Email Subject Line Tester Tool
Score your subject lines for clarity, curiosity, and spam risk. Test email subject lines to improve open rates and ensure they avoid spam filters before sending.
Test Your Subject Line
How to Use the Subject Line Tester
Follow these simple steps to test and optimize your email subject lines:
Enter your subject line
Type or paste your email subject line into the input field. You can test any subject line length or style.
Click Test Subject Line
Click the "Test Subject Line" button to analyze your subject line. The tool will score it for clarity, curiosity, and spam risk.
Review your scores
Review the detailed scores for clarity, curiosity, and spam risk. The tool also provides alternative subject line suggestions.
Optimize and retest
Use the suggestions to improve your subject line, then test again to see how your scores improve. Aim for high clarity and curiosity with low spam risk.
Why Subject Line Testing Matters for Open Rates
Subject lines are the first thing recipients see and determine whether your email gets opened. Testing subject lines helps you create compelling, clear subject lines that improve open rates while avoiding language that triggers spam filters.
- Improve open rates by creating clear, compelling subject lines
- Avoid spam filters by identifying problematic language before sending
- Increase engagement by optimizing for curiosity and clarity
- Save time by catching issues before sending campaigns
- Optimize for mobile by ensuring subject lines display well on all devices
How Subject Line Testing Works
Our subject line tester analyzes multiple factors to provide comprehensive scoring:
- Length analysis: Checks if your subject line is optimal length for display across email clients
- Spam word detection: Identifies words and phrases that commonly trigger spam filters
- Clarity scoring: Evaluates how clear and specific your subject line is
- Curiosity assessment: Measures how engaging and compelling your subject line is
- Best practices check: Reviews capitalization, punctuation, and formatting against email best practices
The tester provides actionable recommendations to help you optimize your subject lines for both open rates and deliverability.
Related Free Tools
Improve your email copy and deliverability with these related tools:
Subject Line Tester FAQs
Automate Subject Line Testing in Every Campaign
Get automatic subject line testing and A/B testing for all your email campaigns with SuperSend. Test multiple subject lines and optimize for the highest open rates automatically.