How to Write Catchy Email Subject Lines: The Ultimate

Email is an important part of the business, regardless of which profession or scale you are working on.

They have been shown to boost social media reach, drive sales and increase traffic as well as engagement. 

However, what you are putting in the subject line decides if the recipient will open the email or skip it. 

This can make your campaign ineffective and boring; that’s why it’s crucial to know why the subject line is important and what you can do to make it effective for your email.

Here is an ultimate guide that can help you in learning that. 


What Is the Subject In Your Email?

The subject line of the email is a single line of text that the person sees when they get the email from you. 

This one line determines if your email is going to get opened or if the recipient is going to send it straight to the trash. 

So make sure you are optimizing best towards the recipient. 

This is the first thing your receivers will see in their inbox; since email inboxes include a lot of emails per day, it includes different approaches that the brands want to get the attention of the audience, 

Because of this, having a catchy and clear subject line is more than important in an email. 

benefits of having good email subject line

Good email subject lines can create a powerful impact on readers; the words you choose can either encourage them to click and read the email or put it in the trash. 

So it depends on the subject line if your hard work on writing an email will pay off or not.

Writing a smart subject line can help in getting chances of ensuring the recipes do what you want them to do and also improve the success of email campaign results. 

Why Does Subject Line Matters In Email, And How Does It Affects? 

The subject line of your email works similarly to the cover of a book or the headline of the article. 

With an effective subject line, it compels your audience to click on the email and read it.

If it’s not on point, there are high chances they will simply ignore and your offer, content, and links will go straight into their trash. 

Just like digital content, the subject line requires striking a balance between being intriguing and informative. It should induce the recipient to click but not over or under-promising what’s inside of the email. 

If it’s not representing what’s inside the email accurately, it will be judged depending on that. 69% of email recipients report email as spam, depending on their subject line. 

So it will eventually strengthen the brand and motivate people to cliche even when the subject line is not strong. So you need to start new; make sure the subject line is funny, interesting, powerful, and smart. 

What Are The Characteristics Of The Good Email Subject Line? 

Invented by Alex Williams, creative director and digital strategy director at Trending Interactive, he created the approach called C.U.R.V.E. 

This allows him to create a subject line that is not just catchy but gets opened up every time. 

Well, the C.U.R.V.E approach stands for : 

  • Curiosity
  • Urgency 
  • Relevance 
  • Value 
  • Emotions

Based on this, a good email subject line requires having all five characteristics or at least two of the elements for having a high open rate. 

To understand in detail, it includes: 


A Lot of subject lines that stand out contain clear messages and tend to have much higher open rates. 

But maintaining a little secrecy can help in creating curiosity in the recipient and can make the subject line much more effective. 

The mystery tactic is known for piquing the natural curiosity in readers and integers. It makes sense as your recipient needs to have a reason behind why they should click on the email.

However, when you are considering this, make sure you are aligning it with your brand persona, target audience, and tone as well as voice. 

Don’t end up misleading your recipients or tricking them; it can badly backfire. 

Also, your email might end up in spam which damages your reputation. 


Create urgency when you are writing the subject line in your email. 

You can use this strategically for creating the email subject lines, which leads to better responses.

For example, communicating at the end of the sales or promotion, so you can improve the chances of getting your recipient to go through the email at least once. 

Urgency can be created. However, you need to stick relevant to the subject line, which includes : 

  • Discount or special offer
  • Free live events like a webinar
  • Training program or product that comes with limited time only
  • A limited number of items or shops for sales
  • Tips or news related to current situations and events.

Make sure that using it is associated with value and relevance; it stays powerful and helps you in improving situations.

Besides that, make sure you are clarifying the subject line, converting the urgency and powerful language. 


Whenever someone subscribes to an email, the purpose is to keep it more informed and the latest happenings or learn about a particular topic. 

So depending on the subject line, this should be based on trending topics of the ongoing events and interest, helping in establishing the brand identity and authority within the specific industry. 


Subscribers always look for value when it comes to email and always offer in the email. 

Whenever you are writing the subject line, ask yourself a question to yourself, if you were the recipient of the email, what value would you be looking for in the email?

There are different things that can be included, including experiences, cool offers, new things, discounts, and content that is related to it. 


It’s nothing new to say that people respond to decisions based on emotions. Depending on what triggers the emotions, this can help encourage them to take action and read the email. 

One of the best ways is using sensory language. To do that, you require the use of the right words and connecting with all the five senses related to humans, including sight, sound, taste, touch, and smell. 

What Are The Elements Of An Effective Subject line? 

Email marketing is one of the effective ways that can help in marketing the business directly to clients. Also, the cost is relatively low. 

However, in order to build an effective subject line, you need to consider the basic elements first. This includes : 

Motivation To Open The Email 

The main purpose of writing an effective email subject line is to make the recipient click on the email and check the message. 

Also, it’s important to keep in mind that on a daily basis, your customers are getting tons of promotional emails. 

The majority of emails either get deleted, lost, or ignored. The subject line often decides the factor if the email will be opened or removed. 

When you are writing the subject line, make sure you are giving the reason behind why they should click on the email and also what will be inside that is going to help, including special tips or discounts. 

The subject line should be attention-grabbing and encourage the reader to click on the email. 

The first and most important element that you should not forget is motivation in the subject line.

Make Sure The Subject Is Relevant 

While some customers might click on the email as the subject line is advertising or announcing breaking news or once-in-a-lifetime sales. 

It’s counterproductive if the content is not suiting the subject line. 

When you are using the click bits, this makes your audience lose their trust and makes your brand image bad. This leads them to unsubscribe from the email list. 

If the email is not informative, it will be marked as spam.

One of the best ways that can help you is using light-hearted current events, seasonal holidays, trending topics, etc, in the subject line. 

Also, such topics appear relevant and appeal to subjects that are directly on the customer’s mind. 

It can be fun, and also you can make it more engaging. 

What Are The Types Of Subject Lines? 

There are different types that you get in the subject line. Also you can consider it for improving the chances of getting more clicks and leading to the benefits of email marketing. 

Here are some of the top types that you will get in subject lines : 

types of email subject lines

How To 

It might seem unimaginative and boring, but this one is considered a classic subject line. 

The method is effective as you offer the prospect a much more powerful guarantee.

What they are about to read is going to help them in teaching; it can be growing business, building personality, or learning skills. 

Not only are you offering the opportunity to learn, but also it helps in taking advantage of psychological principles.

Self Interest 

The next type of email subject line you can get appeals to the self-interest of the people, and people look for something better for themselves. 

They want to be better; it can be making more money, success with others, improving memory, etc. 

All of these are self-interest, and it can motivate much easier to click and improve the chances of getting better results. 

Quick & Easy Fixes

It’s related to psychological ideas, humans are naturally lazy, and the brain is wired in order to look for the highest return and the lowest investment. 

You don’t want to work out for months or years, so you look for a shortcut. So you can offer the solution in the subject line and improve the chances.

Some of the phrases that can be included in the subject line include: 

  • One skill
  • Simple tweaks
  • Easy ways
  • Simplest technique 
  • Deploy today
  • Four steps 


Scarcity in marketing capitalizes on the fear of missing something; it can be a fun event, a good deal, valuable resources, or a good deal. 

The scarcity type in the subject line helps encourage people to take fast actions instead of postponing them. 


Another type that you can consider, and it’s also useful in creating a subject line, can use the lesson on social comparison theory. 

So the comparison can help the audience to open the email and read the content. 


Curiosity is a useful marketing tool and holds a lot of value; it drives people to take action. 

However, the curiosity gap starts to close, which means people are getting immune to headlines that are overhyped. 

The sole reason behind this is fatigue which is caused when brands keep using curiosity over and over again. 

That’s why this type of subject line should be limited and only used when it’s needed. 

Not just that it should be related to the customer and have relevance to topics. 


The question helps in engaging with the readers; asking questions in the subject line can be powerful, but make sure your email contains the right answer or solution. 

This type of question can be asked when you know the pain point of your customer and have a solution ready for it. 


Another type that is a powerful driver for getting more clicks and actions can use the authority type email subject line for giving a valuable sign. 

Not just that, the authority should have its value and experience, so you are offering the right solution.


When you have something which is valuable and you can offer, make sure you are keeping it straightforward. 

Just finish the sentence with a straight line; this can help in better understanding, avoiding any kind of confusion or miscommunication.

If your content or solution is truly valuable, you don’t have to add a lot of fancies or generate crucify for letting people click on it. 


The next type you get is exclusivity; if your subscribers are part of an exclusive club, you can remind them in the subject line. 

People like it when they feel special; you can use this in your email subject line. Also, make them feel like they are on something that will help in making them feel special. 

Caste Study 

People like to read about case studies, especially for two basic reasons, including they want to know the proof or evidence on if there is any strategy or technique that works. 

How To Use Smart Formula To Write Killer Subject Lines? 

Although there is no right or wrong approach when it comes to sending emails since it depends on your audience. 

But here are three formulas that can help in creating a killer subject line and boost your click-through rate. 

Well, it includes : 

The Mutual Benefit Formula 

Well, the first formula you can consider is a mutual benefit; it is basically :

What Audience Want + What You Have = Mutual Benefit

Whenever anyone clicks on their inbox, they look for reasons for deleting the emails instead of keeping them, So you require to tell them and give a reason behind why they should open the email, and give them the appropriate subject lines. 

The Feel Valued Formula 

Well, the next one is the feel valued formula, which is basically : 

Personalized + the right tone = subscribers feel valued 

Personalization is important in email, but it’s even more when you are considering writing an effective subject line. 

Using the name of your recipient, location, or anything which is related to them and can add the personalization in email need to put in an email.

You can add the additional value from the pop-up or subscription in your personalization email, this implies that you recognize the receipt, and it connects you with them, with that help in building trust. 

High Open Rates Formula 

The third one is known as the high open rates formula; it is basically : 

Timing + Knowing The Audience = Higher Open Rates

So whenever you are sending the email, it’s best that you optimize the end times for the time zone when your readers are most interested. 

Prime sitting on the couch time in the eastern zone can be rush hours on the west coast, so consider the time before you send, and it will help in getting higher open rates.

What Factors Contribute To Email Subject Line Length Optimization? 

There is something you really need to understand right away before getting into the decision of the right email subject line length. 

And that has to be the fact that there is no such one-size-fits-all length for the subject lines. You need to identify and consider the factors which play a decisive role in email subject line length. 

So here are these factors you need to consider : 

The Devices And Email Services Your Emails Are Read On

It is no news that the number of emails that are opened on mobile devices is humongous. Statistically, accounts for 41.6% of the total opens. 

Not to mention, how dramatically these numbers are rising as well with more and more penetration of mobile phones in people’s lives. 

  • Even though almost half of the total emails are opened on mobile devices, yet, somehow 1 in every 5 emails that are sent is still not optimized for mobile usage. 
  • Mobile optimization for emails, whether it is in design or copy, is highly essential for the success of the email campaign. 
  • Well, it is true that mobile optimization is mostly about the design, the coding, or the template you are using, but it also has larger implications on the email subject lines as well. 
  • The kind of devices on which your emails will be read determines what length you set up for it. 
  • What you really have to do to get the best idea of the given length is test different lengths of subject lines and see what sticks. 
  • It is suggested to use email marketing platforms to run different test campaigns for doing A/B testing with multiple subject lines. 
  • See whether the short subject lines of 2-3 words or longer ones like 8-10 words are working for you. Make sure you don’t get conclusive with a few tests; rather, do it at different times. 

Another way to decide the subject email length is by utilizing the data to pinpoint what devices your subscribers are using. 

You may get data something like this, as this is statistics for the top 10 emails devices and clients in 2021, how many shares they have 

top email clients statistics

So, what does this tell you? 

Most of the email users are opening the emails on their iPhones and Gmail, so the subject line length you decide must be shorter. 

  • Because you wouldn’t want to break the subject line abruptly in-between, making your subject line less impactful or even meaningless. 
  • People opening their emails on their phones definitely happens in a portrait view giving a limited space for the subject line to appear. 
  • So perhaps, as per the device on which they are reading, the length here will be somewhere between 41 characters to 70 characters. 
  • For an iPhone, 41 characters is an ideal subject line length to read comfortably without getting a break in between. Similarly, 70 characters are for Gmail subject line lengths. 

What you must not do is have a long email subject line length that breaks and doesn’t appear in the preview completely, making it not impactful at all. 

How To Decide The Right Length For Your Email Subject Line? 

There is a study done according to Marketo that 41 characters or, say seven words appears to be the sweet spot for the email subject line length. 

For mobile devices as well as other desktop devices, it tends to be perfect as it works ideally for both.  

Also, what is notable here is that the right length for the subject email line, i.e. 42 characters, is basically ten characters less than the average subject line. 

The average subject line is the average of the overall email subject line lengths opted by the senders. 

Behavioral Aspect Of Email Subject Line Length 

When you craft your subject line length, you also need to remember how your subscribers are behaving towards your email, how they approach it, and how they read it. 

The behavioral aspect of reading the email will also determine the length of your subject line because it makes an impact on the conversion, open rate, or engagement rate of it. 

For example, if you are sending a subject line that is too long, detailed, and fairly predictable, especially in the given industry, your recipients are not even going to open it. 

This is because you’ve given so much away in the subject line itself. There is no sense of curiosity whatsoever for the audience to open it, even if you did have something good in there. 

The perception you make through your subject line also comes from its length. 

  • Most of the time, something shorter, snappier, and quickly said has a bigger impact, such as “ You will fail.” 
  • This just makes the reader curious as to what it possibly means, and even just to know that they will open it for sure. 
  • Your subject lines are also something through which your subscribers remember you and open your email. It also signifies your brand. 
  • Email subject lines are all about making people open the email and giving them some anticipation or preview/context as to what this email is about.

Make Your Subject Line Convincing 

It can be information, a pitch, a curiosity-infused line, a question, or so on. The key idea is to make it convincing that : 

  1.  They know what this email is about 
  2. Where this comes from or a brand identify it carries 
  3. They get compelled to open the email. 

Now, we will see how the length of the subject line applies to all these factors. 

Your email subject line length also helps to communicate the one key piece of information that is what your email is about. 

Now the short length of your subject line length must not make it incapable of informing the purpose of your email. However, it also does not share the burden it as well. 

The idea is to optimize your length in a way that still signifies the purpose, the aim, or the overall idea of what your email could be about. 

However, you must not compromise too much on the communication ability of your subject line to make it dramatically short or creative. 

Next is how your email subject line length carries your brand identity. Well, this is something that comes naturally to every email marketer or brand. 

Your email subject lines must be unique and have a common quality to all those like it can be identified by the recipients. 

For example, there may be a brand whose subject lines are always full of emojis. 

  • The length of the subject email lines plays a crucial role in the branding of the subject lines, making them more peculiar and easy to recognize. 
  • So, now you optimize the length according to your brand identity. Maybe your way always has been to send a question as to the subject line, so it can be 7-8 words. 
  • The key is to not go overboard in the length of the subject line, neither too small nor too big for the sake of branding, but definitely get creative in that range. 
  • The last but not the least aspect is creating curiosity in your emails through subject lines, making it so compelling that the recipient opens it. 
  • For that, email subject line lengths are also essential because it is always a challenge to make your subject line creative and curiosity-infused within the limitation of average or suggested email length. 

What Is the Best Practice For Your Overall Email Length?

So, just like the email subject line length, you also need to optimize the overall length or size of your email. 

Optimal Length of Your Subject Line Is More Than Word Count 

The average length suggested through snippets is said to be something in the range of 50 to 125 words, but it is more than just about the word count. 

When you talk about optimizing the length of the email, unlike the subject email line length, it is about the readability, flow, and overall quality of the email body. 

When you set the optimum length for the email, you cannot just write under 125 words and be all set in terms of optimization. 

It needs more work there. Every email is unique in its messaging, and if it is not, there is a far more complex problem you need to deal with. 

To optimize your email length, you need to make sure it communicates well without overloading information that overwhelms the recipients or confuses them. 

You need to think about these questions : 

  • How long your subject line needs to be in terms of your email overall length? 
  • How will your email subject line connect to the overall email boy and the first opening line of the email body? 
  • Is your Subject line length suitable for mobile users?
  • Will those images in your email body show up, or is it too big?

Tips For Writing Subject Lines In Right Way 

Well, there is no perfect line when it comes to the subject. So what works for others might not bring results to your brand. 

The world is changing, and so do the people, and your subject lines are required to adapt accordingly in order to rise above the busy and overloaded inbox. 

Here are some of the tried and true tips that you can use for writing your subject lines in the right way : 

tips for writing your email subject line

Welcome Ideas From Everyone 

The subject line is not the responsibility of one person; coming up with such powerful and impactful lines can be too much if you are depending on one person’s mind. 

So get your team involved in this, call out your people to brainstorm, and let the creative juice flow. 

The more ideas you have, the better your writing will be. So welcome everyone’s ideas, and the diversity will help. 

Avoid Using Fake FWD or RE 

When you are using the subject line, make sure it’s not misleading or fake, and also avoid tricking the subscribers. 

It includes not using RE or FWD, as it looks like your email is forwarding or replying to some important email. 

This can make your email end up in a spam folder, so don’t use deceptive tactics; it can make you look like you are taking advantage by mixing personal relationships and transaction emails. 

Don’t mislead the audience by using an open-bait subject line. This is considered against the CAN-SPAM act. 

Add Humor For Your Audience 

Even though your brand is considered serious, you can try adding humor now and then. 

So this is always effective since laughter is the best medicine and reduces pain, and syncs the brain of the writer and reader, making them emotionally attuned. 

Depending on the brand and campaign, you can consider using rhymes, humor, puns, or alternation. Adding a bit of fun can help the levity of your email and make it stand out. 

Consider Some Emails Are Destined For Low Opens 

You want to have high open rates in every email of yours. However, there are some emails that are destined to have low open rates, 

So don’t focus on open as the main KPI for your subject line success, especially when it’s related to transactional email. 

Go Beyond Your Subject Line 

The subject line is not just living in a vacuum; the subject line, sender name, preview text, and everything go hand in hand. 

So you can consider preview text as the extension of your subject line. 

When you are crafting the subject line, take consideration of preview as it can help. You can work with both of them, and it will make sense when it gets read together. 

Also, avoid repeating the sender’s name in your subject or preview text. 

When you are writing your subject line, consider it as one part of the ‘envelope’ of your email. 

The goal here is to get the recipient to open the email, and here using preview text and adding the sender name can help. 

Be Choosy When To Use Urgency 

No matter what emails you are sending, it should be smart to use urgency but sparingly. 

Subject lines that have urgency give you a 22% higher open rate, but if you are using it too much, this will end up losing its effects. 

It causes fatigue in subscribing by overusing the same thing. So creating a sense of FOMO can be a good way to get more open, but when you are overusing it and adding it to every single email, it makes your subscriber feel numb. 

Don’t Get Too Focus On Length 

One of the important aspects of writing an email subject line is understanding how long it can go. 

When you are thinking about facts and recommended characters, it’s around 45 to 60.

The reason is the subject line might stand out to be different from its standard, so here you might pick an extremely short subject line; it can be one word or quite long. 

However, you can write long subject lines, but the tool won’t let you add more because of limitations, and it will look different in the recipient’s inbox/ 

Here you either go short or write really long. Since there are no hard and fast rules, you can test writing at different lengths. 

So the overall point is not getting too much focused on the character counts. 

Focus On The Subscribers 

Start using ‘ you in your subject line more, this adds more personalization, and as a marketer, it’s your job to make it easy for others to say yes, and this will do that. 

Here is how it works : 

  • Subject lines are mostly written with the brand as the subject; it’s more focused on brands instead of subscribers.
  • Subscribers require to know why they should open emails, and if it’s not something directly related to them, why would they even care? 
  • It’s a mental shift that helps in starting to write copy; it centers the subscribers as a subject instead of the business or you. 

Add The Practical Proof 

Using ‘I’ can also work as its social proof, which does wonders. You require to look for what your audience wants. Do they want to promise the results, or does it include the outcome in the subject line? 

Would they see someone else did it, for example, if you can add the case study as proof in the subject line? 

You can try testing by using lines like : 

  • You will get ( add the results they want ) with this ( add the tactics that will be used)
  • I got ( add results they want) with ( add tactics you used)

A small change can make huge differences and create different meanings. So depending on what your audience wants, you can try both of the ways in your subject line. 

Use Different Subject Line For Transactional Email 

There are some lines you should never consider touching about; it mostly includes transactional where your customers are very specific. 

Think about the subject line strategy for marketing email or broadcast vs. the transaction subject lines differently. 

They both have different goals and might be managed by different teams. 

For example, password reset emails do not require a creative subject line; instead of this, it needs clarity and simplicity. 

Personalize Your Email Subject Line 

There is no doubt that personalization is a need in today’s market. It applies the same to the email subject line. 

According to Data by Yes Lifecycle Marketing, there is a 50% increase in open rates when you do personalization. 

However, there are different ways that you can use it, including : 

  • You can start with name personalization, it can help you in improving the open rates, but this one can decrease the click-to-open rates or CTOR.
  • This is called the magpie effect, where something makes your subscriber feel drawn to open, but they don’t have any real intentions behind their action. 
  • Using the first name in a re-engagement email generates a much higher open rate, but it might lower your conversion rate.
  • Don’t personalize because of this; make sure it’s aligning with your goals and strategy in order to maximize effectiveness. 

Be Caution When You Are Using Emojis

If a picture is worth more than using a thousand words, it can help in eliminating the characters, so using emojis where it suits makes sense. 

  • Emojis are powerful; they can help in standing out your email in the recipient’s inbox.
  • However, use them to make sure of accessibility. 
  • Make sure that your subject line makes sense if you are reading it aloud with or without emojis. 
  • Also, think about how a screen reader or voice assistant will read it.

Avoid Being Too Vague 

It’s important that you are being specific in your subject line instead of vague. 

Using the vague subject line is risky; the people who want the content might ignore the email, thinking it’s not for them.

Keep Your Reader Feel Curious 

Curiosity is considered one of the strongest incentives humans have, and using an effective and good subject line can make your reader feel curious. 

For example, sending an engagement email from Linkedin usually includes : ( name) just commented on your post. 

Here it creates a curiosity gap, it’s a void in the knowledge that will be filled only if you click on the email and read it. 

So work on creating a curiosity gap with your subject line and see how it will increase the open rates. 

With your email subject line, focus on resting a sense of intrigue by posting questions and keeping answers in the email. 

Add Action To Your Email Subject Line 

When you are writing an email’s subject line, make sure you are adding action. It will help in making it more clear and give ideas to subscribers regarding what you want them to do. 

You are sending marketing emails to your contact to take action, and that’s why you add CTA or call to action, so use it on your subject line.

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