Email Subject Line Tester
Test and optimize your email subject lines with AI-powered analysis. Get instant scoring, spam detection, and suggestions to boost open rates.
What Makes a High-Performing Email Subject Line?
Email subject lines are the gatekeepers of your email marketing success. With 64% of recipients deciding whether to open an email based solely on the subject line, crafting compelling subject lines is crucial for campaign performance.
Best Practices
- • Keep it 40-50 characters (6-10 words)
- • Front-load important information
- • Use personalization (22% higher open rates)
- • Include numbers or questions
- • Add a single relevant emoji (73% improvement)
- • Create curiosity without clickbait
- • Test with A/B testing
What to Avoid
- • Spam trigger words (free, winner, urgent)
- • ALL CAPS or excessive punctuation!!!
- • Misleading or clickbait content
- • Generic greetings (Dear customer)
- • Too long (over 70 characters)
- • Multiple emojis
- • Overpromising or hype
Email Subject Line Impact Statistics (2026)
Higher open rates with personalization
More opens when including numbers
Improvement with single emoji
Better performance with questions
Mark spam based on subject line
Optimal character count
Average Open Rates by Industry (2026)
Note: Open rates in 2026 account for Apple Mail Privacy Protection (MPP) inflation. Average B2B open rate is 15-25%.
High-Performing Subject Line Examples
"[Name], your Q4 marketing strategy inside"
✓ Personalized ✓ Optimal length ✓ Clear value
"5 ways to boost conversions this week"
✓ Specific number ✓ Clear benefit ✓ Urgency
"Ready to 3x your email open rates?"
✓ Question ✓ Specific outcome ✓ Engaging
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