## Contents

- Subject Line Formulas (25+)
- Curiosity
- Benefit-Driven
- Social Proof
- Urgency/Scarcity
- Personal/Conversational
- Number/List
- Subject Line Best Practices

## Subject Line Formulas (25+)

### Curiosity

1. `The [adjective] reason your [thing] isn't [desired outcome]`
2. `I was wrong about [topic]`
3. `The [thing] nobody talks about`
4. `What [impressive person/company] knows that you don't`
5. `Stop doing [common practice] (here's why)`

### Benefit-Driven

6. `How to [achieve outcome] in [timeframe]`
7. `[Number] ways to [benefit] without [pain]`
8. `The fastest way to [desired outcome]`
9. `Get [specific result] — no [common objection] required`
10. `Your [time period] plan for [outcome]`

### Social Proof

11. `How [customer] went from [before] to [after]`
12. `[Number] [people/companies] can't be wrong`
13. `"[Short testimonial quote]" — [Customer Name]`
14. `Why [respected company] switched to [Product]`

### Urgency/Scarcity

15. `[Offer] expires at midnight`
16. `Last chance: [specific benefit]`
17. `Only [X] spots left for [thing]`
18. `[Hours/Days] left to claim [offer]`

### Personal/Conversational

19. `Quick question about [their goal]`
20. `[Name], can I be honest with you?`
21. `This made me think of you`
22. `Re: your [product/goal]` (deception risk — only legitimate if it references a real prior thread; faking a reply to a conversation that never happened can violate CAN-SPAM's "not misleading" rule and torches trust. Prefer the honest variants.)
23. `I noticed you [action they took]` (only if you actually have that behavioral data — never fabricate an action the recipient didn't take)

> **Guardrail:** Subject lines must be truthful and not misleading (CAN-SPAM §5(a)(2), and a recurring trigger for spam complaints under Google/Yahoo's <0.3% threshold). Fake "Re:"/"Fwd:" prefixes, false urgency, and invented personalization ("I saw you did X") are the fastest way to tank sender reputation. Curiosity is fine; deception is not.

### Number/List

24. `[Number] [things] I wish I knew about [topic]`
25. `The [number]-minute fix for [problem]`
26. `[Number] mistakes killing your [metric]`
27. `[Number] tools for [outcome] (I use #[X])`

### Subject Line Best Practices

- **Length:** 30-50 characters (6-10 words) for best open rates
- **Mobile preview:** First 30 chars must hook — most people read on phones
- **Personalization:** [Name] in subject line lifts opens 10-20% (don't overuse)
- **Emojis:** One emoji can boost opens 5-10%. Two or more looks spammy
- **Avoid spam triggers:** FREE (all caps), !!!, $$$, "Act now", "Limited time"
- **A/B test:** Always test 2 subject lines. Send winner to remaining 80%

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