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Email Marketing

How to Write Email Subject Lines to Boost Open Rates [Examples]

by Kazimierz Rajnerowicz·Updated
Best email subject lines cover art

Let’s make it clear—

Email subject lines are the most often neglected element that can make or break a campaign.

And the last thing you want is to ruin all the effort you put in building your contact list and designing emails by overlooking a single line of text.

Luckily, you’re right where you need to be!

In this article, you’ll learn:

  • Some of the best email subject lines for sales and better engagement
  • How to write effective and catchy subject lines
  • What things to avoid in your subject lines

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If you’re looking for other info on making the most of your emailing efforts, check out:

Follow Tried and Tested Email Subject Line Formulas and Best Practices

Here are some of the most powerful email subject line templates. Replace the Xs with something suitable for your business and you are good to go.

  • {Holiday/Summer/Christmas/Black Friday} Sale. Up to {X%} off
  • {X} is here!
  • Your new favorite {X}
  • Let’s talk about {X}
  • Up your {X} game
  • New {X} on the block!
  • {X} things you didn’t know about {X}
  • This {X} is mind-blowing
  • Get your free {X}
  • Excited for {X}?
  • Looking for {X}?
  • A better way to {do X}
  • {Name}, we’ve picked this {X} for your
  • {X}? We’re on it
  • Can we get your {X} started?
  • Need a last-minute {X}?
  • You asked for {X}, you got it
  • Introducing the new {X}
  • Get your {X} fixed 

Our Favorite Email Marketing Subject Line

There is one foolproof email subject line hack. The formula is very powerful. One subject line to rule them all.

Are you ready?

Here’s the best subject line for open rates that will blow your mind.

Email subject line template

This subject line doesn’t play around. We have all that we need. In several words, we establish that:

  1. We’ll be quick = we won’t waste too much of the recipient’s time
  2. We know something about the recipient = it makes the email more relatable
  3. We ask for a favor but we don’t mention any money/discounts =  it’s not too salesy

Being straightforward and keeping things simple is the golden rule of email marketing. That’s why this line is so effective.

An example of an effective email subject line

To use it correctly, you need to send it to the right customer segment. You can learn more about tracking your customers here: eCommerce Customer Segmentation Strategies

Email Subject Line Best Practices

About 34% of recipients open emails based on their subject lines. It is the second most important factor, right after the sender’s name. You should pay special care to this part. After all, what is the point of writing an amazing email that nobody will read because of a lame subject line?

Email open rates statistics

Before we take a look at real email subject line examples, there is one thing that you should realize.

You may think that including words like “now” or “last chance” will improve your subject lines. But there are no magic words that will increase open rates by themselves. Creating a sense of urgency, for example, is what matters—the choice of words is secondary.

Email Subject Lines With High Open Rates

Best email subject lines for sales:

  • Ask for a favor
  • Appeal to authority
  • Recognize actions
  • Make recipients curious
  • Use emojis
  • Appeal to needs and dreams
  • Use numbers
  • Are funny
  • Shock and provoke
  • Offer freebies and discounts
  • Start a story
  • Ask questions
  • Create a sense of urgency

In the sections below, we’ll be taking a closer look at each one of them.

Use Your Email Subject Lines to Ask for a Favor

This technique is best for writing email subject lines that increase engagement 

When you start running away from a dog, it will chase you. Barking. But as soon as you turn the situation around and start chasing the dog, it will run away in terror. To be on the safe side, you may want to try it out on a Chihuahua, not on a Rottweiler. But it is true. 

A similar mechanism applies to sales. An instinct kicks in. If your customers perceive you as a salesman, you are a threat and they will run away. But as soon as you put yourself in a more vulnerable position and ask for their help, they will be happy to assist you.

Asking For a Favor Email Subject Line—Examples

Examples of email subject lines that ask recipients to do something

Once you start asking for something else than money, your open rates will go through the roof. 

There are more benefits. When you ask your customers for help, you get valuable feedback and build better customer relationships.

What is the ideal length of a subject line?

You should try to keep them as short as possible. According to research, email subject lines that use between 6–10 words have the highest open rates. Additionally, you should use between 40–50 characters. If you want to cover all mobile devices too, cut it down to less than 30 characters.

Draw Attention With Big Names and Expert Opinions

This technique is best for writing email subject lines that promote your content

A movie may be a total stinker but if the cast is good, people will watch it still. We are attracted to celebrities, experts, and all kinds of figures of authority. A testimonial from a recognizable brand or figure can do a world of good for any business.

Every niche has its own superstars.  If a name is recognizable, your customers will click it. Sometimes you can add some more details and it will start to ring a bell. I hadn’t heard of Caroline Hynes before opening the email but I do know Zendesk.

Appeal to Authority—Subject Line Examples

Examples of expert subject lines

There is an easy hack that sometimes works but it is slightly overused. You don’t have to involve famous people in your business to mention them in your email subject lines. Check out this line:

Do you want to become the next Elon Musk?

Well, who wouldn’t? But it’s a figurative Elon Musk, not the real one. Which makes this line OK-ish. After all, we don’t mean becoming a clone of Elon but rather becoming smart, rich, and successful. Email lines like this one allow you to bend the rules. But you should still be careful about legal aspects and trademark laws.

A/B Testing Email Subject Lines
If you can’t decide whether to go for a funny subject line or a “professional” subject line, send both. With email marketing software, it is simple as ABC. Or even simpler, because you don’t need the C for email subject line A/B tests. You can send marketing emails with two versions of the subject line and compare their open rates.

Pay Compliments to Your Customers and Recognize Their Actions

This technique is best for onboarding and thank you email subject lines

You don’t need to toady up to your email recipients but saying something nice from time to time may work. It is also important to give positive feedback when customers do something the right way.

Try to keep it simple. A general remark that fits a given context is better than elaborate canned flattery.

Examples of Email Subject Lines That Butter Customers Up

Examples of subject lines that pay compliments

You should always acknowledge the most important actions taken by your customers. It’s a good opportunity to hint at some next steps. Send welcome emails when they sign up. Congratulate them on completing their purchase. Tell them how awesome they are.

There are many ways to strengthen your customer relationship and marketing strategy. Thank you, welcome, and follow-up emails are just some of the popular hacks. Learn more here: Relationship Marketing Ideas & Examples

Stir up Curiosity With Marketing Email Subject Lines 

This technique is best for informational email subject lines and promoting new content

Sometimes a good subject line can be vague and mysterious. You don’t have to reveal your cards all at once. Give your recipients some hints. But make sure that they won’t get the full picture without clicking.

Intriguing Email Subject Line Examples

Examples of email subject lines that stir curiosity

It’s all about making customers feel special. A member of a secret club. You can say something like:

Hey, here’s an exclusive sneak peek. 


Hey, I have a secret to share but promise not to tell anyone. 

Something along these lines always works.

Your email lines should convince customers that something exciting is coming their way. It’s so awesome that you can’t wait to share it. Even if it is yet another discount.

Add Some Spark to Your Subject Lines With Emojis

This technique can add some additional spark to funny email subject lines

Emojis are like 50 Shades of Grey or Twilight books—”everybody” hates them but they sell like hotcakes. Or at least marketers used to believe that they do. Now there is no consensus about their effectiveness.

In some industries, however, they increase open and click-through rates. So, do they work or not? The short answer is “it depends” and you have to try it out. It shouldn’t hurt your business and can boost user engagement.

Subject Lines With Emojis—Good Examples

Emojis in email subject lines

Sometimes you can use emojis in creative ways that help you pique your readers’ interest. The We can be the Yin to your Yang (so cheesy…🐀) subject line wouldn’t be the same without the rat emoji. It is also a fragment of a larger puzzle—a reference to 2020 being the Chinese year of the rat.

Emojis can make your emails look less serious. It can be a good thing! Humor is a powerful ally of marketers. Check out how to write funny welcome messages for new customers.

Activate Hidden Dreams With Best Email Subject Lines

This technique can be applied to write effective email subject lines for eCommerce

What is one of the best messages that your email lines can convey? That you can help your customers with achieving whatever they want.

To quote Blair Warren, the author of The One Sentence Persuasion Course, “people will do anything for those who encourage their dreams.” Tune into your customers’ aspirations and dreams to increase their engagement.

Marketing Subject Lines That Root for Your Customers

Good examples of email subject lines that call to action

You must be like a good coach who gets them pumped up and ready for action. Ultimately, all products and services are meant to help customers achieve their goals. But a call to action that focuses on activities is better than ones that focus on things.

Improve Subject Lines by Adding Numbers

This technique is suitable for newsletter subject lines

Numbers always add more substance to whatever you are trying to say. In spite of the fact that more than 142% of statistics are made up.

Got you there for a second, right?

You definitely shouldn’t invent numbers. But there are many good ways to incorporate them into your email subject lines. For example, they help to clarify that something is a list, how long something will take, or how big is your discount.

Email Subject Lines With Numbers—Examples

Good email subject lines that use numbers

9 ways to improve your email open rate sounds better than Different ways to improve your email open rate. The number makes it tangible and the reader will know that there is a list. And lists are easy to skim, so they are perfect when someone reads online.

You can also try to leverage the power of social proof. Subject lines that use numbers and appeal to popularity enjoy high open rates. Something like “Check out how 10,000 users improved their SEO overnight” can work. But be careful—round numbers sound spammy.

Sneak a Joke Into Your Marketing Email Subject Lines

A good sense of humor can be an asset when it comes to writing catchy email subject lines for sales

Slip on a banana peel and the world is at your feet. The world of marketing is no different. Your customers will open any marketing email if the subject line will make them crack a smile.

Comedy is difficult to write because it relies on unusual connections. You need to get creative but, at the same time, rely on your recipients’ knowledge. A funny line is funny only if you get the joke.

Examples of Funny Email Subject Lines

Funny subject lines

Email subject lines should be short and snappy. Because there is no place for buildup, marketers usually rely on puns. Or recognizable references with a humorous twist.

If something is random and unexpected it will usually be funny. Like raindrops on roses and whiskers on kittens which you can create with a 3D editor. It sounds cute and funny even if you don’t know the song.

Tip: Resorting to humor only works if you know your audience really well. You should also avoid jokes that may be offensive or controversial. “Funny” email subject lines that make half of your customers laugh and half of them angry are no good. It can really harm your business.

Use Shocking Email Subject Lines to Provoke Your Recipients

This technique is suitable for catchy newsletter titles

Mentioning controversial subjects will help to draw attention to your emails. The same goes for bold statements or outrageous theories.

The oldest trick in the book is to imply that the old way of doing something doesn’t work. Or that a well-established agreement is incorrect. If you say that the earth is flat, you can get enough attention from people correcting/defending you to turn it into a career. If that’s still not enough, mention sex.

Clickbait Email Subject Line Examples

Shocking email subject line examples

You have to be careful. Your assertions should sound like legitimate questions or inspiring stories that just happen to be unusual.

Watch out!

There’s a huge difference between a tasteful provocation and being scandalous. What works for a celebrity gossip rag does not have to help your business. If you overdo it, you can get many negative reactions and your reputation will go down the drain. Mentioning sex, religion, and politics can backfire really badly.

Reveal Discounts and Freebies in Your Email Subject Lines

This technique is essential for writing effective email subject lines for sales

Someone said that the best things in life are free. That’s somewhat debatable. But everyone surely would agree that free things are the best. 

If you are offering something for free, mention it as soon as possible. Emails that announce free gifts have a much higher open rate. Obviously, if they announce it in the subject line.

FOMO Subject Line Examples

Email subject lines that use the fear of missing out

Discounts are also great but they are a more difficult case. The main problem with discount emails is that it’s the most overused type. It’s really difficult to stand out. Especially, if your products are always on a discount. 

Imagine subscribing to 20+ companies that announce a new discount every week. It would turn your inbox into a mess and make you immune to all special deals. Even if they were really good deals!

Are you looking for more subtle and effective ways to give discounts? You may be interested in trying out a discount chatbot template available in Tidio.

Try Out Email Subject Lines That Promise a Good Story

Hinting at a good story is often used in professional email subject lines in marketing campaigns

Grab yourself some popcorn.

Do you have it? 

It was a dark and stormy night. I was trying to come up with the best email marketing subject line in history. While I nodded, nearly napping, suddenly there came a tapping…

Wait, what? Is this a story or a poem?

Anyways, you probably keep wondering what happened next. Storytelling is an important part of marketing. Great subject lines can get you hooked and curious. The rule of setup and payoff applies to subject lines and emails too. Check out some examples.

Subject Lines That Read Like Opening Lines of a Good Story

Examples of email subject lines that use storytelling techniques

The subject line from Harley-Davidson feels very natural. The mode of transport seems to be incidental yet linked with a very particular lifestyle. Telling a real story of a band that tours on motorcycles is way cooler than saying “buy our bikes.”

Use Subject Lines to Ask Questions and Strike a Chord With Customers

This technique is best for personal email subject lines.

Have you ever wished you had more money? Or were more attractive?

You have? No way! Me too. I guess that makes us buddies.

What’s the next thing you’re gonna tell me? That you sometimes feel sad or happy?

Ok, let’s stop. Have you noticed what I did just there?

You have? Amazing. We’re on the same wavelength. 

As you can see, asking questions is a really powerful way of making an immediate connection. Here are some great examples of question-based email subject lines.

Questions in Email Subject Lines—Examples

Subject lines that ask questions

Questions can be a hit or miss. If the answer to them is negative, then nobody is going to open your email. But what if you knew your audience and sent targeted email campaigns to thousands of users? Some of them are bound to be a perfect match.

Create a Sense of Urgency and Scarcity

This technique is best for writing email subject lines for sales

There are some things that can be taken care of anytime. And if you can do something any time, it usually never happens. After all, there is no rush.

But if you add a ticking clock, suddenly it becomes a whole new situation. Fear of missing out on a good deal is a powerful ally of email marketers too.

Last Chance Subject Line Examples

Good examples of exciting email subject lines

 “Last chance” offers are among the most popular types of marketing emails. They are also overused. If you check your email inbox, you’ll discover that “last” turns out to be a very flexible and relative term.

Avoid These Things in Your Marketing Email Subject Lines

Following one of the tricks mentioned above should increase your open rates. There are some more things you should remember when writing your subject lines.

An infographic showing common subject line mistakes
  • Don’t use ALL CAPS and multiple exclamation marks!!!
  • Don’t add RE: or FW: to trick recipients into opening your emails
  • Don’t use too many emojis
  • Don’t send multiple emails with the same subject lines
  • Don’t make your subject lines too long (50-60 characters max)

Sticking to these rules will keep your emails safe. And they won’t land in the email spam folder.

An infographic about the connection between email subject lines and SPAM

About 69% of emails are reported as spam based on their subject lines alone.

Here are some spam-triggering words that you should always avoid in professional email subject lines:

  • 100%
  • #1
  • As seen on
  • Cash
  • Click below
  • Click here
  • Credit
  • Double your income
  • Earn
  • Earn $
  • Free investment
  • Freedom
  • Get paid
  • Join millions
  • Lose weight
  • Lottery
  • No experience
  • Order today
  • Prize
  • Risk-free
  • Won
  • You are a winner!
  • You’ve been selected!

Read more: How to Avoid Spam Filters When Sending Emails

Key Takeaway

If you are trying to sell something, chances are that your email open rates will be much lower. With an average open rate of 15.7%, eCommerce is at a significant disadvantage.

Writing great marketing email subject lines can increase your open rates from 10-20% to 40–50%. It means that you can double or even triple the number of engaged customers. When you send your campaigns to thousands of people, this can correspond to hundreds of sales.

If you want to make your subject lines better, remember that:

  • There are no “secret words” that will work better than good, personalized email subject lines
  • You can try out formulas but remember that they are effective because they use specific advertising appeals
  • Some of the best appeals are linked with creating a sense of urgency, solving a problem, or focusing on benefits
  • You can use numbers, emojis, and storytelling techniques to increase your open rates
  • People read emails that make them laugh, shock them, or challenge their beliefs
  • Offering discounts and freebies is overused but effective if you reach customers at the right moment
  • Avoid all caps, exclamation points, and long sentences in your subject lines

If you want to send and monitor your email campaigns, try out Tidio. You’ll be able to track the performance of different email subject lines and find the best ones.

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Kazimierz Rajnerowicz
Kazimierz Rajnerowicz

Kazimierz was one of the original authors of Tidio Blog. His primary objective was to deliver high-quality content that was actionable and fun to read. His interests revolved around AI technology and chatbot development.

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