Email subject lines
📖 3 min readUpdated 2026-04-19
Subject lines are your email's hook. Short, specific, personal wins.
Patterns that work
- Question
- Specific number / detail
- Curiosity gap
- Direct value promise
- Personal / conversational
Anti-patterns
- All caps
- Multiple exclamations
- Marketing buzzwords ('Don't miss!')
- Clickbait without payoff
Length
30-50 chars optimal. Mobile cuts off at ~30-40.
A/B test
Always test 2 variants. Small changes can swing open rate 5-20%.
What to do with this
- Write subject lines like a peer emailing a peer, "your Q3 numbers" beats "weekly newsletter #47"
- Keep subjects at 30-50 characters, longer gets truncated on mobile and loses punch
- Test 2-3 subject line variants per broadcast, the subject is where the biggest open-rate swings happen
- Avoid promotional trigger words (FREE, SALE, $) especially in all caps, they tank deliverability faster than open rate
- Use preview text deliberately, the preview line alongside subject is often what decides the open