September 9, 2021

From Zero to Inbox Hero: 9 Email Subject Line Best Practices

In this post you'll learn:

Struggling to get the email open rates you want? Use these email subject line best practices to engage your subscribers and generate more click-throughs.

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Your subject line is the gateway to your email. If it’s a flop, recipients simply won’t click through, making the rest of your email completely redundant. You might have written the best email in the world, but if the subject line lets it down, nobody’s going to see it.  Avoid your email body gathering dust by ensuring your subject lines do the job they’re supposed to - catch attention and encourage action. 

Step into the spotlight: subject line styles and examples that stand out

Email subject lines come in all shapes and sizes. The style you choose will completely depend on the type of email you’re sending, your target audience, and what you want to achieve with the email.  Promoting a sale on your latest product line? You’ll want to get straight to the point instead of using a cryptic subject line that doesn’t tell recipients what they’ll find once they open your email.  Introducing your services to a potential client? You want to stand out in their inbox with a short and sweet subject line.  So what kind of subject lines are out there in the wild? 

1. FOMO, scarcity, and urgency 

Injecting a good old-fashioned sense of urgency into your subject lines can make readers take action: 

  • FOMO (the Fear of Missing Out): nobody wants to feel like they’re last to show up to the party and they’ll take action if it feels like they’re missing out 
  • Scarcity: use your subject line to hint that there are only a few spaces or products left or that you only have a limited number of something available
  • Urgency: people who feel like they’re running out of time will take action. Hint that there are only a few hours left to grab a deal in your subject line 

2. Personal

Who doesn’t like to hear (or read) their own name? Personalizing your subject lines makes your emails stand out in inboxes and creates an unconscious connection with recipients, making your emails 22% more likely to be opened. As well as using a recipient’s first name, you can also include other personal information that you have on them, like a recent event they attended or their last purchase. 

"New lines in swine added to our Piggin' Sale, Dave!"

3. Question 

Questions invoke curiosity. The more relevant the question is, the more likely a recipient is to click through to find out the answer. Adding a question to your subject line not only gives readers a peek into what’s inside but can also open up a dialogue. 

"Are you ready for the weekend?"

4. Lists and numbers

Numbers stand out in an inbox full of words. Using numbers in percentages or in the form of a list in your subject line can encourage readers to click through, especially if it provides an insight into exactly what they’ll get on the other side. 

"15% Off Everything In Our Summer Sale"

5. Action

Using powerful action words in your subject lines can stop readers in their tracks. It leaves no question about what you’re asking them to do and encourages them to, well, take action.

"Sign up for Dreamforce now. Your front-row seat awaits."

Enhance open rates with these good email subject line examples 

You probably have email marketing campaigns for a number of different occasions, such as product promotions, weekly newsletters, outreach emails, product recommendations, and as part of your content marketing strategy. Each of these different types of emails requires a different type of subject line to entice email recipients to click through. We’ve rounded up a selection of great email subject line examples to inspire your next email. 

7 powerful email subject lines for introduction and outreach 

This email promises to be quick (time is precious!) and mentions a personal bit of information about the recipient. 

"A quick hello (and congrats on the move!)"

Mentioning a common interest or a mutual acquaintance is a great way to gain the trust of a recipient who doesn’t yet know who you are.

"Reaching out to you via Cora Browne"

Calling out a commonality instantly creates a connection. We’re more likely to respond to people we have met in person or have some kind of connection with beforehand. 

"Great to meet you at Dreamforce last week"

Combining past achievements with what you want to gain from the email is a great way to get the attention of the recipient. 

"Published in Moz 3x. Want to write for Base2Digital"

It’s short and it’s sweet, but who wouldn’t want to find out what the question is? 


Show that you’re going to tackle any objections a customer or client might have in your email subject line. 

"Overcome what's holding you back"

Asking a question piques interest. The encouragement to then respond to the email makes this subject line actionable. 

"Ever had this problem? Tell me about it."

8 effective email subject lines for newsletters and promoting new content 

This newsletter subject line starts with an emoji to attract reader attention. It then hints at a list and uses a heavily emotive word (“horribly”) to entice a click-through. 

"✋ 5 Horribly Under-Utilised b2b Channels"

Using second-person pronouns automatically involves the reader in your email. Accompanied with the emoji smiley face, this subject line feels very human and connective. 

"Your weekly Instagram posts sorted 😃"

This subject line is both personalized with the recipient’s name and asks a question at the same time. It’s a double whammy in piquing curiosity - who doesn’t want to find out if they’re funny? 

"Are you being funny, Dave?"

Numbers (especially numbers this big) make subject lines specific. Adding in a time frame makes clicking through into this email a no-brainer. 

"How I Got 26,778 Subscribers In 13 Months"

Using a powerful quote as a subject line evokes emotion in the recipient and drives click-throughs. 

"I could buy a car with this marketing gig"

This subject line is very specific with its offering and gives readers a good insight into what they’ll get when they open the email. 

"Discover new opportunities with unique e-commerce keyword data in your pocket"

Short and simple, but very sweet. This subject line leaves absolutely no confusion and provides a local appeal that will pique the interest of anyone living in or visiting Brighton. 

"Discover Brighton's outdoor restaurants"

“How to” headlines are a go-to for actionable blog posts, and they work just as well as email subject lines. 

"How to build for the future of events"

6 persuasive email subject lines for product promotion and recommendations 

This subject line uses an emoji and second-person pronouns to capture the reader’s attention. 

"🏖 Staycations Are Calling Your Name!"

Using the word “we” makes readers feel like they’re part of something. The added emoji ensures this email subject line stands out. 

"Summer, we're not done with you yet 🌞"

Asking a question hooks the reader, and the second-person pronoun again makes the recipient feel valued and understood. 

"Ready for a few finds that are all about you?"

The combination of sunshine emojis and the use of a number makes this subject line a compelling click. 

"🌞 Our 15% Summer Sale Starts Today 🌞"

Again, this subject line uses an emoji to stand out in a text-based inbox. It creates a personal connection by acting as a friendly “reminder” for readers to claim their vouchers. 

"Don't forget your 20% voucher! ☝"

The all caps “important” draws reader attention to this subject line, and the punny phrasing showcases the brand’s personality. 

"IMPORTANT: Dave, get these deals on squeals in time for the Bank Holiday! 🏖"

9 must-do email subject line best practices 

1. Be descriptive

Punny and clever subject lines may seem like a fun idea, but they often leave recipients feeling confused. If you want someone to open your email, be specific and describe what they’ll get when they open it. The last thing you want is to disappoint readers who don’t get what they were hoping for when they click into your email. 

2. Short, but not too short

Research shows that the shorter the subject line, the better - but not too short. In fact, subject lines with between six and eleven words perform the best, with an average open rate of 21%. Be mindful of how your subject line will appear on mobile devices too, as email providers often cut them down to fit on the screen. 

3. Don’t replace words with emojis

Emojis help your subject line stand out in a sea of text but don’t go replacing every word in your subject line with an emoji. Use them sparingly, and only to complement your words so you still get your message across. 

4. Use capitalization sparingly

Capital letters are often associated with yelling, so limit your use of them in subject lines. In one of the examples above, the brand capitalizes the word “important”, but the rest of the subject line is in lower case - this is the way it should be. 

5. Write many before choosing one

The first subject line you come up with won’t always be the best. Instead, write at least 10 potential subject lines to see what ideas you spark from previous iterations. The more you write, the more you’ll start to let loose and let the creative juices flow. 

6. Understand your email subscribers

This is rule 101 in email marketing, but it goes without saying that you should know who you’re targeting and what they expect from you. Email segmentation will help you cater to each of your audiences - for example, if you’re targeting Boomers, don’t use trendy language that they won’t understand. Likewise, if you’re targeting Gen Z with a fun new beauty range, use language that they can relate to.

7. Use second-person pronouns

Include the reader in your email by using second-person pronouns like “you” and “your”. This makes them feel a part of something and like you’re speaking directly to them. 

8. Sprinkle in emotive words

Emotive words pack a punch with readers. They invoke a feeling in recipients, whether it’s joy, surprise, happiness, or something else. Try using some of these emotional trigger words to spark curiosity and intrigue in recipients. 

9. Get some help 

Jarvis’ email subject line template provides inspiration for your emails. Simply plug in what your email is about and choose a tone of voice you want to use and the AI technology will come up with a selection of subject lines you can use (or tweak to better suit your needs). And, if you want to write subject lines up to 2x faster, engage Jarvis’ boss mode

Jarvis email subject line template
Jarvis Email Subject Lines Template

Your swipe file: email subject line formulas you can use right away

So, you’re ready to write a great subject line, but staring at a blank page isn’t helping you get your groove on. Don’t worry, we’ve got you covered. Here are some formulas you can tweak to match the content of your email.

Introduction email subject line formulas:

  • Great to meet you at [event] last week!
  • Do you need a [service you offer]? 
  • I was given your email by [mutual acquaintance] - would love to connect! 
  • A quick hello (and [personal anecdote]!) 

Welcome email subject line formulas: 

  • Welcome to the [brand] family, [name]!
  • Congrats on being the newest member of [brand’s] club
  • Wow! Welcome to [brand]
  • Welcome to the party! How can [brand] help you? 

Promotional email subject line formulas:

  • Today only! [Your limited time offer goes here]
  • Claim your [deal] right now to save [X amount]
  • Time is running out! Get [deal] before it goes 
  • [deal] starts today! Are you in? 
  • Save [X%] on [promotional product]

Newsletter email subject line formulas: 

  • How to X and get Y 
  • What is your X, [name]?
  • Are you ready to X, [name]?
  • What we learned from doing X 
  • 6 important steps to X so that you can Y 

Product recommendation email subject line formulas: 

  • Warning: this email contains [product] ideas you’ll love
  • Why you need a [product] in your life 
  • Looking for a [product]? Look no further 
  • Our new [product] is flying off the shelves 
  • We’ve picked these products especially for you 

How to test email subject lines for best results 

It takes a while to get the formula right for a successful email subject line. Chances are, you won’t get it perfect right away, and that’s okay. As long as you test what’s working and what isn’t, you can optimize your subject lines until the click-through rates just keep on going up. The main metrics you want to track are open rates, as this shows how compelling your subject lines are. 

The easiest way to determine how well your email subject lines are doing is to A/B test them. 

A/B testing involves sending one subject line to half of your email list and a different subject line to the other half. You can see which subject line has the highest email open rates and which one has the most click-throughs to determine which one is a success. Make a note of the differences between each subject line and why you think the best-performing one was most successful. 

Remember marketers, your email subject lines are the gateway to your emails. Overlook them, and you’ll struggle to get higher open rates. But, spend time crafting curiosity piquing, engaging subject lines and you’ll find that more people open your emails which leads to more click-throughs and more sales. Make use of marketing automation to test your subject lines and improve your existing ones for better results. 

Sign up for Jarvis and start creating effective email subject lines that drive results.


Meet the author

Dave Rogenmoser
CEO of Jarvis

Dave is the Co-Founder Jarvis and Proof, a Y Combinator-backed tech company base in Austin, Texas. He is also a husband and father of 3 boys. You may be surprised to hear Dave once ate the beating heart of a King cobra & is 6'8" tall.

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