2023
Email subject lines that convert

Email subject lines hold immense power, in both sales and marketing.

They are the gatekeepers, determining whether recipients will open or ignore your emails.

If emails were a dish, subject lines would be the essential ingredient to the recipe. Essentially, subject lines are actually more important than the content.

Why? Because subject lines determine whether or not the recipient opens the email in the first place. Over half of email recipients decide to open an email based solely on the subject line. 

So if you want to increase the chances of getting those emails opened, it’s important to craft a unique and enticing subject line every time. 

They can also save your email reputation from SPAM reports on your domain. 

Approximately 7 out of 10 readers will report an email as SPAM after reading just the subject line.

Avoid SPAM trigger words like free, click, no cost, price, money, or give away because these might cause your email to get blocked by the recipient's filters. 

In this blog post, you'll learn:

  • Key strategies to help you choose subject lines that drive higher open rates boost your conversion rates
  • 5 Easy ways to improve your overall email campaigns
  • Hacks to increase your email open rates

Mastering the art of subject lines that convert

Know your audience

Before you even think about writing a subject line, take the time to understand your target audience. Analyze their demographics, preferences, and pain points.

What motivates them? What language resonates with them? By knowing your audience inside out, you can tailor subject lines to address their specific needs and desires. Personalization is key, as it creates a sense of relevance and connection.

Keep it concise and clear

In today's fast-paced digital world, attention spans are short.

To capture your recipients' interest, your subject lines need to be concise and clear. Aim for brevity, ideally keeping your subject lines under 50 characters.

Ensure the message is easily understandable and gets straight to the point. Avoid jargon or overly complex language that might confuse or deter your audience.

Create urgency and FOMO

One effective technique to boost open rates is to create a sense of urgency or Fear Of Missing Out (FOMO).

Use action-oriented words and phrases such as "Limited Time Offer," "Last Chance," or "Don't Miss Out." By instilling a sense of urgency, you encourage recipients to take immediate action, increasing the chances of conversions.

Spark curiosity and intrigue

Humans are naturally curious creatures.

You can leverage this innate curiosity by crafting subject lines that pique interest and spark intrigue.

Pose intriguing questions, provide teasers, or make bold statements that leave recipients eager to find out more. However, be sure to deliver on the promise within the email content to maintain trust and credibility.

Experiment with personalization and segmentation

As mentioned earlier, personalization plays a crucial role in subject line effectiveness.

Utilize the data you have about your subscribers to personalize subject lines whenever possible. Include their first name, reference their previous interactions or purchase history, or even use dynamic content based on their preferences.

Additionally, segmenting your email list allows you to target specific subsets of your audience, enabling you to tailor subject lines to their specific interests and needs.

A/B testing: your secret weapon

A/B testing is an invaluable tool for optimizing subject lines.

Split your email list into two groups and send each group a different subject line. Measure the open rates and click-through rates to determine which subject line resonated better.

By continuously testing and refining your subject lines, you can identify the strategies that work best for your audience and improve your conversion rates over time.

Analyze and learn from data

Data is the fuel that drives effective email marketing campaigns.

Pay close attention to the analytics and performance metrics of your email campaigns. Identify trends and patterns in subject line performance.

What subject lines have consistently led to higher open rates? What types of subject lines have failed to engage your audience? By analyzing this data, you can gain valuable insights that will inform your future subject line choices.

5 Easy ways to improve your email campaigns

As salespeople and marketers, most of us have written emails that were not only forgotten, but completely ignored.

Sometimes we get so wrapped up in the technology behind our email campaigns, that we forget to analyze and improve the content or strategies.

The truth is, if you're not sending emails that people want to open and click, then you won't generate any sales. 33% of people open an email based on the subject line alone. And 69% of people report emails as spam based on the subject line.

So how do you get people to open and click on your emails? You write subject lines that capture the subscriber's attention.

Here’s how:

1. Keep it brief.

No more than 60 characters. Aim for 41 characters to ensure each word appears on desktop, mobile, and tablet devices. 

2. Personalization is key.

This might not seem like it has a major impact, but data shows that personalization can increase revenue results on average by 20%.

3. Prioritize the prospect.

Instead of pitching your product (which you can do in the email body), write a subject line that captures your prospect’s interests and speaks to their goals, dreams, desires, and paint points. 

4. Create urgency.

Language like “Act fast” or “X deal expires soon” will get your email opened because no one wants to miss out (Fear of Missing Out or FOMO is real). But don’t overdo it. Too many urgent requests will get you blocked or unsubscribed. 

5. Leverage social proof.

Dropping social proof validates your solution as a proven commodity. This can inspire confidence in the prospect to the point where they’re ready to act without reading the email. Just make sure to segment your audience and present social proof that’s hyperrelevent to your persona. 

Your next email campaign can break records if you apply a few simple tweaks and take advantage of some well-known psychological hacks.

Start small, test, analyze, optimize, and test again and watch your open rates skyrocket.

Subject line hacks to increase open rates

Now that you know how to write email subject lines and how to improve your email campaigns, here are a few hacks you need to know to avoid the SPAM inbox, create intrigue, and get those prospects to click. 

Subject line hack #1 - The human negativity bias

People are naturally drawn to the drama of negativity. We’re hardwired to remember the negative responses more than positive responses.

Use this fact to your benefit by appealing to human negativity bias in your subject lines. 

Phrases like “This is why 99% of people fail at___,” “The TRUTH they don’t want you to know,” “You’re doing ___ wrong,” “Worst ideas that cause people to___,” or “My awful experience with bad data” are all buzzy subject lines that catch your attention. 

These are great examples of how you can lean into that human negative bias and appeal to people’s desire to improve at the same time.  

Subject line hack #2 - Don’t be passive, give a call to action

Another way to increase open rates is by including a direct call to action in your subject lines.

Take a look at these two examples of subject lines:

I thought you might want to take a look at this
Don’t miss these tips {Insert first name here}!! 

Of the two, the second subject line stands out more because it’s a direct call to action that generates curiosity. 

The first line is way too passive and has no urgency. Words like maybe, possibly, might, perhaps, suggest, and could are all examples of passive, vague language that you want to keep out of your subject lines. 

Make the reader feel like they have to open your email by being direct and straightforward with your subject line. 

Subject line hack #3 - The perfect number of characters

What’s better, a short or a long subject line? This is an ongoing debate amongst email marketers. And it turns out there is an ideal amount of characters you want to leverage to increase your open rate. 

MailChimp claims that a subject line with less than 60 characters is ideal, with 9 being the least amount of characters they suggest using. Others say that less than 40 characters is best, and if it fits in the preview, even better. 

We’ve found that the perfect sweet spot is 6-10 characters. This range gets the highest open rates!   

Stick to that 6-10 character range and make sure your subject line is mobile-friendly by sending a draft to your phone. If the full subject line fits in the preview you’re golden. If the line gets cut off, shorten your subject line.  

Elevate your email game with these 3 subject line secrets to improve your open rates, test them out and see for yourself why subject lines are so important.


Crafting subject lines that convert is both an art and a science.

By understanding your audience, keeping your subject lines concise, creating urgency or curiosity, personalizing and segmenting, A/B testing, and analyzing data, you can continually improve your subject line effectiveness.

Remember, subject lines are the gateway to your emails—make them captivating, relevant, and irresistible to increase open rates, engagement, and ultimately, conversions.