How to Write an Irresistible Email Subject Line

May 7, 2023

Whatever your profession, you can’t avoid writing email subject headlines. To grow your business, you’ll have to send cold pitches, warm emails, and collaboration requests. And listen to this, 47% of your clients will open your emails only if the subject line is good enough.

Source: OptinMonster

Yes, the email copy needs to do the job, but only if the subscribers read the subject line and click on it. In this guide, you’ll see how successful email marketers are doing it. We’re going to deep-dive into the strategies shared by the top copywriter Jacob Mcmillen, such as: 

Table of Contents

Top Qualities of an Irresistible Email Subject Headline

2-Part Objective of an Email Subject Headline

Part 1: Get the reader’s attention

Part 2: Get the reader to click

How to Write an Email Subject Line

Start Writing Compelling Subject Lines

Top Qualities of an Irresistible Email Subject Headline

I bet you don’t remember the last boring subject line you read. You don’t even remember who sent it. But a good subject line stays in your mind. It’s because it has one or more of these qualities:

A report shared by Litmus shows that iPhone and Gmail are the top two most used email clients. 

Source: Litmus

But longer subject lines are truncated on these email clients. If the readers can’t see the entire subject line, how will they read it?

So, you need to write shorter subject lines. But what is an ideal length of a subject line? Marketo conducted a survey and found that subject lines with 41 characters (7 words) got the most clicks.

Source: Marketo

Shorter subject lines work well because 1) they’re visible to the reader, and 2) they’re more punchy.

An average reader receives 126 emails per day. Do you think he reads all 126 emails? 

No. The reader scans his inbox and reads emails with attention-grabbing headlines. The rest go to the trash folder. 

My favorite example of an attention-grabbing email subject headline is this:


Source: Hubspot

The reason it got more attention is the opposite effect. It instructed the readers not to open the email but did it anyway, mainly because they were told not to.

As Oscar Wilde put it: “The public has an insatiable curiosity to know everything.” People have this innate desire to get to the bottom of things. 

Using curiosity, marketers achieved impressive results. For example, Kaleigh Moore, a world-class copywriter, got a 60.1% open rate using the email subject line “Did you write this?” 

If a headline makes a believable promise, it’s the best email subject line because it’s not gimmicky. For example, this simple email subject headline by Matt Diggity is a great promise.

It has these qualities:

Ensure your email subject lines have these qualities, and you’ll get better open and click-through rates.

2-Part Objective of an Email Subject Headline

So far, you’ve learned the qualities of a good email subject headline. Now you will learn to determine if it’s doing the job. 

An email subject line is doing its job if it follows this 2-part objective:

Yes, that’s all. It should do three things:

Let’s see how.

Part 1: Get the reader’s attention

Interestingly, the reader’s inbox is where the highest level of competition is. For instance, this is how it looks to an average reader.

If your email subject line is up there, it’s competing against 14 other subject headlines. And if the readers use mobile phones to read your subject line, they have the infinite scroll option.

Your headline must grab the reader’s attention from other headlines or whatever he’s doing. 

You can do this in a few ways:

Part 2: Get the reader to click

Your reader gives attention to many things, but he won’t give time to all of them. To get his time, you must hook them with the subject line. 

After seeing the subject line, he must read it and click on it.

So, how do you make the reader click on it?

Whatever it is, give a solid reason to get that click such that they open it and continue reading the email. And that’s where the job of a subject line is.

How to Write an Email Subject Line

So far, you’ve learned why to write a good subject line, what makes it effective, and its goals. Now is the time to learn how to write a good subject line.

You have to do nothing but fulfill the 2-part objective. 

Let’s get to it.

The first step is to grab attention. You can do it in these ways:

Catchy words like free, new, sale, etc., psychologically impact the readers. For example, this subject line includes “FREE TRAINING” to get the reader’s attention. These words attract eyes.

Or this email subject line that includes the word “sale.”

You can stand out visually from the rest of the subject lines to get the reader’s attention. Here are three ways:

All caps headlines stand out immediately. For example, this headline by Carly, a Pinterest coach, is different from the rest of the subject lines.

An even better way is to use emojis. Such as Alex Cattoni, a world-class copywriter, does when sending email newsletters.

The best tip is to use personalization. If you can add a personal element - your subject line is above others because you’re showing that you know the reader personally. 

To get the click, you must make your subject line strong. We have two main tools here:

Let’s look at the examples.

When you do the groundwork of finding the reader’s problem and getting its solution - a promise will do the most part.  

Check out all these subject lines by Jon Morrow from Smart Blogger:

All of them make a specific promise to Jon Morrow’s target audience: freelance writers.

Notice that none of the subject lines are genius or creative. That’s the benefit of making a promise. If it’s something the reader wants, tell them about it.

Another way to make them click is to generate enough curiosity so they can’t live without knowing it anymore. 

Here are great examples of curiosity-generating subject headlines:

All of these subject lines by Alex Cattoni create some curiosity. She gives a hint to make her subscribers curious. If they want to find out - they’ll have to click and read.

Start Writing Compelling Subject Lines

So, these are some strategies you can use to write irresistible email subject lines. 

Of course, the email copy should live up to the expectations. Otherwise, the subject line is nothing else but clickbait. 

You don’t want that. 

Remember, the subject line is just the barrier to entry. The crucial part is mastering the email copy. 

Your content should be valuable and live up to the promise in the email subject line. Give the reader what you promised and see your open rates skyrocket!

About the author: 

Ekta Swarnkar is a professional copywriter and content strategist. She helps online businesses optimize, startups build a presence online, and aspiring bloggers grow a blog. She shares her best tips on her personal website Follow more of her work over Linkedin or Twitter.

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