You can write perfect email copy and still get ignored — if the subject line fails.
I spent 3 months testing AI-generated subject lines against my own handwritten ones. The result: AI-assisted subjects consistently outperform hand-written ones by 20–40% open rate, mainly because the AI never runs out of angles.
Here are 25 of the 97 email subject line prompts I now use, organized by goal. These aren't subject lines — they're prompt templates you feed to any AI to generate dozens of variations instantly.
Cold Outreach (getting a first response)
Prompt 1: "Write 10 cold email subject lines for a [job title] at a [industry] company. Goal: get them curious enough to open. No clickbait. Use specificity over hype."
Prompt 2: "Generate 8 subject lines that open with a mutual reference or shared context. Template: '[Name] → [Company] → you'. Make them feel warm, not salesy."
Prompt 3: "Write subject lines for cold outreach that reference a specific pain point in [industry]. Each line should imply you have a solution without stating it."
Follow-Up Sequences (when they went silent)
Prompt 4: "Create 6 follow-up subject lines that are direct without being passive-aggressive. Max 7 words each. Must not use 'checking in' or 'following up'."
Prompt 5: "Write 8 'last touch' subject lines for the final email in a sequence. Tone: confident, no desperation, clear this is the last one."
Prompt 6: "Generate subject lines for a re-engagement email sent 90 days after a prospect went cold. Should feel like a genuine reconnect, not a sales push."
Newsletter Growth (subscriber acquisition)
Prompt 7: "Write 10 subject lines for a lead magnet delivery email. The lead magnet is [describe it]. Make the subject feel like a gift, not a transaction."
Prompt 8: "Create subject lines for a welcome email sequence, emails 1-5. Each should set a different expectation about what the newsletter delivers."
Prompt 9: "Generate subject lines for an email asking readers to forward to someone who'd find it useful. Natural, not pushy."
Product Launches & Promotions
Prompt 10: "Write 12 subject lines for a product launch email. Mix urgency (deadline-based), curiosity (what is it?), and social proof (others are getting results)."
Prompt 11: "Create pre-launch teaser subject lines — 3-email sequence that builds anticipation without revealing the product until email 3."
Prompt 12: "Generate subject lines for a price increase announcement that frames it as a benefit to existing customers who act before the date."
Client Relationship Emails
Prompt 13: "Write subject lines for a monthly check-in email to retainer clients. Should feel personal, not templated. Reference their ongoing goals."
Prompt 14: "Create subject lines for a 'we just hit a milestone' celebration email to send to a client. Tone: shared win, not self-congratulatory."
Prompt 15: "Write subject lines for an upsell email to an existing client. Frame the offer as a natural next step, not a new sales pitch."
Re-Engagement Campaigns
Prompt 16: "Generate 8 subject lines for a win-back campaign for subscribers who haven't opened in 60+ days. Mix humor, directness, and value offers."
Prompt 17: "Write subject lines for a 'we changed, come back' email. Should acknowledge the subscriber's absence without guilt-tripping them."
Social Proof & Case Studies
Prompt 18: "Create subject lines that lead with a result. Format: '[Specific outcome] — here's what [person/company] did.' Make outcomes concrete and measurable."
Prompt 19: "Write 8 subject lines for a testimonial-led email. The testimonial is: [paste testimonial]. Extract the most compelling phrase and build the subject around it."
Authority & Thought Leadership
Prompt 20: "Generate subject lines for a 'contrarian take' email — something in your industry that most people get wrong. Tone: confident, slightly provocative."
Prompt 21: "Write subject lines for a personal story email that ties back to a business lesson. Should make the reader feel like they're getting insider access."
Prompt 22: "Create subject lines for a 'what I learned' email after a significant experience (conference, project, failure, client situation)."
Event & Webinar Promotion
Prompt 23: "Write subject lines for an event invitation email. Event: [describe it]. Mix urgency (limited spots), value (what they'll walk away with), and social context (who else is coming)."
Prompt 24: "Generate subject lines for a 'recording available' email post-event. Should entice people who missed it without making them feel bad."
Prompt 25: "Create subject lines for a last-chance reminder email, 4 hours before an event closes. Maximum urgency, minimum word count."
How I Use These
I keep these 97 prompts in a doc alongside my email calendar. Each week:
- Pick the email type I need (outreach, newsletter, promo)
- Run the prompt through Claude or GPT
- Get 8-12 variations in 30 seconds
- Test 2 of them in a split
My open rate went from ~22% to ~34% average in 3 months. The biggest win was the cold outreach prompts — specificity beats creativity every time.
The full pack has 97 prompts across every email type I've tested: cold, warm, follow-up, promo, re-engagement, transactional, and relationship. I built it because I was tired of staring at a blank subject line field.
EmailForge — 97 Email Marketing Prompts →
It's €19. If email is part of how you grow, it pays for itself the first week.
What's your go-to subject line formula? Drop it in the comments — I'll run it through the prompts and see what variations come out.
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