How to Write Email Subject Lines That Get Opened

<h2>The Email Subject Line Problem</h2> <p>Your email has great content. Nobody opens it.</p> <p>That's the subject line's fault. The subject line is the gatekeeper. If it fails, nothing else matters.</p> <p>Most people spend 10 seconds writing a subject line after spending hours on the email body. That ratio is backwards.</p> <p>This guide will show you how to write email subject lines that get opened. The techniques work for newsletters, campaigns, and one-on-one outreach.</p> <h2>How Email Clients Display Subject Lines</h2> <p>Before you can write a good subject line, you need to know how it displays.</p> <p><strong>Gmail desktop:</strong> Shows 70 characters <strong>Gmail mobile:</strong> Shows 40 characters <strong>Outlook desktop:</strong> Shows 60 characters <strong>Outlook mobile:</strong> Shows 35 characters <strong>Apple Mail:</strong> Shows 65 characters</p> <p>Your subject line needs to work in 35-70 characters. That's your canvas.</p> <h2>The Subject Line Formula</h2> <p>The best subject lines follow a simple formula:</p> <p><strong>[Curiosity/Question/EmoEmo] + [Specific Detail] = Opens</strong></p> <p><strong>Examples:</strong></p> <ul> <li>"Are you making this headline mistake?" (question + specific mistake)</li> <li>"The real reason your emails aren't getting opened" (curiosity + specific reason)</li> <li>"Your weekly headline ideas are inside" (specific detail + what it is)</li> </ul> <p>The specific detail is what separates good subject lines from mediocre ones. "Weekly ideas" is vague. "Your weekly headline ideas" is specific. "10 headline ideas for this week" is even better.</p> <h2>Techniques That Work</h2> <h3>Technique 1: Ask a Question</h3> <p>Questions engage the reader's brain. The reader has to think about the answer.</p> <p><strong>Weak:</strong> "New headline ideas for you"</p> <p><strong>Strong:</strong> "What if your headlines were 3x better?"</p> <p><strong>Why it works:</strong> The question creates engagement. The reader has to form an opinion.</p> <h3>Technique 2: Create a Curiosity Gap</h3> <p>Withhold information to create tension.</p> <p><strong>Weak:</strong> "Headline writing tips"</p> <p><strong>Strong:</strong> "The headline formula most marketers ignore"</p> <p><strong>Why it works:</strong> "Most marketers ignore" creates curiosity. The reader wants to know what's being ignored.</p> <h3>Technique 3: Use Specific Numbers</h3> <p>Numbers create credibility and specificity.</p> <p><strong>Weak:</strong> "Tips for better headlines"</p> <p><strong>Strong:</strong> "7 headline formulas that doubled our open rate"</p> <p><strong>Why it works:</strong> "7" and "doubled" are specific. The reader can visualize the outcome.</p> <h3>Technique 4: Trigger Urgency</h3> <p>Urgency creates action.</p> <p><strong>Weak:</strong> "Our latest newsletter"</p> <p><strong>Strong:</strong> "Last chance: This week's headline ideas expire tonight"</p> <p><strong>Why it works:</strong> "Last chance" and "expire tonight" create urgency. The reader acts or loses something.</p> <h3>Technique 5: Personalize</h3> <p>Personalization makes emails feel less like broadcasts.</p> <p><strong>Weak:</strong> "Weekly marketing tips"</p> <p><strong>Strong:</strong> "[First Name], your competitors are reading this"</p> <p><strong>Why it works:</strong> The personalized opener ("[First Name]") and social proof ("your competitors") create relevance.</p> <h2>What Doesn't Work</h2> <h3>Trigger Words That Get You Filtered</h3> <p>Some words trigger spam filters or promotional tab placement:</p> <ul> <li>"Free" (often)</li> <li>"Buy now"</li> <li>"Earn money"</li> <li>"Act now"</li> <li>Excessive exclamation points</li> <li>ALL CAPS</li> </ul> <h3>Misleading Subject Lines</h3> <p>Your subject line must match your content. If you promise "free templates" and deliver a sales pitch, you destroy trust.</p> <h3>Too Clever</h3> <p>Puns, wordplay, and excessive cleverness can backfire. The subject line should create curiosity, not confusion.</p> <h2>Subject Line Formulas</h2> <h3>For Newsletters</h3> <p>"[Number] things worth knowing this week"</p> <p><strong>Example:</strong> "5 things worth knowing about headlines this week"</p> <h3>For Educational Content</h3> <p>"[Question] — [answer or hint]"</p> <p><strong>Example:</strong> "Are your subject lines too long? Here's the fix"</p> <h3>For Promotional Emails</h3> <p>"[Specific outcome] for [specific audience]"</p> <p><strong>Example:</strong> "Free headline templates for SaaS marketing teams"</p> <h3>For Re-engagement</h3> <p>"We miss you — [specific offer]"</p> <p><strong>Example:</strong> "We miss you — here's what you missed in headlines"</p> <h2>Testing Subject Lines</h2> <p>Always test your subject lines. What works in theory often fails in practice.</p> <p><strong>A/B test setup:</strong> - Split your list 50/50 - Send variation A to half your list - Send variation B to half your list - Use the winner for the full send</p> <p><strong>What to test:</strong> - Question vs. statement - Long vs. short - Personalized vs. generic - With number vs. without - Curious vs. direct</p> <h2>FAQ: Email Subject Lines</h2> <p><strong>Q: How many characters should an email subject line be?</strong></p> <p>A: 40-50 characters. This ensures display across all email clients and devices.</p> <p><strong>Q: Should I use emojis in subject lines?</strong></p> <p>A: Test them. Emojis can increase open rates in some audiences and decrease them in others. B2B audiences tend to prefer text-only subject lines.</p> <p><strong>Q: Should I personalize subject lines?</strong></p> <p>A: Yes, if you have the data. "[First Name]" personalization can increase open rates. But generic personalization ("Hey you") feels fake.</p> <p><strong>Q: How many subject lines should I test?</strong></p> <p>A: Minimum two. Write your top three and A/B test the best two.</p> <h2>Do This Now</h2> <ol> <li>Look at your last five email subject lines.</li> <li>Score each on curiosity, specificity, and urgency.</li> <li>Rewrite the weakest using the techniques in this guide.</li> <li>A/B test your rewritten subject line against your original.</li> <li>Track open rates to see which approach works.</li> </ol> <p>Your subject line is the most important sentence in your email. Spend more time on it.</p> <hr /> <p><em>Generate email subject lines that get opened. <a href="/tools/email-subject-line-analyzer">Try Punchd</a> — analyze subject lines for open rate potential.</em></p>