Copywriting & Conversion5.0 · 0 ratings

Newsletter Subject Line Lab

Generates and rates subject-line variations across psychological angles, optimized for opens without clickbait.

Role-BasedSelf-CritiqueStructured-Output

Prompt

ROLE: You are an email copywriter obsessed with open rates who never resorts to clickbait that burns trust.

CONTEXT:
- Newsletter/topic: [NEWSLETTER].
- This issue's core idea: [ISSUE_TOPIC].
- Audience & their relationship to us: [AUDIENCE / RELATIONSHIP].
- Voice: [VOICE]. Send context: [BROADCAST / AUTOMATION].

TASK:
1. Write 12 subject lines spanning these angles: curiosity gap, specific number, contrarian, benefit, urgency, personal/story, question, and 'how to.'
2. Pair each with matching preview text that extends (not repeats) the subject.
3. Score each 1-5 on Curiosity, Clarity, and Trust; flag any that over-promise.
4. Recommend the top 3 to A/B test and explain why.

OUTPUT FORMAT: A table — Subject | Preview | Angle | Curiosity | Clarity | Trust | Notes — then a 'Test these 3' recommendation.

CONSTRAINTS: The email body must be able to deliver on every subject — no bait-and-switch. Keep subjects under 50 characters where possible. Vary length and structure so the inbox doesn't look monotone. Trust score below 3 = reject and rewrite.

How to use this prompt

  1. 1

    Copy the prompt above and paste it into ChatGPT, Claude, or Gemini — or open it in the visual Studio to edit each part on a canvas and run it with your own key.

  2. 2

    Replace any bracketed placeholders with your specifics. The more concrete your context and constraints, the sharper the result — see the 5-part prompt structure.

  3. 3

    Run it, then refine. Ask the model to critique and improve its own answer with self-critique prompting.

Techniques in this prompt

Role-Based

Assigns the model an expert persona so it adopts the right vocabulary, depth, and standards for the task.

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Self-Critique

Has the model critique its own draft against criteria, then revise — raising quality in a single pass.

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Structured Output

Pins the response to a defined structure so it drops straight into your workflow.

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Recommended models

claudegpt-4ogemini

Build on this prompt

Open it in the visual Studio to wire it into a full workflow with your own API key — or learn the craft behind prompts like this.

Open in Studio How to prompt AI correctly

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