A Score
36
B Score
42
Recommended
Subject B
How it works
Email open rates depend primarily on the subject line — and subject lines that trigger spam filters, feel generic, or fail to communicate value are opened by fewer than 15% of recipients. The Email Subject Line Tester scores your subject line on length, spam trigger words, personalisation tokens, power words, and mobile preview — giving you an overall score and specific improvement suggestions.
Scoring dimensions: - Length (0–20 points): optimal range is 35–50 characters. Under 20 characters provides insufficient context; over 60 characters is cut off on mobile. - Spam trigger words (0–20 points): words like "FREE", "Act now", "Congratulations", "No cost", and excessive punctuation trigger spam filters in Gmail, Outlook, and Apple Mail. Each trigger word found deducts points. - Power words (0–20 points): words with high emotional or curiosity-driving impact: "secret", "mistake", "new", "you", "today", "proven", "exactly", "never" - Personalisation (0–20 points): subject lines with first_name tokens or personalised content signals average 26% higher open rates - Preview text complement (0–20 points): the preview text (preheader) should complete the subject line thought — together they should tell a complete story
How to use: 1. Enter your subject line. 2. Optionally enter your preview text. 3. The score and suggestions appear instantly. 4. Edit and watch your score improve in real time.
Privacy: subject line analysis runs in the browser. No email data is transmitted.
Frequently Asked Questions
- Average email open rates vary significantly by industry. Overall averages across industries are 20–25% open rate. High-performing rates: government/civic (40%+), nonprofits (28%), education (28%). Lower-performing: e-commerce (18–20%), real estate (22%). Creator newsletters with engaged audiences typically achieve 35–50% open rates. If your open rate is below 15%, subject line quality is likely a contributing factor alongside list health.
- The word 'FREE' in all caps (and even in mixed case) is a top spam filter trigger across Gmail, Outlook, and Apple Mail. Spam filters assign negative scores to messages containing it, increasing the probability of landing in the spam folder before the open rate is even measured. Additionally, recipients who do see it have been conditioned to associate it with low-quality promotional email, reducing trust. Rewrite 'FREE guide' as 'The [guide name]' or 'Your [topic] checklist' instead.
- Preview text is the 40–100 characters shown after the subject line in the inbox view. A/B tests consistently show that subject lines paired with a complementary preheader (one that completes the subject's thought or adds urgency) achieve 10–20% higher open rates than subject lines with no preheader or an auto-generated preheader (which defaults to the first line of the email body). Treat the subject + preheader as a two-line unit, not independently.
- Emojis in subject lines increase open rates by approximately 5–10% on average — but with significant variance by audience and industry. B2C audiences (especially younger demographics) respond positively; B2B audiences are more neutral or slightly negative. Test with your specific list. Single strategic emoji placement at the start or end of the subject line outperforms emoji-heavy subject lines ('🔥🔥🔥 HUGE SALE 🔥🔥🔥'), which trigger spam filters.