Trying to come up with a subject line from thin air is a great recipe for writer's block and frustration. Using a formula is much easier and helps get the ideas flowing.
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Creating subject lines is one of the most stressful parts of email marketing.
And the reason why is obvious...
Your subject lines have a huge impact on your open rates. You know they can make or break your email campaigns and that pressure leads to anxiety and writer's block.
But the real problem is that most people lack a clear and effective process for creating subject lines.
Where do you start? What tactics can you employ? How can you gauge whether a subject line is good or not before you send the email?
Knowing the answer to these questions would alleviate a lot of stress and make the whole experience easier, wouldn't it?
Unfortunately, most other articles that promise to teach you how to create subject lines fall short.
Some promise to teach you subject line formulas or tactics. But they give you no guidance on how to pick the best formula for your specific email. And many of their formulas are email-specific - they only work if you're sending a certain type of email (I've seen many articles share things like the "How-To Formula", which only works if you're sending a how-to email).
Other articles share subject line "best practices." But while those best practices are accurate, they're not helpful for creating subject lines from scratch. Advice like "keep your subject lines short" doesn't give you any direction for your subject line.
Another type of article I've seen is the subject line example compilation - a big list of examples of subject lines. Which is great. But I'd bet you'd like to know how those people came up with their ideas so you could do it yourself.
We aim to succeed where others have failed. While we'll share subject line formulas, best practices, and examples, we'll also cover:
So don't waste any more time. Read on and learn everything you'll need to become a subject line creating machine and never struggle with subject lines again!
NOTE: This guide clocks in at over 10,000 words. So feel free to skip around to whatever applies most to you. At the end of the article, we've compiled one big list of every subject line example we share (140+ examples) as well as a FAQ.
The more email subject lines you create, the better you'll get. And eventually, you'll develop your own process for creating them as well as an intuitive sense of what works for your business and audience.
To get to that point, you should start by following a proven process for creating killer subject lines that get opened.
We'll dive deep into each step of the process later in this guide. But let's start by going over the entire process so you know what to expect and how to apply it.
Email marketing is all about goal completion - getting your subscribers to complete a marketing objective.
There's the overall goal of your email strategy, which is usually to increase business revenue by generating sales.
But every email you send has a smaller goal of its own. Each email should have an effect on your audience or inspire them to take an action that leads toward the overall goal of increasing revenue.
Some emails aim to nurture subscribers with great, useful content. Others aim to recover lost sales from customers who abandoned carts.
A great subject line facilitates those goals by communicating the value of the email and setting proper expectations.
So, to write great subject lines, you must start by getting crystal clear on what the goal of each email is.
Nobody says you need to come up with your subject line all by yourself.
To quote the famous screenwriter Aaron Sorkin: Good writers borrow from other writers. Great writers steal from them outright."
Luckily, there are a whole host of proven formulas you can borrow to brainstorm and create killer subject lines.
Later, we'll share a list of those proven formulas and provide multiple examples of each to inspire you as you write.
While there are many other articles that compile them, they all fail to mention a critical component of using subject line formulas: matching the formula to the goal of your email.
Some formulas won't work well with the email you're sending. Worse yet, some formulas can work against your email and hinder goal completion.
So we'll also discuss how to match formulas to goals and tell you which formula works best with which types of emails.
In our research for this article, we've come across many articles that share "subject line best practices."
But many of the best practices they share don't apply to all subject lines.
For example, this article on subject line best practices from agilecrm tells readers to use numbers in their subject lines. Apparently, there's data showing that subject lines with numbers perform better.
But using numbers in every subject line is arbitrary and unnecessary. That's not a "best practice", it's just an idea that can work well in some emails.
Best practices should be universal. More importantly, they shouldn't be used to create subject lines. They should be used to polish and improve subject lines.
In this guide, we'll share universally applicable best practices that will make your subject lines shine.
After you've selected a formula that works for your email and brainstormed ideas for subject lines, you can use our best practices to make them the best subject lines they can be.
Step 4 is perhaps the most important step to creating subject lines that get opened.
Just because a formula or practice worked best for one company, doesn't mean it will work best for yours.
Your audience is unique. And they're the ultimate barometer for whether a subject line works or not.
That's why you must A/B test your emails.
A/B testing is the process of testing your subject lines with separate but similar members of your audience. You create 2 different subject lines for the same email, send them out to separate but similar groups of your audience, and see which performs better.
A/B tests can be used to help you decide which subject line idea to go with. For example, if there are 2 subject line formulas that you think can work well with your email, you can create an A/B test to see which performs better.
They can also be used to test smaller tweaks to your subject lines to see if those tweaks improve open rates.
Not only will you learn which subject line is better, you can use data from your tests to improve subject lines.
But the key to pulling this off is to run proper A/B tests. If you don't, you'll corrupt your data and make bad decisions. Which is why we have an entire section of this guide devoted to discussing A/B tests and how to run them.
After identifying the best subject line, you can finally run your campaigns.
But good email marketers should always be improving. Even if your open rates are good, they can always be better.
So in our last section, we'll discuss some ways to improve upon your subject lines moving forward.
To help clarify each step, we'll apply them to a fictional email campaign for SEMRush - a tool that specializes in keyword research, competitive analysis, and Google campaign optimization.
The whole purpose of email marketing is goal completion. Before you start coming up with subject lines, you should take some time to get clarity on your goals.
Start by answering a few simple questions about your goals. The answers to these questions will provide the raw materials you'll use to construct your subject lines.
There are many different types of emails, each with a particular goal.
The goal of a Welcome Email is to get your new subscribers/users set up properly so they can get the most value out of your emails/products.
The goal of an Abandoned Cart Email is to convince shoppers to complete their purchase.
The goal of a Nurturing Campaign Email is to develop your relationship with your subscribers and move them through your sales funnel.
But when answering this question, it's important to get very specific. You'll need those specifics later when creating your subject line.
To make this clearer, let's apply it to SEMRush.
One of SEMRush's marketing segments is Content Marketers who use their tool to come up with ideas for content.
To help this segment get the most value from SEMRush, they want to send an email that introduces users to their Keyword Magic Tool - a feature of the software that enables users to find millions of keyword suggestions and discover long-tail keywords to target.
Then the goal of this email would be:
“to help Content Marketers get the most value from our software by introducing them to the Keyword Magic Tool.”
Next, you should outline how the email will accomplish this goal.
In other words, what benefit does the email provide and how will it influence subscribers to take the desired action.
For SEMRush, their email will help users utilize the features of their software that will benefit them most.
So their answer to this question is:
"by teaching Content Marketers how to use the Keyword Magic Tool to find keywords to target and create content ideas.
To answer this question, create a list of the subject line formulas you think will work with this email.
In the next section, we'll outline proven subject line formulas that can increase your open rate. We'll also describe the types of emails those formulas work best with.
After you've determined which formulas work with your email, you can use them to brainstorm a bunch of examples. Later, you'll pick the best ones to polish up and test in Steps Three and Four.
For their email, SEMRush might consider applying the
“Pain-Point Formula, Greed Formula, or
Straightforward Formula.”
Now that you have the raw materials you'll use to construct your subject line, it's time to apply those raw materials to a subject line formula.
You may worry that using subject line formulas is too cheesy or hackneyed.
Trying to come up with a subject line from thin air is a great recipe for writer's block and frustration. Using a formula is much easier and helps get the ideas flowing.
Each formula below taps into universal human needs and habits that affect us all whether we're aware of them or not.
If you want to create subject lines that get opened, you should model subject lines that get opened. Or at least start with successful models and improve upon them later.
While the subject lines you create from formulas may feel stale and overused at first, you can edit them and make them shine in the polish phase (Step Three). Ultimately, your aim is to create subject lines that you can use for A/B tests and let your audience tell you what works for them (Step Four).
Consider these formulas to be exercises that'll strengthen your subject-line-creating muscles. Soon, you won't need them and you'll be able to create subject lines all by yourself. Perhaps you'll even create new formulas of your own.
Below is a list of proven formulas you can use to create killer subject lines. Each has a description of what the formula is, why it works, how to create them, and examples you can use for inspiration.
Familiarize yourself with each formula. If you want, use them to practice creating subject lines and develop your skills.
When in doubt, go with the easiest and simplest subject line tactic - the Straightforward Formula. The Straightforward Formula is exactly as it sounds: a plain and direct description of what the email is about.
The SEMRush email we discussed earlier is an introduction to their Keyword Magic Tool. And it's valuable to their targets because it helps them find great keywords for content.
There are two reasons this tactic works well.
First, it gets straight to the point. It immediately tells subscribers what to expect and why it's valuable or interesting. In today's busy world, time is of the essence.
Second, it works well on mobile. More than 70% of people check their emails on a mobile app. Most mobile screens display only 30-40 characters of a subject line. Getting straight to the point ensures your subject line won't get cut off before it hooks them.
The Promotional Formula involves creating subject lines that hook subscribers with an enticing promotion, like a discount, special sale, or new product.
Obviously, it only applies if you have a promotion to share.
But if you do, creating a subject line that advertises the promotion is a great way to grab your audience's attention and get the email opened.
When creating any subject line, it's always important to communicate the value of the email no matter what formula you're using.
But with a promotional subject line, the promotion itself is the main feature. WHAT you're offering is secondary to the fact that you're offering some kind of deal or promotion.
Because the promotion itself is what grabs the audience's attention and influences clicks.
This may seem like a trivial issue, but understanding it is important to properly constructing promotional subject lines.
Step 1: Write down what you're offering in the email (a special deal, discount, product bundle, or limited-time offer).
Step 2: Add relevant promotional keywords ("new", "discount", "offer", "special", "deal", "sale", etc.) to the subject line.
Step 3: Highlight the promotional keywords by putting them as close to the beginning of the subject line as possible and/or using all-caps, bold letters, asterisks, etc.
Then they could apply the Promotional Formula and create subject lines like:
NOTE: Be careful when using promotional keywords. Many email clients flag promotional keywords and mark the emails as SPAM. So make sure your subscribers add you to their email contacts. And try not to overuse promotional keywords.
The Promotional Formula works by using a promotion to grab attention and pique curiosity.
People are always on the hunt for a good deal. So when they see promotional keywords, they instinctively pay attention and stop to check it out.
If they're interested in buying the product you're promoting, then they'll definitely be interested in your email.
But even if they don't necessarily need the product right now, the idea of getting a great deal on it might be enough to convince them to buy or, at the very least, open your email.
Which is why you must call attention to the promotional keywords you use. They do the real legwork in promotional subject lines.
The FOMO/Scarcity Formula capitalizes on our fear of losing something - a discount, valuable products, a great event, products that are selling out fast, etc.
These subject lines share an offer that expires soon and must be acted upon quickly.
It's basically the Promotional Formula with a deadline attached to compel subscribers to take action quickly.
While they're most often used in Sales Emails, they can also be used to promote other aspects of your business, like events and product bundles.
To apply the FOMO/Scarcity Formula:
SEMRush could create FOMO/Scarcity Formula subject lines like:
FOMO/Scarcity Formula subject lines work for the same reasons as Promotional Formula subject lines.
But they're even more powerful because they combine our natural fear of missing out with a concept called Parkinson's Law.
Parkinson's Law is a concept that states that any task will take up as much time as you allow for it.
In other words, if you give yourself 1 day to complete a task, you'll get it done in 1 day. But if you give yourself 1 week to complete a task, then it'll take a week.
People are more likely to take action if a looming deadline approaches. Like students who put off doing a project until the day before it's due, then work through the night and somehow manage to get it done.
The same principle applies to shopping. People may want your product, but if they think they have an unlimited amount of time to buy it, they'll put it off.
Or if they think the cart they abandoned will be waiting forever, they'll put off checking out.
But if they know something will only last for a limited time, then they'll act quickly.
Curiosity is a powerful marketing tool. That's why it's used in so many headlines, emails, and other forms of marketing copy.
The Curiosity Formula involves creating subject lines that get your audience curious about the contents of your email.
While you can create curiosity by asking questions or promising something interesting/valuable, the most powerful way to create curiosity is by utilizing information gaps.
As humans, we have a psychological need for complete information. Incomplete info can drive us crazy and we'll feel compelled to complete it.
You can capitalize on this human need by creating subject lines with information gaps - incomplete or missing information.
Let's take a look at three different ways you can create subject lines with information gaps: the Cliffhanger Gaps, the Relative Gaps, and the Open-Ended Gaps.
Emails Promoting Blog/Marketing Content SalesEmails
The Cliffhanger Gap involves creating subject lines that tease the audience with a hint of what's to come without giving them the full picture.They'll want to know what happens next.
There are three types of cliffhangers: promise-based, question-based, and event-based.
A promise-based cliffhanger is a subject line that promises something if you read the email. Every how-to subject line promises to teach you something if you read the email.
Example: "How to make $100K in one year."
A question-based cliffhanger is when your subject line asks a question that is answered in the email. To learn the answer, readers have to open it.
Example: "Who Is More Active On Social Media: Men Or Women?"
An event-based cliffhanger describes a series of events without providing the conclusion. To learn what happens, readers have to open the email.
"We asked 100 marketers how they track ROI. The answers will amaze you."
The Relative Gap involves giving the audience two or more pieces of information without a full explanation of how they're related. The audience will feel compelled to connect the dots.
AWAI once sent out an email to their audience of writers with this subject line "What a cat can teach you about living the writer's life".
The reader is left wondering how these two seemingly unrelated things - "cat" and "writer's life" - are connected.
The Open-Ended Gap involves creating attention-grabbing but vague subject lines that create many more questions in the reader's mind.
If done right, they'll have so many questions they won't be able to stop themselves from opening the email.
A subject line like "We want to send you an awesome gift!" is an example of an Open-Ended Gap.
It leaves the reader with so many questions. What is the gift? Why is it so awesome? Why do they want to send it to me? What's the catch?
Human beings have a natural instinct to acquire information. At one time in our history, that impulse saved our lives and guided our evolution.
The need still exists, and when presented with incomplete information, our brains feel compelled to complete it.
The Curiosity Formula seizes upon this natural instinct and uses it to capture an audience's attention and compel them to take action.
NOTE: This guide clocks in at over 10,000 words. So feel free to skip around to whatever applies most to you. At the end of the article, we've compiled one big list of every subject line example we share (140+ examples) as well as a FAQ.
The Funny/Clever Formula involves creating subject lines that are (you guessed it) funny and/or clever.
Funny/clever subject lines are just enjoyable. And if you can make your audience laugh, they're likely to open your email out of appreciation and a desire for more humor.
But these subject lines can also stand out among the other subject lines in your subscribers' inboxes, make them like you, and build a stronger relationship. That likeability goes a long way toward influencing people to take action.
To apply the Funny/Clever Formula:
This is one of the hardest formulas to teach. Comedy and cleverness are difficult to teach and there's not really a direct formula for creating them.
The best way to learn how to create funny or clever subject lines is to collect and study examples of them from other emails. Then try to apply them to your own emails when the opportunity arises.
In addition to studying the examples listed below, you can also try the following tactics.
But the primary reason they work is the same reason humor works. Humor is based on a shared understanding of the world. To get a joke, you need to understand or have experience with the topic of the joke.
And if your experience is similar to that of the person making the joke, you'll find it really funny.
The connection these subject lines build with subscribers is not only great for getting them to open a particular email, it's also great for building your relationship with subscribers and getting them to open future emails.
Be careful. You must know your audience well to create funny or clever subject lines that land. You also have to be (at least somewhat) funny or clever.
You should always be looking for ways to personalize your emails and subject lines.
Why? Because emails with personalized subject lines are 26% more likely to be opened.
And they're one of the best ways to nurture your subscribers, learn more about them, and recover abandoned carts.
But the Personalization/Retargeting Formula goes beyond merely adding the subscriber's name to the subject line.
To properly use this formula, you'll incorporate the info you have on your subscribers and/or any aspect of your relationship with them into your subject line.
Methods:
To utilize this tactic, you'll need to incorporate surveys and other data capturing methods to build a progressive profile of your subscribers. Then create email automation programs to automatically personalize and send emails that incorporate this data into subject lines.
You can create retargeting emails that send to people who visit certain landing pages. The emails can share more benefits of that product to convince the subscriber to buy it, and the subject line can reflect that.
Or you can send retargeting emails to people who purchased a product that share products that similar shoppers bought.
Or you can create a survey for new subscribers that asks them what their major pain points are. Then personalize subject lines to reference those pain points in the emails you send.
The SEMRush emails we discussed earlier already utilize this formula. By sharing aspects of their products that each specific user will find most valuable, they're creating a personalized campaign.
As the book by WCW President Eric Bischoff says, "Controversy Creates Cash."
The Controversy Formula is simple: say something that shocks the subscriber so much that they'll feel compelled to click.
By shocking your subscribers with your subject line, you'll grab their attention and create curiosity. They'll want to know more and they'll want to understand why you're sending it to them.
Controversial subject lines are easy to come up with.
But to pull them off right, you'll need to be in tune with your audience's tastes and sensibilities. You'll need an intuitive understanding of what shocks them as well as how far is too far.
To create controversial subject lines, ask yourself:
Then find a way to connect the subject of your email to the things that your audience finds controversial or shocking.
For the SEMRush example:
Controversial subject lines work because they grab attention and create curiosity.
People are naturally drawn to controversy. Your controversial subject lines will stand out among other emails in your subscribers' inboxes and they'll be naturally drawn to them.
Then they'll want to know more.
SEMRush's subscribers don't expect to be insulted by the companies they subscribe to and they probably think they have solid content marketing strategies.
A subject line that insults them or triggers their fear of failure will capture their curiosity. At the very least, they'll want to know more about why they're being insulted and told that they're going to fail.
The Opposite Formula is similar to the Controversy Formula, but narrower in scope.
With the Controversy Formula, you're targeting anything that your audience finds shocking or controversial.
With the Opposite Formula, you're just saying the opposite of what your subscribers expect of you.
By subverting their expectations, you'll generate curiosity.
To apply the Opposite Formula:
To create this type of subject line, ask yourself:
Then brainstorm subject lines that do the exact opposite.
One easy way to apply the Opposite Formula is by sending out an email with no subject line at all. Upon analyzing their database of 6.4 million emails, Hubspot found that emails with no subject line were opened 8% more than those with a subject line.
Obviously, you can't do this with every email. But it's a great example that illustrates the power of doing the opposite of what's expected.
For the SEMRush Welcome Email Example, their users expect them to send an email showing them the best ways to use their product. They might try creating a subject line that does the opposite:
The human mind is programmed to look for patterns. By recognizing and understanding patterns, we can make predictions about the future and prepare for what's to come.
Things that behave according to the patterns we've come to expect is safe.
But anything that breaks with those patterns is potentially dangerous. The unexpected immediately stands out in our mind and we feel compelled to investigate it.
By doing the opposite of what your audience expects or what everyone else is doing, you'll break a pattern that they've come to rely on and trigger their natural curiosity.
Now that you've used the 8 subject line formulas to brainstorm ideas that match your email, it's time to ensure your subject line meets (as closely as possible) with proven subject line best practices.
Below are 6 best practices that apply to all subject lines. Use them to polish & improve your subject line ideas.
CURVE is an acronym used to create effective subject lines. It stands for: Curiosity, Urgency, Relevancy, Value, Emotion.
Every subject line should incorporate at least 1-2 elements of CURVE.
But the real key CURVE is using it to identify the core strength of your subject line so you can make it as strong as possible.
For example, if you're using the FOMO/Scarcity Formula, then Curiosity probably isn't important. Urgency is the most important part of that subject line formula. And you can increase its potency by increasing Value (emphasizing the value of your offer), Relevancy (making the offer more relevant to each subscriber/market segment) and Emotion (putting your subscribers in an urgent emotional state).
Weak Example: Sale: 25% off all products. Ends soon!
Strong Example: HUGE SALE: 25% off all Men's winter-wear. 48-hours left!
So analyze your subject lines according to CURVE. Identify their most important elements. Then use the techniques below to increase their potency.
Does your subject line invoke the subscriber's curiosity?
Even if you're not going with the Curiosity Formula, you can still include an element of curiosity to grab your subscribers' interest.
One easy way to add an element of curiosity to a subject line is by turning it into an open-ended question. If not, try adding a What-based or How-based content gap to it as described in the Curiosity Formula.
Does your subject line effectively communicate the value of the email to your subscribers? Does it include an offer? Does it target a pain-point or goal?
If not, ask yourself: what makes this email so valuable to my subscribers? Then figure out how to incorporate that value, implicitly or explicitly, into your email.
Does your subject line prompt subscribers to take quick action?
If not, try adding a deadline or an offer with a deadline to it
Is your offer relevant to your audience or the specific market segment you're sending it to? Does it make that relevance obvious and clear?
If not, try incorporating a relevant pain-point, goal, or interaction they've had with you into it.
People don't make rational decisions; they make emotional decisions and use logic to rationalize those decisions.
This is especially true when it comes to purchasing things.
Emotional language is great for grabbing attention and putting your subscribers in the ideal emotional state.
Try incorporating power words to boost the emotional impact of your subject lines and trigger emotional responses.
You can use power words to elicit:
For all the power words you'll ever need, check out Smartblogger's list of 801+ Power Words That Convert.
Try incorporating sensory words that connect to the 5 human senses:
For more sensory words, check out Smartblogger's list of 583 Sensory Words.
So ask yourself: what emotion do I want my subscribers to feel when they read my subject line?
Then brainstorm some ways to incorporate words that will feed that emotional state.
As with all writing, brevity is the soul of wit. So you should aim to cut your subject line down to as few words as possible.
Or rather, your goal should be to create the desired effect with as few words as necessary.
There are 2 important reasons to make your subject lines succinct.
First: fluff distracts from the goal of your subject line.
Novice copywriters tend to think that the more words they add, the stronger the effect they'll create. But in reality, you're just making your subscribers do more work and distracting them.
Second, you have a limited amount of time and space.
Most email clients display 60 characters or less of a subject line. And mobile, which more than 70% of people use to check emails, displays even less - about 25 - 30 characters.
So chop your subject lines down using these tactics.
Remove any word that isn't a necessary part of communicating the key features of your subject line.
Try removing any filler words. Filler words are words that your audience will fill-in without you explicitly writing them. Some can be removed altogether, others can be shortened or replaced.
These words include: that, and (shorten to & or +), or (replace with comma, backslash, or semicolon).
Also, look for any potential words you can shorten into contractions:
For every word, ask yourself:
Since you can't control how much of your subject line the audience will see, it's best to just put the most important information at the beginning.
BAD: Check out our latest and hottest items on sale at 25%+ off GOOD: 25%+ off our latest, hottest items. Act now!
The absolute worst thing a subject line can do is be misleading.
Misleading subject lines may get opened, but they set bad expectations and ruin the potency of your email. Once subscribers realize they've been misled, they'll view the email in a negative light and won't be persuaded no matter how good it is.
Misleading subject lines also have a far more negative impact: they hurt your relationship with your subscribers. After being misled enough times, subscribers will stop trusting you. They'll stop clicking on your emails and eventually unsubscribe.
There are 3 kinds of misleading subject lines:
This is where your subject line describes something entirely different than what's in the email.
If the subject line says "10 Tips On Creating Killer Subject Lines" but the email itself is a promotion for your email software, then it is egregiously misleading.
If the subject line says "10 Tips On Creating Killer Subject Lines", but then offers only 5 tips or the entire content is behind a paywall, then that is moderately misleading and subscribers will feel betrayed.
If your subject line says "10 Tips On Creating Killer Subject Lines", but then the email is in a different format (how-to;), then readers will lose a bit of trust in your subject lines and may be less inclined to click.
So for every subject line, ask yourself: "Does this email deliver exactly what is described in the subject line?"
If not, then you'll need to tweak it.
Wouldn't it be great if there was a tool that could tell you if you had a good subject line?
Well there is… and there isn't.
There are dozens of tools that will evaluate and grade your subject lines, many of them free. They'll even give you a score telling you how good it is.
But no tool can truly tell you whether your subject line is good or not. Only your A/B tests and audience can do that.
What these tools can do is analyze your subject line and give you data you can use to improve it. And they can give you ideas for A/B tests.
Omnisend's Subject Line Checker analyzes subject lines across different criteria, one of which is the wording. They tell you how many "Helpful Words" (words that increase open rate) your subject line contains and how many "Negative Words" (words that harm open rate) it contains and what they are. You can A/B test whether removing the "Negative Words" helps and/or which "Helpful Words" work best.
The Subjectlines.com Checker scores your subject line out of 100 and tells you which aspects of the subject line positively and negatively impacted the score. You can either make the changes it suggests or create A/B tests based off of those suggestions.
Different tools evaluate different criteria and weight those criteria differently. The same subject line might get a good score on one tool but a bad score on another.
Which is why you shouldn't rely on them entirely. Instead, test different subject line checkers to find the ones that give you the best, most useful feedback. Then use that feedback to improve and A/B test your subject lines.
For more subject line checker tools, check out this Hubspot article that shares 12 (most of which are free).
A/B testing your subject lines is the most important step to developing subject lines that get opened.
As we discussed earlier, your audience is the ultimate barometer for what works. Just because these formulas and best practices have a proven record of success, doesn't mean they're the best for your specific audience.
To figure out what works and increase your open rates as much as possible, you'll need to A/B test every subject line you create.
There are primarily 2 types of A/B tests to run:
You'll probably identify several different formulas that can work well for the email you want to send.
But which works best?
The only way to figure that out is to run an A/B test for both subject lines on the same email.
Returning to our SEMRush Welcome Email, they can probably apply the Straightforward Formula and the Curiosity Formula to their subject line.
Straightforward Formula: "Welcome: Find 1000's of keywords with our Keyword Magic Tool!"
Curiosity Formula: "Welcome: This tool will give you 1000's of keywords to target!"
They should create an A/B test to compare both formulas to see which one gets the most opens.
Test Tweaks
When polishing your subject lines, you'll probably come up with multiple different versions of the same subject line.
The only way to find out which tweak works best is to run an A/B test of the competing tweaks.
For instance, SEMRush could test two variations of the same subject line: one that emphasizes relevancy and one that emphasizes value.
Relevancy: "Introducing the tool that makes creating content 10x easier."
Value: "Introducing the tool that shaves hours off of creating content."
But you can also test smaller tweaks like:
No matter what you decide to test, it's important that you know how to run a proper A/B test. Otherwise, your data and your conclusions will be corrupted.
A proper A/B test will aim to control as many variables as possible. Both test subjects should only have one difference - the change to your subject lines.
This means you should:
You'll need a metric to compare both test subjects against in order to know which is better.
Ideally, you should stick to one metric: Open Rates.
Since the primary goal of creating and testing subject lines is to get emails opened, then you'll want to identify which subject line is getting the most opens.
You may also want to consider testing CTR.
If you're using the same email with both test subjects, but one is getting significantly more click throughs, then that may mean one subject line is setting up the email more effectively and increasing its potency. This becomes even more important if the Open Rates are similar.
Straightforward Formula: |
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Welcome: Get started with our Keyword Magic Tool |
Learn how to find great keywords with our Keyword Magic Tool |
Keyword Magic Tool: Learn about our most valuable feature |
Here's how to get the most value from SEMRush |
Create great content with our Keyword Magic Tool |
You've got a new message! |
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The 2016 State Of Social Report [47 Page Resource] |
Email Marketing Budgets 2020 Report |
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[Name of newsletter] - January 1, 2021 |
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5 products we think you'll love |
Curiosity Formula: |
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How This Student Made $100,000 In One Year |
3 Things That'll Scare You About How The Media Works |
Who Is More Active On Social Media: Men Or Women? |
How being lazy can make you a better marketer |
What a cat can teach you about living the writer's life |
The strange way millennials are saving the environment |
What Elvis Presley can teach you about email marketing. |
This tool makes creating content easy! |
The #1 tool for simplifying content creation! |
Save hours on content creation with this tool. |
You'll never have to do keyword research again… |
One tool. Millions of keywords. |
The tool that will forever change your content creation process. |
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How to create 10x more content with our Keyword Magic Tool |
How to save 10 hrs/month with Keyword Magic. |
How can Keyword Magic improve your content creation process? |
How can Keyword Magic save you 10 hrs every month? |
Open Keyword Magic. Enter your website. Then… |
Enter your website into Keyword Magic and watch what happens… |
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Promotional Formula: |
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NEW FEATURE: Check out our Keyword Magic Tool! |
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25% Off All Jeans |
Flash Sale Alert! |
A new product you need to have [promotion + curiosity] |
BOGO Alert: Our Summer Gear Is In! |
Priority Access: Our best deals on our Top Sellers! |
Christmas Sale! 20% off everything! |
4th Of July Sale: Huge discounts on your favorite products |
NEW: We've added 3 more lessons to the [name of course] |
Huge Discount: Get tickets to [event] ½ off! |
SPECIAL: 10 product bundles you don't want to miss |
FOMO/Scarcity Formula: |
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24 Hrs Left: Get 1-month trial of our Keyword Magic Tool |
Ending Soon: Save 30% On [Product] |
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Our products sell out fat! Complete your purchase before it's gone. |
Uh-oh! Your cart is expiring. |
Quick! We only have 20 [Product]s left! |
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You're missing out on points |
Last chance to get [product] 50% off… |
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Controversy Formula: |
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Why Your Business Is Going To Fail In The Next 5 Years |
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3 Reasons You Gave Up On Your Dreams |
Your Strategy Is All Wrong. Here's Why... |
You're Terrible At Content Marketing. This Tool Can Make You Great! |
This Tool Will Save Your Failing Business |
Your Boss Is Going To Fire You. Unless You Do This… |
Content Marketers Are Too Dumb To Do This Alone… |
Your Content Marketing Strategy Is Flawed. Use This Tool To Fix It. |
Everything you know about fitness is wrong |
Why your sales team sucks |
10 ways you're killing your dreams |
It's not your fault. You had bad parents |
6 foods you eat every day that are killing you |
Opposite Formula: |
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Don't Read This Email |
6 Reasons Why You Shouldn't Buy Our Product |
How I'm Going To Lose All My Customers & Wreck My Business |
6 Ways You Shouldn't Use Our Product |
3 Features Of Our Product You SHOULDN'T Use To Grow Your Business |
The Worst Way To Get Started With SEMRush |
3 Examples Of Customers Who Hated Our Product |
(No Subject Line) |
Want your business to fail? Read this email… |
6 ways you shouldn't use our product |
10 reasons to go with our competitors |
We've been lying to you… and probably will again. |
11 things we hate about our customers. |
"How we plan to go out of business in the next 5 years. |
The best subject lines are the ones that get opened, since that's their primary job.
Ultimately, you'll need to let your subscribers tell you what works by A/B testing subject lines and discovering what gets them to open emails.
But the best subject lines also share some common characteristics, including:
Brevity
Keep subject lines short so they don't get cut off in email clients. The ideal length for subject lines is between 30-60 characters.
CURVE
CURVE is an acronym for curiosity, urgency, relevance, value, and emotion. Your subject line should incorporate at least one of those (see Step Three section above to learn more).
Segmentation & Personalization
You should segment your email list and tailor your subject lines to each segment.
Honesty
Never mislead. Deception may work in the short term but it destroys your relationship with your subscribers. That, in turn, destroys your open rate and hurts your entire email marketing campaign.
To optimize for desktop and mobile, try to keep your subject lines between 30-60 characters and put the most important words at the beginning.
More than 70% of people check their email on a mobile device. While desktop email clients tend to cut off subject lines at around 60 characters, mobile email clients tend to cut off at around 25-30 characters.
So it's best to keep your subject lines short, and place the most important, attention-grabbing words at the beginning.
Email subject lines are important because they largely determine whether your email will get opened, ignored, or marked as SPAM.
According to research, 47% of recipients open an email based on the subject line alone. So if you want your subscribers to open your emails, then creating an effective, attention-grabbing subject line is critically important.
Just as important, 69% of recipients report email as SPAM based solely on the subject line. Getting marked as SPAM can hurt your delivery and open rates and jeopardize your entire email marketing strategy.
The easiest and most effective way to create subject lines, especially for beginners, is to use proven subject line formulas.
Start by breaking down the core elements of the email by asking yourself:
Then take those elements and apply them to a subject line formula that works for the email you're sending.
There are many formulas that have been used for decades to create effective subject lines. The best formulas work because they play to universal human needs and impulses.
Subject line formulas are great for brainstorming subject line ideas and developing your subject line creation skills. They'll provide you with subject lines that you can polish and A/B test so you can create subject lines that are perfect for your audience.
There are three key steps to increasing the open rates of your subject lines:
Start by using subject line formulas to brainstorm subject line ideas. The formulas listed earlier in this article capitalize on natural, universal human impulses and are proven to work.
Next, polish your subject line according to subject line best practices. Decades of email marketing have yielded lots of data on what works best with subject lines. You can use these best practices to optimize your subject lines and give them the best chance for success.
But ultimately, the only true way to increase open rates is to run A/B tests and let your audience tell you what's best. You should A/B test different subject lines and different versions of the same subject line to see what your audience is more likely to open.
There are many reasons an email may be filtered as SPAM. It can happen because of your subject line, the contents of your email, and/or your relationship with the recipient.
But when it comes to subject lines, the main thing is to avoid using SPAM trigger words.
Email clients have a host of words they associate with SPAM. If your subject line contains one or more of these keywords, or worse, if your subject lines frequently contain SPAM trigger words, they're likely to get marked as SPAM.
The problem is that many SPAM trigger keywords are words that we use often and/or you may need to use in your subject line. They include words like:
The real key is to develop a relationship with senders before sending them emails with potential SPAM trigger words in the subject line.
Start by prompting new subscribers to add you to their contact list so their email client recognizes you as a trusted sender.
Then send them a few non-solicitous emails that they're likely to open and enjoy to fortify your relationship in the eyes of their email client.
While those two steps should put you in the clear, you should still try to use SPAM trigger words sparingly.
Check out this list of 924 SPAM trigger words to learn what words you might want to avoid.