According to statistics, emails have the highest return on investment. For every $1 spent on email marketing, there is a return of $32. Over the years email marketing has been a favorite among marketers because it is easy to plan, implement and improvise.

The best way to write email subject lines for higher opens (instead of being marked as spam) is by leveraging natural human tendencies and psychological principles.

Email subject line is as important as the email body content. Now that you know about the importance of that ‘one line’ that has the potential to grab the attention of the email and urge them to open your email, let us take a look at some of the best examples from the industry.

Steps for Writing Good Subject Lines

Here are some of the factors which contribute towards a good subject line.

Curiosity: Curiosity is something which works wonders. Add text or content which will invoke interest in the reader’s mind. However, do not be too obscure that the email gets reported as spam.

Urgency: Using urgency is a classic approach and generally works because it compels the reader to take immediate action or at least gives the feeling that something is of utmost urgency. However, there are more subtle ways to express urgency and that is how it should be.

Relevance: One of the most important thing for subscribers is to receive timely and trendy information. This needs to be leveraged while designing subject lines as well. Trendy topics or trendy headlines should be used in subject lines to keep your readers interested.

Personalization: Personalization always works because different people have different preferences. Personalization gives a feeling of importance and is liked by subscribers. It is one of the best strategies in Content Marketing that not only helps to retain good relationships but also in lead generation.

What is Open Rate?

Email open rate is the percentage of the total number of subscribers who have opened an email campaign. These rates depend on various factors including the subject line, relevancy for subscribers, personalization, content etc. However, a value in 20-40% range can be considered as a healthy open rate. There are various factors which impact open rates and Subject Line is one of them.

Here are top examples of the best subject lines for email marketing, and the proven principles that make them work…

Fear of Missing Out

One psychological principle that is practically impossible to resist is the fear of missing out. You can use this fear in your subject lines by adding an element of scarcity (limited availability) or urgency (limited time).

In fact, subject lines that include words that imply time sensitivity–like “urgent”, “breaking”, “important” or “alert”–are proven to increase email open rates.

Here are some great sample subject lines for emails that use the fear of missing out

  1. Warby Parker: “Uh-oh, your prescription is expiring”
  2. JetBlue: “You’re missing out on points.”
  3. Digital Marketer: “[URGENT] You’ve got ONE DAY to watch this…”
  4. Digital Marketer: “Your 7-figure plan goes bye-bye at midnight…”
  5. Digital Marketer: “[WEEKEND ONLY] Get this NOW before it’s gone…”
  6. Jersey Mike’s Subs: “Mary, Earn double points today only”
  7. Guess: “Tonight only: A denim lover’s dream”

Curiosity

Humans have a natural desire for closure– we don’t like having gaps in our knowledge. You can leverage this desire for closure by leaving your subject line open-ended so subscribers will be curious, like a cliffhanger that can only be satisfied by opening the email.

You can make subscribers curious by asking a question (and answering it in your email), promising something interesting (like pictures or a surprise gift), or simply saying something that sounds strange or unusual.

Here are some great examples of curiosity inducing subject lines

  1. Manicube: “*Don’t Open This Email*”
  2. Grubhub: “Last Day To See What This Mystery Email Is All About”
  3. Refinery29: “10 bizarre money habits making Millennials richer”
  4. Digital Marketer: “Check out my new “man cave” [PICS]”
  5. Digital Marketer: “Is this the hottest career in marketing?”
  6. Thrillist: “What They Eat In Prison”
  7. Eat This Not That: “9 Disgusting Facts about Thanksgiving”
  8. Chubbies: “Hologram Shorts?!”
  9. The Hustle: “A faster donkey”
  10. Mary Fernandez: “? a surprise gift for you! {unwrap}”

Funny Subject Lines

If your subject line makes your subscribers laugh, then they’ll simply have to open it. After all, have you ever read a subject line that tickled your funny bone and you didn’t read it?

Being humorous requires a bit more thought and creativity, but it can really pay off in terms of your open rates.

Here are some funny email subject lines to make your subscribers laugh…

  1. Eater Boston: “Where to Drink Beer Right Now” (Sent at 6:45am on a Wednesday.)
  2. OpenTable: “Licking your phone never tasted so good”
  3. Groupon: “Deals That Make Us Proud (Unlike Our Nephew, Steve)”
  4. The Muse: “We Like Being Used”
  5. Warby Parker: “Pairs nicely with spreadsheets”
  6. UncommonGoods: “As You Wish” (This is a reference to the movie The Princess Bride.)
  7. Travelocity: “Need a day at the beach? Just scratch n’ sniff your way to paradise…”
  8. TicTail: “Boom shakalak! Let’s get started.”
  9. Thrillist: “Try To Avoid These 27 People On New Year’s Eve”
  10. Baby Bump: “Yes, I’m Pregnant. You Can Stop Staring At My Belly Now.”
  11. Gozengo: “NEW! Vacation on Mars”
  12. The Hustle: “Look what you did, you little jerk…” (This one is a hybrid curiosity/humor email. Here’s what it says when you open it.)

Vanity

Everyone has a bit of vanity. People love to be liked, accepted and even revered by others… it’s just a part of being human.

That’s why some of the most clever subject lines use vanity to get you to open the email. To do this, you can either promise something that makes the subscriber look better to their peers, or invoke the fear of being shamed.

Here are some great examples of clever email subject lines that leverage vanity

  1. Guess: “Don’t wear last year’s styles.”
  2. Fabletics: “Your Butt Will Look Great in These Workout Pants”
  3. Jeremy Gitomer: “How Have You Progressed Since the Third Grade?”
  4. Rapha: “Gift inspiration for the discerning cyclist”
  5. La Mer: “Age-defying beauty tricks”
  6. Pop Physique: “Get Ready. Keep the Pie Off Your Thighs Returns.”
  7. Rapha: “As worn in the World Tour”
  8. Sephora: “Products the celebs are wearing”

Greed

You may not think of yourself as a “greedy” person, but it can be really tough to pass up a great deal… even if you don’t really need the item right now. That’s why sales, discounts and special offers work really well in your subject lines.

However, be careful about offering really huge discounts– the higher the percentage, the less reliable effect it has on your open rates (perhaps because consumers don’t believe large discounts are real).

Regardless, you can usually expect to see an increase in your click rates whenever you offer a discount in your subject line. That’s probably because the people who open these emails are already interested in your offer, so they’re naturally inclined to click.

Here are some great email subject line ideas for hitting your subscriber’s “greed” button

  1. Topshop: “Meet your new jeans”
  2. Topshop: “Get a head start on summer”
  3. HP: “Flash. Sale. Alert.”
  4. HP: “New must-haves for your office”
  5. Seafolly: “A new product you won’t pass on”
  6. Guess: “25% off your favorites”
  7. Rip Curl: “Two for two”
  8. La Mer: “A little luxury at a great price”
  9. Rapha: “Complimentary gift wrap on all purchases”
  10. The Black Tux: “Get priority access.”

Sloth

Another common trait among all humans is sloth, or the tendency to avoid work. Even people who aren’t inclined to be lazy would prefer a silver bullet over the long and hard route.

You can give subscribers an easier way to achieve their goals by offering a shortcut, or a useful resource that saves a lot of time and energy. (These useful emails are perfect for lead nurturing too!)

Here are some great examples of email subject lines that satisfy sloth

  1. “✔ 63-Point Checklist for Creating the Ultimate Optin Form”
  2. “Grow your email list 10X ⚡ faster with these 30 content upgrade ideas”
  3. “How to email a busy person (including a word-for-word script)”
  4. “Steal these email templates…”
  5. “A Native Ad in 60 Minutes or Less”
  6. “212 blog post ideas”

Pain Points

If you really understand your buyer persona, you should know their biggest pain points. Use those pain points to get subscribers to open your emails by solving that problem for them.

Here are some examples of email subject lines that bring out the subscriber’s pain points and offer a solution

  1. Pizza Hut: “Feed your guests without breaking the bank”
  2. IKEA: “Where do all these toys go?”
  3. IKEA: “Get more kitchen space with these easy fixes”
  4. HP: “Stop wasting money on ink”
  5. Sephora: “Your beauty issues, solved”
  6. Uber: “Since we can’t all win the lottery…”
  7. Thrillist: “How to Survive Your Next Overnight Flight”
  8. Guess: “Wanted: Cute and affordable fashions”
  9. Evernote: “Stop wasting time on mindless work”
  10. Duolingo: “Learn a language with only 5 minutes per day”

Retargeting

Retargeting emails are sent to subscribers when they fail to complete an action or a step in your sales funnel (e.g. when they abandon their cart, or fail to purchase after their free trial). These emails serve to bring your subscribers back to your sales process.

You can write effective retargeting subject lines by overcoming objections, offering something to sweeten the deal, or alerting them that something bad is going to happen if they don’t take action.

Here are some excellent examples of retargeting email subject lines

  1. “How you can afford Your First 10,000 Readers (closing tonight)”
  2. “Hey, forget something? Here’s 20% off.”
  3. Target: “The price dropped for something in your cart”
  4. “Mary, your Envira account is on hold!”
  5. “I’m deleting your Envira account”
  6. “Offering you my personal email”
  7. “Did you miss out on some of these new features?”
  8. “Good News: Your Pin’s price dropped!”
  9. “⚠ Unroll.Me has stopped working”
  10. “We are not gonna Give Up on You!”

Personal

According to a 2015 study by Experian Marketing Services, email subject lines that were personalized by including a name boosted open rates by 29.3% on average across all industries.

But including your subscribers name is only one way to make your subject lines more personal. You can also use casual language, share something personal, or use copy that implies familiarity or friendship.

(Just be careful not to play too many “tricks” on your subscribers by making them think that you actually are a friend!)

Here are some examples of personal email subject lines that get attention

  1. Guess: “Mary, check out these hand-picked looks”
  2. Rent the Runway: “Happy Birthday Mary – Surprise Inside!”
  3. Bonnie Fahy: “Mary, do you remember me?”
  4. Kimra Luna: “I didn’t see your name in the comments!?”
  5. John Lee Dumas: “Are you coming?”
  6. UrbanDaddy: “You’ve Changed”
  7. Influitive: “So I’ll pick you up at 7?”
  8. James Malinchak: “Crazy Invitation, I am Going to Buy You Lunch…”
  9. Brooklinen: “Vanilla or Chocolate?”
  10. Sam from The Hustle: “I love you”
  11. Ryan Levesque: “Seriously, Who DOES This?”
  12. Jon Morrow: “Quick favor?”
  13. Mary Fernandez: “you free this Thurs at 12PM PST? [guest blogging class]”
  14. Mary Fernandez: “? your detailed results…”
  15. Syed from OptinMonster: “300% increase in revenue with a single optin + a neat growth trick from my mastermind!”
  16. Revolution Tea: “Thanks for helping us”
  17. Harry’s: “Two razors for your friends (on us)”

Straightforward

When in doubt, make your subject line simple and straightforward. Contrary to what you might think, these “boring” subject lines can actually convert really well.

The key to making this work for your list is to consistently provide value in all of your emails. Don’t ever send an email unless you have something important to say: always make sure your campaigns are packed with value. If you do this, you’ll train your subscribers to open your emails no matter what the subject line says.

Here are some examples of email subject lines that get straight to the point

  1. Al Franken: “Yes, this is a fundraising email”
  2. AYR: “Best coat ever”
  3. Barack Obama: “Hey”

…and these “boring” subject lines performed the highest out of 40 million emails, with open rates between 60-87%…

  1. “[Company Name] Sales & Marketing Newsletter”
  2. “Eye on the [Company Name] Update (Oct 31 – Nov 4)”
  3. “[Company Name] Staff Shirts & Photos”
  4. “[Company Name] May 2005 News Bulletin!”
  5. “[Company Name] Newsletter – February 2006”
  6. “[Company Name] and [Company Name] Invites You!”
  7. “Happy Holidays from [Company Name]”
  8. “Invitation from [Company Name]”

Top Subject Line Keywords

There have been many studies analyzing the effectiveness of using specific email subject line keywords. Use these keywords when crafting your own email copy and subject lines to boost your open rates even further.

According to Alchemy Worx, which analyzed 21 billion emails sent by 2,500 brands, the top five most effective subject line keywords were:

  1. “upgrade”
  2. “just”
  3. “content”
  4. “go”
  5. “wonderful”

In another study from Alchemy Worx, which analyzed 24.6 billion emails, the top subject line keywords for open rates were:

  1. “jokes”
  2. “promotional”
  3. “congratulations”
  4. “revision”
  5. “forecast”
  6. “snapshot”
  7. “token”
  8. “voluntary”
  9. “monthly”
  10. “deduction”

Based on Digital Marketer’s analysis of 125 million emails they sent in 2014, some top subject line keywords to try are:

  1. “is coming”
  2. “get this now”
  3. “you have one day left”
  4. [numbers] (e.g. “7-figure plan”, “212 ideas”, “60 minutes or less”)
  5. [ellipse at the end] (e.g. “The Facebook Slap is coming…”, “Your 7-figure plan goes bye-bye at midnight…”, “Steal these email templates…”)

Adestra analyzed over 2.2 billion emails, and found the following top subject line keywords:

  1. “free delivery”
  2. “available”
  3. “new”
  4. “alert”
  5. “news”
  6. “update”
  7. “summer”
  8. “weekend”

In another study from Adestra, which looked at over 125K email campaigns, the top performing subject line keywords were:

  1. “thank you”
  2. “*|*|*|*|” (i.e. a subject line that has multiple stories delineated by pipes. For example, “Headline 1 | Headline 2 | Headline 3 | Headline 4”)
  3. “monthly”
  4. “thanks”
  5. “*|*|*|”
  6. “bulletin”
  7. “golden”
  8. “iPhone”
  9. “breaking”
  10. “order today”

Finally, a report by Smart Insights looked at a random sample of 700 million emails, and found that the top performing subject line keywords were:

  1. “introducing”
  2. “celebrate”
  3. “buy”
  4. “continues”
  5. “get your”
  6. “what…?”
  7. “won’t…?”
  8. “do…?”
  9. “can…?”
  10. “may…?”
  11. “on orders over”
  12. “orders over”
  13. “off selected”
  14. “your next order”
  15. “available”
  16. “brand new”
  17. “latest”
  18. “special”
  19. “wonderful”
  20. “great deals”
  21. “sale starts”
  22. “back in stock”
  23. “stock”
  24. “sale now”
  25. “now in”

Conclusion: Some Final Tips for Crafting Irresistible Subject Lines

Before choosing a subject line at random, keep these tips in mind for the highest possible open rates.

Most People Open Emails on Mobile

Regardless of which of the above techniques you decide to use, make sure your subject line is optimized for mobile users.

Some important tips that will help you:

  1. Keep it short and simple. use concise language.
  2. Avoid ‘no-reply’ sender name, rather keep a familiar name
  3. Avoid using ALL CAPS
  4. Segment your lists
  5. Avoid making false promises
  6. Use numbers and values
  7. Make the recipient feel special. Give an engaging pretext.
  8. Use either a question or an exclamation at a time
  9. Start with action-oriented verbs
  10. A/B test your subject lines.

Email subject lines are tricky things. What worked last month or last prospect might not work with this one. Be flexible, always be testing, and get creative for the best results.