Email Subject Line Analyzer

Email Subject Analyzer

Evaluates email subject lines for length, spam trigger words, readability, and predicted open rate impact. Paste your subject line to get feedback before sending.

Key factors analyzed

• Length: ideal range is 30-50 characters; most email clients truncate at 60-80 characters on desktop, less on mobile
• Spam words: flags words commonly associated with spam filters (free, guarantee, act now, etc.)
• Personalization tokens: detects use of first name or dynamic fields like {{name}}
• Question format: questions tend to improve open rates by creating curiosity
• Capitalization: ALL CAPS increases spam score; title case vs. sentence case differences
• Numbers and symbols: specific numbers (Save 27%) outperform vague claims (Save more)

Subject line best practices

• Keep it under 50 characters to avoid truncation on mobile
• Place the most important word in the first 30 characters
• Avoid excessive punctuation and exclamation marks
• A/B test two versions for campaigns with 1000+ recipients
• Match the subject to the email body content; misleading subjects increase unsubscribe rates

Spam trigger words to avoid

Words like "Free", "Guaranteed", "Click here", "You've been selected", "No obligation", and excessive punctuation (!!!) are associated with spam filters in tools like SpamAssassin and Outlook's Junk filter.