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email-subject-line-optimizer — Claude Code skill: A/B test email

This skill writes subject line variants from copywriting frameworks, predicts open rates and suggests what to A/B test next.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓
npx skills add OneWave-AI/claude-skills --skill email-subject-line-optimizer -a claude-code
Open on GitHub

What email-subject-line-optimizer does

The skill turns your agent into an email marketing assistant: it generates subject line options, predicts open rates from past performance and lays out an A/B testing plan. Output arrives as a markdown block with a results section and next steps.

Inside there is just a SKILL.md with instructions. The agent leans on copywriting frameworks and asks you for campaign context. No scripts run, no external service is called, so no API key is involved. Without your historical open-rate numbers the prediction rests on general reasoning, which is a good reason to keep last quarter's stats nearby.

Install it with npx skills add in Claude, Codex, Cursor, Gemini CLI or OpenCode; GitHub Copilot uses a separate gh skill install command.

What it helps with

  • draft five subject lines for a product launch email
  • predict which subject line gets more opens
  • build an A/B test plan for next week's campaign
  • rewrite a flat subject line using a copywriting framework
  • explain to the team why a subject line should work

Example prompts for the agent

  • Help me write five subject lines for our new pricing announcement
  • Predict open rates for these three subject lines from our past campaigns
  • Draft an A/B test plan for the webinar invite subject lines

How to install email-subject-line-optimizer

1Skills CLI (Vercel)

npx skills add OneWave-AI/claude-skills --skill email-subject-line-optimizer -a claude-code

2Manually: put the files in place

~/.claude/skills/email-subject-line-optimizer/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/email-subject-line-optimizer/

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about email-subject-line-optimizer

How do I install email-subject-line-optimizer in Claude?

Run npx skills add OneWave-AI/claude-skills --skill email-subject-line-optimizer -a claude-code. The skill lands in ~/.claude/skills/email-subject-line-optimizer/SKILL.md.

What does email-subject-line-optimizer do?

It generates subject line variants from copywriting frameworks, predicts open rates and returns A/B testing recommendations.

Does the skill need an API key?

No. It is an instruction file for the agent and calls no external services.

Source text

SKILL.md · MIT
---
name: email-subject-line-optimizer
description: A/B test subject line variations using proven copywriting frameworks. Predict open rates based on historical performance.
---

# 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

```markdown
# 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

Remember: Focus on delivering value quickly and clearly!

© OneWave-AI · MIT · OneWave-AI/claude-skills

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