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Email Subject Line Optimizer

If you're sending marketing emails or newsletters, this gives you multiple subject line variations using established copywriting frameworks and estimates open rates based on historical patterns. You paste in your email context, and it generates A/B test candidates with predictions on which will perform better. The format is clean with copy-paste ready options and explanations for why each approach might work. Honestly most useful if you're doing regular sends and want to move faster than manually brainstorming five versions of the same hook. Saves the back-and-forth of "does this sound too salesy" conversations.

skills.sh installs
337
GitHub stars
422
last updated
Aug 21, 2026

Install

$ npx -y skills add onewave-ai/claude-skills --skill email-subject-line-optimizer --agent claude-code

Installs into .claude/skills of the current project.

Files

Email Subject Line Optimizer

A/B test subject line variations using proven copywriting frameworks. Predict open rates based on historical performance.

Instructions

You are an expert at email marketing and copywriting. Create high-performing subject lines, predict open rates, and provide A/B testing recommendations.

Output Format

# Email Subject Line Optimizer Output

**Generated**: {timestamp}

---

## Results

[Your formatted output here]

---

## Recommendations

[Actionable next steps]

Best Practices

  1. Be Specific: Focus on concrete, actionable outputs
  2. Use Templates: Provide copy-paste ready formats
  3. Include Examples: Show real-world usage
  4. Add Context: Explain why recommendations matter
  5. Stay Current: Use latest best practices for marketing

Common Use Cases

Trigger Phrases:

  • "Help me with [use case]"
  • "Generate [output type]"
  • "Create [deliverable]"

Example Request:

"[Sample user request here]"

Response Approach:

  1. Understand user's context and goals
  2. Generate comprehensive output
  3. Provide actionable recommendations
  4. Include examples and templates
  5. Suggest next steps

Sponsors

Details

Repository
github.com/onewave-ai/claude-skills
Categories
Testing & QA, Debugging, Marketing & SEO
First seen
Jun 3, 2026

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