Free AI prompt · ChatGPT · Claude · Gemini

Write cold email subject lines that look human

Use after you have a campaign brief. You get 15 short subject lines that look like they came from a person, not a marketing team, grouped by style, with the three best picked out for testing.

Task: writing cold email subject linesBest in: ChatGPTFormat: single promptPack: Cold email sequence that gets replies

What you'll fill in

  • [campaign brief] The brief from prompt 1 e.g. “Segment: owners of 8-30 person architecture firms hiring now...”
  • [first email summary] One line on what the first email says (or leave as "not written yet") e.g. “Noticed they are hiring; offer a free books health check”

Copy the prompt

The prompt
You are a cold email specialist. In cold outreach, subject lines that look like internal or personal emails tend to do better than ones that look like marketing. They are short, lowercase or sentence case, and specific.

Campaign brief:
[campaign brief]

What the first email says: [first email summary]

Write 15 subject lines, grouped into 5 styles with 3 each:
1. Plain and specific (what the email is about, 2-4 words)
2. Trigger-based (reference the reason I'm emailing now, e.g. their hiring)
3. Question (a short question the recipient would actually want answered)
4. Name or company placeholder (use {first_name} or {company} as merge fields)
5. Peer-to-peer (sounds like a note from someone in their industry)

Rules:
- Max 6 words, ideally 2-4.
- No ALL CAPS, exclamation marks, emojis, "quick question", "re:" or "fwd:" tricks, or anything that implies a previous conversation that did not happen.
- Avoid words that look like spam or sales pitches (free, guarantee, discount, act now).
- Every subject line must be honestly supported by the email body.

Then pick the 3 strongest for an A/B test and say in one line each what you would expect to learn from testing it.

How to use it

  1. Open a new chat in ChatGPT (the others work too).
  2. Paste the prompt and replace every [bracket] with your details.
  3. Review the output, check any facts, and edit to taste.

Why ChatGPT: ChatGPT is fast at generating many short variations; any model works well for this one.

Tips

  • Merge fields like {first_name} must match the exact syntax of your sending tool. Check before you load them.
  • Test subject lines against each other with the same email body, or you will not know which change made the difference.
  • Opens are a rough signal at best because privacy features distort them. Judge winners by replies.

Example output

1. Plain and specific - books health check - project profitability - your bookkeeping 2. Trigger-based - saw the project manager role - hiring and payroll - before your next hire 3. Question - who does your books? - clean books for the bank? - sunday bookkeeping? 4. Name or company - {company} books - idea for {company} - {first_name}, 20 minutes? 5. Peer-to-peer - from a fellow firm owner's bookkeeper - architecture firm books - what other firms do at tax time Top 3 for testing - "saw the project manager role" - tests whether referencing the trigger makes the email feel relevant. - "who does your books?" - tests a direct question against a statement. - "{company} books" - tests whether personalization alone helps.

FAQ

Does this prompt work in ChatGPT, Claude and Gemini?

Yes. It is plain-language and written to work in all three. Best fit: ChatGPT. ChatGPT is fast at generating many short variations; any model works well for this one.

What do I need to fill in?

Replace each bracket with your own details: [campaign brief], [first email summary]. The more specific your input, the more useful the result.

Is this prompt free?

Yes. Copy it above and use it as often as you like. It is one of the free samples from the Cold email sequence that gets replies pack.

Will I get the same result as the example?

No. The example was made for a fictional business to show the shape and quality of the output. Your result depends on your input and the model, so review and edit before you use it.

Do I need a paid AI plan?

Usually not. Free plans handle most prompts. Paid plans help when you paste in long documents or run a long multi-step sequence in one chat.

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