Writing Email Subject Lines That Get Opened: Crafting Catchy Subject Lines to Boost Open Rates
Effective email marketing starts with a great subject line. With over 347 billion emails sent worldwide every day, the subject line is the first impression that determines whether recipients open or ignore your message.
In fact, 41% of marketers consider email their most effective channel, and a well-crafted subject line is the key to capturing attention. Clear, concise, and relevant subject lines can pique curiosity, convey value, and connect with subscribers, driving open rates into the high teens and beyond.
By following proven best practices – such as personalization, brevity, and urgency – businesses of all types (marketers, small businesses, e-commerce brands, etc.) can significantly boost open rates.
This article covers the latest research and expert advice on writing email subject lines that get opened, with practical tips and guidelines for any email marketing campaign.
Why Email Subject Lines Matter
Email subject lines are a critical part of email marketing. They serve as the gateway to your content, influencing whether a subscriber opens your email or deletes it unseen. Studies consistently show that subject lines directly impact open rates.
For example, one analysis found that personalized subject lines (including a recipient’s name or other unique detail) can increase open rates by about 26%. Likewise, adding urgency-related words like “limited time” or “act now” can boost opens by roughly 22%.
Emotive touches such as emojis can also help – emails with an emoji in the subject saw a 56% higher open rate in one study. These findings underscore that even small changes in wording or style can have a large effect on engagement.
Real-world metrics highlight how important open rates are. Across industries, average email open rates typically range 17–28%, with a healthy campaign aiming for the higher end of that range.
Some sectors (e.g. government or hobby newsletters) even average ~28% opens. Because most people check email on smartphones (85–90% of users, yielding open rates around 40% on mobile), brevity and clarity in subject lines are essential.
Poorly written or irrelevant subject lines end up ignored in inboxes flooded with messages. In short, the subject line is your best (and often only) chance to stand out in a crowded inbox.
Here are some key statistics highlighting the impact of subject lines:
- Personalization Pays Off: Emails with personalized subject lines (e.g. including the recipient’s name or other personal detail) saw ~26% higher open rates, and 72% of consumers say they are more likely to open personalized messages.
- Brevity Works: Subject lines of about 6–10 words achieved the highest open rate (~21%) in one study, likely because they remain concise and mobile-friendly.
- Emojis Boost Interest: Including an emoji in a subject line correlated with a 56% lift in open rate, capturing attention visually (when used appropriately).
- Urgency Drives Action: Adding urgent phrases (“Last chance”, “Ends today”) can increase opens by ~22%, as they tap into FOMO (fear of missing out).
These findings show that small changes – personalization tokens, a few well-chosen words, or an emoji – can tip the scales. The next sections explain the best strategies for writing subject lines that consistently get your emails opened.
Key Strategies for Writing Email Subject Lines
To boost open rates, focus on the following key elements when crafting subject lines. These strategies apply across industries and business sizes:
- Personalization and Relevance: Tailor the subject line to the recipient whenever possible. Personalization can be as simple as inserting a subscriber’s name or location, or as sophisticated as referencing past purchases or interests.
Relevant subject lines make the email feel one-to-one instead of generic. Research shows personalized subject lines improve open rates by around 26%. Moreover, marketing experts note that “hyper-personalization is key to email marketing in 2024,” and AI tools can help craft these customized lines.
When a subject line resonates with something the recipient cares about (e.g. their name, recent activity, or preferences), they are much more likely to click. - Brevity and Clarity: Keep it short and to the point. Long, wordy subject lines lose impact, especially on mobile where only the first few words are visible. Aim for around 6–9 words (≤60 characters) when possible.
Studies confirm that subject lines in the 6–10 word range achieve the highest opens. In contrast, lines over 11 words tend to see lower open rates. Always front-load the most important words (benefit or keyword) at the beginning so they don’t get cut off.
For example, rather than “For a Limited Time: 50% Off Winter Gear”, write “50% Off Winter Gear – Limited Time Offer” so the key message appears first. In general, clear and specific phrasing outperforms clever but vague wording. - Urgency and Scarcity: Words that convey scarcity or time-sensitivity can motivate opens. Phrases like “limited time only,” “last chance,” “exclusive offer,” or countdown timers imply that there is something to lose by not opening immediately.
One study found that adding such urgent terms lifted open rates by about 22%. Similarly, highlighting limited inventory (“only 2 seats left!”) can spur action. These tactics create FOMO (fear of missing out) and prompt recipients to open before the opportunity expires.
Caution: Use urgency honestly and sparingly. Overusing all-caps or repeatedly crying wolf can desensitize readers or trigger spam filters. Reserve urgent language for genuinely limited or time-bound offers, and mix in other types of subject lines as well. - Curiosity and Value Proposition: A subject line should hint at something valuable inside the email. Tease interesting content or pose a question that the email will answer. This creates a curiosity gap – the difference between what the recipient knows and what they’ll learn by opening the email.
The Enchanting Marketing blog defines the curiosity gap as “the space between the information we’re given (what we know) and the information that’s initially withheld (what we don’t know)”.
When people sense they’ll learn something useful or surprising, they’re more likely to open up. For example, a line like “Boost Your Productivity in 5 Minutes” suggests a benefit (value) but doesn’t give away the answer, enticing the recipient to click.
However, make sure the body of the email delivers on the promise – readers dislike deception. Also, align the content with the subject; if the subscriber trusts your emails already, invoking curiosity about your brand story or solutions can work well. - Actionable and Clear Language: Use strong verbs and clear wording that communicates the benefit or action. Subject lines that describe exactly what’s inside tend to perform better than cryptic or “cute” ones.
For instance, instead of “Fall Into Savings,” use “Save 20% on Fall Clothes” to clearly state the value. Phrases like “Download your guide,” “Register now,” or “Learn how to…” tell the subscriber what they will get.
As Mailchimp advises, “sometimes it’s better to be direct and descriptive than trendy”. Busy readers appreciate knowing why opening the email is worth their time.
Avoid vague slogans and instead highlight specific offers, tips, or information. In summary, make the subject line informative: explain the hook or offer so readers immediately grasp the relevance. - Mobile Optimization: Since most emails are opened on mobile devices, ensure your subject line is mobile-friendly. Test how your subject looks on smaller screens – for example, the iPhone Mail app displays roughly 5–6 words or ~40 characters before truncating.
If a subject is cut off, the remaining text should still make sense. Use line breaks judiciously if needed. Given limited space, prioritize the most important words first and keep the message concise. Avoid filler words at the end that may not display on mobile. - Emojis (When Appropriate): Emojis can make your subject line stand out in a text-heavy inbox. Studies show that adding an emoji to the subject line can increase open rates by over 50%.
However, use them thoughtfully: one well-placed emoji can add color or humor, but multiple emojis may look spammy. Mailchimp recommends no more than one emoji per subject line, using it to supplement the message rather than replace key words.
Always test how the emoji renders on different devices and email clients, since they may appear differently or not at all.
Ultimately, an emoji should align with your brand tone and audience – e.g. a shopping bag emoji for sales, or a party popper for celebrations. If used tastefully, an emoji can draw the eye and make the subject line more engaging. - Test and Iterate (A/B Testing): There’s no one-size-fits-all subject line formula, because every audience is different. What works for one list may fail on another. That’s why A/B testing (split testing) is crucial.
Always test multiple subject lines on a small segment of your audience before sending to everyone. Try variations in length, tone (casual vs. formal), personalization, question vs. statement, emojis vs. none, etc.
As HubSpot notes, “you should always A/B test your highest-stakes subject lines and tweak the wording according to your results.”. Use your email platform’s analytics to compare open rates and identify winners.
Over time, accumulate data on what elements (words, punctuation, formats) consistently outperform for your specific subscribers. By iterating based on real results, you’ll refine your approach and continually boost engagement.
The table below summarizes these strategies and their impacts:
| Subject Line Strategy | Why It Works / Impact |
|---|---|
| Personalize content (name, place, product) | Increases relevance. Personalized lines see ~26% higher open rates and make recipients feel addressed personally. Use merge tags for name/location. |
| Keep it short (≤6–10 words) | Short lines (6–10 words) achieved highest opens (~21%). Concise subjects fit mobile displays (Mail recommends ≤9 words). Longer lines dilute impact. |
| Convey urgency/scarcity | Words like “limited time,” “last chance,” or countdowns prompt immediate opens (≈22% lift). Creates FOMO, but should be genuine. |
| Spark curiosity or value | Teasing content (curiosity gap) entices opens. Highlight a clear benefit or intriguing idea so readers want to learn more. |
| Use actionable language | Action verbs and clear offers grab attention. Direct value statements (e.g. “Save 20%”) outperform vague phrasing. |
| Limit punctuation/symbols | Excessive punctuation or symbols (!!!, $$$, etc.) looks spammy. Mailchimp advises ≤3 punctuation marks to avoid spam filters. |
| Test subject lines | Results vary by audience. A/B testing shows what truly works. Always test length, tone, emojis, questions, etc., to optimize performance. |
In summary, the best email subject lines combine personalization, brevity, clarity, and a compelling reason to open. Use these tactics as guidelines, but always tailor and test with your own list.
Additional Best Practices
Beyond the core strategies above, consider these general tips that apply across email marketing:
- Match the Content: Ensure the subject line accurately reflects the email content. Misleading or clickbait subject lines may get the open, but hurt trust and future open rates. The email should immediately deliver on the subject’s promise.
- Segment Your Audience: If you have diverse subscribers (e.g. different interests or buying stages), segment your list and customize subject lines per group. What appeals to one segment may not to another. Segmentation combined with personalization can dramatically raise relevance and opens.
- Localize and Locale: If your audience spans regions or languages, consider localization. Mentioning the subscriber’s city or using the local language can catch their eye. For example, a nearby event invite (“Seattle Breakfast Meetup?”) or festive greetings in their language adds a personalized touch.
- Avoid Spam Triggers: Email Service Providers (ESPs) filter out suspected spam. Words like “free,” “guarantee,” or excessive exclamation points can trigger filters. Also avoid misleading elements (like “Re: [Name]” to impersonate a thread).
Mailchimp recommends limiting punctuation and special characters to avoid looking spammy. According to MailMunch, emails that look spammy may never reach the inbox at all. Keep language professional and straightforward to maintain deliverability. - Consider Preview Text: While not strictly part of the subject line, the preview text (the snippet shown after the subject) works together with it. Use it as a “second subject line” to add context or continue the tease.
For example, if the subject is “Your week just got better”, the preview might say “Enjoy 30% off our summer collection.” This tandem can boost openings. - Timing and Frequency: No subject line is evergreen. Refresh your subject line strategy for seasonal events, holidays, or new trends.
Also, don’t fatigue subscribers by sending too many emails in a row, even with different subjects. Monitor engagement and adjust frequency to maintain interest.
By incorporating these practices, email marketers, small business owners, and e-commerce brands alike can craft subject lines that resonate with their audience and stand out in inboxes.
Remember that email marketing in general depends on building a relationship: consistent value and trust. The subject line is the first step in that journey.
Frequently Asked Questions
Q.1: How long should email subject lines be?
Answer: Keep subject lines concise. Research suggests the sweet spot is around 6–10 words (or ≤60 characters). Very short lines (<5 words) can work if extremely clear (e.g. “50% Off Now”), but often risk lacking context.
Also consider mobile: most phones display ~40 characters (~6 words) before truncating. In practice, aim for 5–9 words and front-load key info so nothing important gets cut off. Always A/B test length with your audience, as some brands find slightly longer or shorter lines work better for them.
Q.2: Should I use my recipient’s name in the subject line?
Answer: Personalizing with the recipient’s name can grab attention and make the email feel addressed specifically to them. One study reported personalized lines can lift open rates by about 26%. However, using first names alone has diminishing returns; intelligent personalization (like referencing a recent purchase or location) often yields bigger gains.
Mailchimp suggests using merge tags for names or location in relevant contexts (e.g. “John, your Seattle event starts soon”). In short, personalization usually helps, but ensures it adds real relevance rather than sounding generic. Combining name personalization with other personal data (purchase history, interests) creates the strongest effect.
Q.3: Are emojis good in email subject lines?
Answer: Used judiciously, emojis can increase visibility. Data shows emails with an emoji in the subject can see open rates rise by 50-60%. The emoji acts like a visual highlight in the inbox. However, only use them when appropriate.
Limit to 1 emoji (Mailchimp recommends no more than one), and make sure it fits the message (e.g. a 🎉 for celebration, 💸 for sales). Avoid replacing key words with emojis in a confusing way.
Also remember: not all devices or clients display emojis the same way – test to ensure it looks acceptable everywhere. In summary, one well-chosen emoji can make your subject pop, but overusing them may seem unprofessional or trigger spam filters.
Q.4: How do I improve my open rates?
Answer: Improving open rates requires both strategic subject lines and overall email best practices. Start by writing compelling subject lines as described above. Use segmentation to send only relevant emails (so more people open them).
Build trust by delivering promised value – a history of good content makes recipients more likely to open future emails. Also focus on timing and frequency: send when your audience is most active, and avoid over-mailing so people don’t tune you out.
Crucially, always test your subject lines. What works varies by industry and audience. Use A/B tests to compare different wording, tone, or send times. Finally, track metrics comprehensively.
While open rate is a key indicator, also monitor click-through and conversion rates to ensure opens lead to engagement. Keep iterating on your approach until your open rates exceed the typical 17–28% range for your industry.
Q.5: What words or tactics should I avoid in subject lines?
Answer: Avoid clichés and spam-trigger words. Overused phrases like “You won’t believe this,” or repeatedly using ALL CAPS and exclamation points (!!!) can annoy readers or trip spam filters. Similarly, be careful with words like “Free,” “Earn money,” or “Act now” — they aren’t off-limits, but should be used naturally and sparingly.
Too many symbols or special characters can make your email look like spam to both people and filters. Mailchimp specifically advises limiting punctuation marks to three or fewer.
Lastly, don’t make false promises. If the subject says “50% Off Entire Store,” ensure that’s true. Honesty in your subject line builds trust and keeps subscribers engaged long-term.
Q.6: How important is A/B testing for subject lines?
Answer: A/B testing is essential. No matter how many best-practice tips you follow, the only way to know what truly resonates is to test it with your audience. Split your list (often 50/50) and send different subject lines to each half.
Compare the open rates to see which performed better. You can test anything: personalization vs no name, short vs long, emoji vs none, question vs statement, etc. Over time, you’ll learn the preferences of your subscribers.
For example, one list might respond better to playful questions, another to straightforward commands. Testing also helps overcome assumptions – sometimes your gut feeling may not match reality. As HubSpot advises, rely on data rather than intuition for subject lines. Make testing an ongoing habit for continual improvement.
Conclusion
In today’s crowded inboxes, writing email subject lines that get opened is both an art and a science. The subject line is the first impression of your email – a single sentence that can make or break your campaign.
By applying the strategies outlined here, any organization – from solo entrepreneurs to large e-commerce brands – can improve their email open rates. Personalization, relevance, urgency, conciseness, and clarity should guide your approach.
Use data and testing to refine your style, and always deliver on the subject line’s promise. When crafted effectively, a compelling subject line not only boosts open rates but also primes recipients to engage with your content.
In short, take the time to craft better subject lines – it will pay dividends in engagement, conversions, and ultimately business success.