Good subject lines are brief, speak directly to the reader’s interests and frequently feature calls to action or personalization.
Don’t use wishy-washy wording or too much hype. When you line up subject lines with the email’s content, you build trust and motivate readers to act.
My guide below takes a deep dive through actionable ways to polish your email subject writing.
The First Impression
In email, the subject line is your first impression on a recipient. It’s the online equivalent of a handshake or an introduction — it forms a reader’s impression in seconds. These moments, research reveals, are decisive.
Attitudes crystallize quickly and that first impression can be the difference between your email being opened or ignored. With inboxes inundated and nearly half of all emails read on mobile, writing a short, powerful subject line is more important than ever.
A compelling first impression can intrigue, impress a need or establish relevance, making the reader more likely to read on.
Beyond Opens
Subject lines don’t just convince people to open your emails — they establish the tone for the content within. A killer subject line matches the email intent, whether it be to advertise something, provide assets, or make big news.
For instance, a subject like "Exclusive Offer: 20% Off Ends Tonight" not only drives clicks but clearly communicates the email's intent. Click throughs and much engagement is driven by subject lines.
A powerful line can lead readers to do what you want them to do – click or buy. Conversely, misleading subject lines—like using "Urgent: Account Issue" for a promotional email—can erode trust and damage long-term engagement.
Openness is the first step to a relationship with your audience.
Brand Voice
We’ve found that being consistent in tone and style with your email subject lines and content helps to build your brand. For instance, a cheeky brand could be funny, "Oops, You did something in your cart," whereas a more formal brand might like it straightforward, "Your Invoice for September 2023.
Consistency in your brand voice builds familiarity and trust, both of which can increase your open rates over time. Customizing subject lines for your audience is just as critical.
Think about what your readers like and need—formal for a corporate crowd, casual for a younger audience. Memorable and pertinent communication builds loyalty and engagement.
Trust Signal
Using a known sender name is vital to trust. We’re more apt to open one from someone we trust. For instance, "Tech Insights from Drew Parker" emphasizes professionalism and trustworthiness.
Transparent truth in subject lines builds trust as well. Stay away from stuff like "You’ve Won!" – it’ll look spammy and damage your reputation. Instead, customize notes or promote offers, for example, "Hey Alex, Your Free Guide is here," to forge a trusted bond.
Crafting Compelling Subject Lines
Your subject line is your email’s front door. It’s the initial impression a recipient receives and is key to whether your email gets opened or overlooked. Make it like a book title — catchy and purposeful. Here are some ways to write subject lines that convert.
- Personalization, clarity, curiosity, urgency and value are all ways to craft compelling subject lines.
- Customize subject lines to suit the email’s objective and audience.
- Experiment with subject lines to see what works best.
- Add in battle-tested strategies like emojis, humor and brevity.
Personalization
Personalized subject lines strike the right chord on the right note.
Adding the recipient’s name–such as ‘Alex, Here’s Your Exclusive Offer’–instantly creates a bond. Segmentation adds another layer of relevance — for instance, reaching out to fitness buffs with ‘Your Customized Workout Plan Is Ready.’
Personalized emails beat generic ones by as much as 25% higher response rate. Avoid clichés such as ‘Don’t Miss Out!’ Instead, personalize on previous behavior or interest. For example, ‘You Left This in Your Cart’ targets abandoned shopping behavior.
Clarity
Clarity ensures recipients understand the value of your email.
Obscure or complicated lines such as “An Important Update” are dismissed. Instead, be direct: “Save 15% on Your Next Purchase.” This sets clear expectations and conveys advantages.
Fifty-five percent of emails are opened on mobile devices, so keep it under 50 to prevent truncation! Short subject lines such as, “New Recipes for Busy Weeknights” are more digestible and work better.
Curiosity
Curiosity-driven subject lines spark intrigue without over-explaining.
Compelling questions, such as ‘What’s Missing From Your Morning Routine?’, are click bait. Open loops–lines that tease but don’t tell–work well. For example, ‘The Secret to Better Sleep Is Here.’
Don’t be afraid to get funny or punny, like ‘Don’t Let This Deal Snooze,’ to differentiate. Continue testing for balance–too much mystery can annoy readers.
Urgency
Urgency motivates immediate action, but overuse can backfire.
Phrases like “Ends Tonight: 50% Off” or “Only 3 Left in Stock” create a sense of scarcity. Emphasizing exclusivity – like ‘Early Access to Members Only Sale’ – really drives clicks.
Sprinkle urgency sparingly to keep your credibility, as repetitive tactics may desensitize recipients over time.
Value
Value-focused subject lines promise tangible benefits.
If you can, use numbers or details, like “Increase Productivity by 30% This Week,” which makes the benefit explicit. Emphasize special information or offers, such as “Free Shipping – Today Only,” to entice.
Make certain the email fulfills its promise. Deceptive subject lines destroy trust and damage future campaigns.
Advanced Psychological Triggers
These triggers can supercharge email engagement by tapping into human emotions, logic, and social instincts. Here’s a summary of the important triggers and how to use them.
Social Proof
Types of social proof include testimonials, user statistics, endorsements, or media mentions. Talking about customer success stories in the subject line can humanize the e-mail.
For instance, “Watch how Sarah saved $1,000 with our tool!” brings attention to big numbers, like “Used by 50,000 professionals,” which reinforces authority.
Terms such as ‘Most popular’ or ‘Top-rated choice’ attract the recipient’s lizard brain desire to jump on a bandwagon.
Reciprocity
Providing value first builds the feeling of indebtedness. For example, headlines such as “Your complimentary [topic] guide” or “Take 20% off—because we like you!” establish a giving vibe.
Adding special perks, like “Unlock members-only deals today,” can provide an additional incentive for reciprocation.
Don’t use hyperboles such as “100% guaranteed results!” — they kill trust. By establishing a transaction relationship, reciprocity levers an instinct to repay.
This is effective in combination with personalization because this way, the recipients feel like you’re offering something for them specifically.
Authority
Authority adds credibility through citing expert sources or expert testimonials. Headlines such as “Endorsed by leading experts” or “Proven tactics for victory” convey trust.
You can make the positioning of the email as a trusted resource more authoritative with headlines like “Proven tips for boosting your productivity.
Citing industry leadership, such as “From the makers of [famous product]” builds trust. Realness is key—hyperbolized assertions can sap faith and decrease click through rates.
Directing your attention to hard credentials or famous supporters makes sure the tactic stays compelling and credible.
Combining Triggers
Stacking triggers multiplies their power. For example, a subject line like “50,000 users agree: Download your free guide now!” merges social proof with reciprocity, creating a compelling call to action.
Similarly, integrating urgency with exclusivity, such as “Last chance: VIP access for today only,” can drive immediate clicks.
The Global Inbox
Our global inbox, after all, is a battleground where millions of emails struggle for our attention on any given day. With close to 50% of all emails opened on mobile devices, and studies demonstrating that subject lines between 61-70 characters garner the most opens, writing email subject lines has evolved into an art and science.
A persuasive subject line can rise above the din, boost conversions by tackling the demands of multiple audiences, devices and cultures.
Mobile View
Subject lines need to adjust for mobile screens. Since mobile devices don’t have much space, this means it’s really important to keep subject lines in the 33-43 character range to prevent truncation. This guarantees that the whole message is readable in one glance, increasing your chances of a response.
For example, a concise subject line like "Flash Sale: 50% Off Today!" is more effective than a lengthy one that might get cut off mid-sentence. Testing your subject lines in different email clients like Gmail or Outlook is just as key. Differences in formatting impact how the subject line displays to users.
Preheader text—those preview words displayed next to the subject line—should be exploited. Example: in our tests, sending “Exclusive Invite Inside” with a preheader “RSVP now to secure your spot” creates a winning combination!
Cultural Context
Email marketers have to think about the global culture. What drives open rates in one region might be missed elsewhere. For instance, idioms or humor that make sense in the US could baffle recipients in non-English speaking locations.
You can overcome this by using localized key words or phrases, like “Summer Deals in Tokyo” for a Japanese reader. Steering clear of culturally sensitive words is just as important. Words or phrases that appear innocent in one setting might have unintended baggage in another.
Conducting focus groups or subject line testing on analytics tools can help you catch these pitfalls. For example, prior to a campaign launch, a subject line such as “Celebrate Diwali with Us!” needs to be checked for its relevance and cultural sensitivity.
Inclusivity and Testing
Relevance and inclusivity in global email marketing go hand-in-hand. Personalization, like including the recipient’s name or interests, can forge a stronger connection. For example, ‘Maria, Your Special Deal Is Waiting’ sounds more personalized than a standard salutation.
I test my subject lines with people of different ages, sexes and backgrounds to make sure they resonate universally. Tools like A/B testing platforms can provide insights into what works best, whether it's a sense of urgency ("Last Chance to Save!") or timeliness ("Trending Now: New Arrivals").
Common Subject Line Pitfalls
Precision and strategy are important when writing email subject lines. Screw this up, and you’ll blow even the most carefully designed email campaigns. Below, we dig into common subject line pitfalls and practical ways to fine-tune your strategy.
Deceptive Clickbait
Deceptive subject lines that don’t match the email’s content can break trust irreparably. For example, a subject of “Exclusive Free Gift Inside!” that delivers some run of the mill promotional offer exasperates recipients. This disconnect leads to an unsubscribe rate of up to 30.4% since recipients feel lied to. Trust, when lost, is hard to reclaim.
Instead, be candid. Consider what’s in it for the reader — if your email is about a 10% discount, write “Save 10% on Your Next Purchase”. Testing your subject lines for honesty can help align them with your email’s intent. This establishes trust and sustained interest, which is significantly better than a transient increase in opens.
Overused Phrases
Clichés such as “Act Now!” or “Don’t Miss Out!” just don’t get noticed in our jam-packed inboxes of the 21st century. Clichés blend in with the clutter, lowering your open rates. Worse, abusing tricks like first-name personalization can numb recipients to such optimizations, making them useless eventually.
To be unique, use descriptive and inventive wording. For example, replace "Limited-Time Offer" with "48 Hours Only: Extra 15% Off Winter Gear." Keep your tactics fresh with subject lines. They respond better to originality, which can dramatically increase engagement.
Poor Formatting
Too much punctuation, all caps or emoji overload will make them look unprofessional. For instance, HURRY!!! DEALS!!! 🛍️ distracts instead of captivates. Subject lines that are too long run the risk of getting truncated, particularly on mobile devices which have a display limit of approximately 55 characters.
To be professional, keep subject lines short, preferably less than 50 characters. For example, "New Arrivals: Shop Winter Styles Now." And always test formatting across multiple email clients. Appropriate punctuation, grammar and spelling add to the credibility of your note, showing attention to detail and respect for the reader.
The Importance of Clarity
Generic or too promotional cause confusion and alienate recipients. For example, “Big News!” offers no context, and “50% OFF!!!!!!!!” feels pushy. These tricks result in diminished open rates and fatigue.
Instead, be explicit about what’s in the email, demonstrating that your message is relevant and respects one’s time.
Measure and Refine
If you want to consistently high CTRs, it’s important to treat email subject line creation as an iterative process. Measuring and refining are the key to success! By really digging into performance data and taking action on insights, marketers can keep their email campaigns effective, relevant and engaging.
A/B Testing
A/B testing is a crucial subject line effectiveness tool. By generating two or more subject lines and delivering them to different slices of your audience, you can measure which is most effective. For example, experimenting with a lighthearted tone versus a serious one could uncover what works best with your recipients.
A/B test results can help you with future campaigns by showing what your preferences are — for example, the best word choice or tone. In your A/B tests, pay special attention to performance figures such as open rates and click-through rates. Open rates can tell you how well a subject line stands out, click-throughs tell you how well it drives engagement.
Don’t test too many things at once, or you won’t know what made the difference. For instance, if you’re testing tone and length in the same experiment, your insights will be fuzzy.
Key Metrics
Knowing your performance is key to refining your subject lines. Below is a table of key metrics and their significance:
Analytics can reveal even more, including how recipients are behaving and what they like. For example, if unsubscribe rates are high, you might find subject lines are misleading or irrelevant, and adjust accordingly to ensure a healthy subscriber list.
Concentrate on what matters to your own objectives, be it engagement or sales.
Iterative Improvement
Refinement is never done. By measuring the hits and misses, you’ll always be able to refine your subject lines. For example, if a short, 40-character subject line beats a longer one, you know what to do next. Likewise, mixing in popular trends such as seasonal or personalized themes can keep your emails feeling fresh.
Don’t forget that personalization, like the use of a recipient’s name, doesn’t necessarily equate to higher open rates. Flexibility is important. What works today may not work tomorrow.
Your approach should be something you return to regularly — it’s the basis for long-term success in email marketing.
Conclusion
Powerful subject lines cause emails to pop. They catch attention, arouse curiosity, and inspire action. An effective, compelling subject line resonates with readers. It establishes the mood before they even click. We test and refine these lines to get better results over time. Tiny adjustments can make a huge difference in how your audience reacts.
Notice what works globally. Different audiences will respond differently – adapt to them. Steer clear of errors such as being too ambiguous or too witty. Make it concise, clear and appropriate.
Begin testing your own subject lines. Monitor what receives the optimal reaction. Continue to study, refine and evolve. Better subject lines = better connections with your audience every time you hit send.
Frequently Asked Questions
What makes a good email subject line?
A great subject line is obvious, brief and pertinent. It’s attention-getting and intriguing and open-inducing. Personalization and action words generally do the trick.
How long should an email subject line be?
Keep subject lines 6-10 words or less than 50 characters. This way they are fully readable on the majority of devices yet still short and catchy.
Why are subject lines important for click-through rates?
Subject lines are the first impression. A good one makes open rates go up because then you’ve got a better chance of getting your content read and clicked.
Should I use emojis in email subject lines?
Emojis are excellent for grabbing attention and infusing personality but again, use them sparingly. Be certain they’re consistent with your brand and audience.
What are common mistakes to avoid in subject lines?
Don’t use all caps, too much punctuation, or any bait and switch type language. Overusing “salesy” words will reduce your engagement or get your messages flagged as spam.
How can I measure the success of my subject lines?
Monitor open rates, click-throughs, and test various subject lines a/b. This aids in determining what clicks most with your readers.
Can psychological triggers improve subject lines?
Sure, things like curiosity or urgency or exclusivity are good engagement triggers. For instance, words such as ‘limited time’ or ‘don’t miss out’ have a sense of urgency, which can prompt readers to take action.
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About the author
Gabriel Both
SEO Manager
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