• Moodboard
  • Posts
  • Increase your email open rates with this prompt 📬

Increase your email open rates with this prompt 📬

Generate 8 high-performing subject line options for any email in seconds

Author

Ryan Carr
September 25, 2025

Hello everybody, welcome back to Moodboard 🌴

Our team at Tailwind has sent thousands of newsletters over the past three years. 

Want to know the most painful lesson I've learned?

You can spend 6 hours crafting the perfect email (great topic, valuable insights, jokes that you hope people actually laugh at) and watch it die in the inbox because your subject line doesn’t cut it.

Today, I'm sharing a prompt I built to fix this problem. 

It analyzes your content and generates 8 subject line options using different psychological triggers that get those precious emails opened.

Let's try it out👇

The Prompt

Here's the complete prompt to copy/paste into Claude or ChatGPT (along with the content of your email):

Subject Line Generator Prompt:

Content to Analyze: [Paste your newsletter/email content here]

Based on the content above, generate 8 distinct email subject lines that will maximize open rates. Priority: Create subject lines that are impossible to ignore—they should be bold, intriguing, or unexpected rather than safe and predictable.

Your Task:

Analyze the content to identify:

  • The primary value proposition or benefit to the reader

  • The most intriguing or surprising element

  • Any data points, statistics, or specific outcomes mentioned

  • The emotional hook or pain point being addressed

  • The target audience and their likely interests

Create 8 subject lines using different proven approaches:

  1. Curiosity Gap: Create intrigue without giving everything away

  2. Benefit-Focused: Highlight what the reader will gain

  3. Urgency/Scarcity: Only if genuinely time-sensitive in the content

  4. Question-Based: Pose a compelling question the content answers

  5. Specific & Tangible: Use only actual numbers, data, or outcomes directly quoted in the content—never invent or extrapolate

  6. Contrarian/Unexpected: Challenge common assumptions

  7. Story/Personal: Lead with a narrative hook

  8. Direct/Bold Statement: Make a strong claim the content supports

Subject Line Guidelines:

  • Keep under 50 characters when possible (9 words maximum)

  • Avoid spam trigger words (FREE, GUARANTEED, ACT NOW)

  • Use power words that evoke emotion or action

  • Choose unexpected angles, contrarian views, or provocative statements

  • Use conversational language that feels human, not corporate

  • Never manufacture false urgency—only use time-sensitive language if the content actually contains deadlines or time-bound information

  • Consider starting with natural action verbs (Stop, Start, Try, Steal, Ditch, Skip, etc.) but avoid overused AI-isms like "Unlock," "Transform," "Elevate," or "Unleash"

  • Be intriguing but not vague—readers should understand the topic/benefit even if they don't know all the details. The subject line should clearly signal what value or topic the email contains while still creating curiosity about the specifics

Output Format: For each subject line, provide:

  • The subject line

  • Strategy used

  • Why this angle would appeal to the target audience

The Output

When you run this prompt, you'll get something like the following:

Each subject line option attacks the task from a different angle. 

Maybe the curiosity gap approach feels right for your audience for this particular piece of content. Or perhaps the data-driven subject line matches an analytical tone you’re going for.

Some strategies will work better than others, but the important thing is that we have some options to choose from.

Why I Recommend You “Prompt for Options”

A lot of AI image-generation/video-generation will give you options as a default. 

For example, Midjourney gives you four image variations to choose from. Google’s Veo model generates multiple video variations per prompt (based on your appetite for token-spend).

But when you ask a tool like Claude or ChatGPT for text content, you only get one take.

From there, it’s on you to go with that first draft, ask for edits, or, in some cases, just start over.

That's a problem when you're creating something as crucial as a subject line. You need options to choose from, combine, and iterate on.

This prompt forces Claude/ChatGPT to think through your content from 8 different angles. Even if somehow none of them are “send-worthy” as-is, I guarantee 3-4 will spark ideas you can refine into something great!

Suffice it to say, “prompting for options” is a principle I’ve been leaning into more and more when creating workflows. It works for everything from landing pages to LinkedIn posts.

Huge time saver, and I end up happier with the final product.

Give It a Shot

Next time you're about to hit send on an email, run your content through this prompt first.

Test a few variations. Maybe A/B test your favorites if your platform supports it.

And, as always, let me know how it goes for you!

Until next week,

Ryan