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Split-test a ChatGPT coupon email against a copywriter

WorkedEvidence: Article or interviewPosted Last checked

ChatGPT's coupon email tied a copywriter's in John Grimshaw's split test: 6.5 vs 6.3 clicks and $4.66k vs $4.7k.

How to use this

  1. Tap Copy prompt.
  2. Open ChatGPT.
  3. Paste it into the message box.
  4. Send it, then read the answer before acting on it.
New to this? What's a prompt?

A prompt is the message you send to the AI tool. Copy the one on this page, put your own details where it asks, and read the answer before you act on it.

Prompt

Original prompt

The prompt as the person shared it in the source.

What the prompt labels mean

These are the person's own words, as shared in the source.

Write me a marketing email, including a subject line and email body from the brand BOOM! by Cindy Joseph. The email is for people who just signed up for a 10% off coupon. They are expecting this coupon and the email should reflect that.

The important details for this email are that the discount works for all our products, but it’s only available for 72 hours, so recipients need to act quickly to take advantage of this deal. Match the style and tone from this website (boombycindyjoseph.com).

The email body should be between 100 and 200 words, and include at least three links to the website. Assume that this is the first email this person is receiving from Boom by cindy Joseph and that they are already signed up for the newsletter.

Additionally, describe an image that should be included in the email which should entice potential buyers.

Try this in:

Sends the Original prompt shown above. ChatGPT and Grok open with it filled in, and ChatGPT may send it straight away. Gemini and Claude open empty, so we copy the prompt for you to paste. Every button also copies it.

Opens in a new tab. We don't see what you send.

These links are only a shortcut. We're not affiliated with OpenAI, Google, Anthropic or xAI, and your results may not match the source.

Optional stronger version

Our rewrite with extra checks. The poster didn't test it.

Before you start, ask me 1–3 short questions about the details below and wait for my answers. Once I've answered, confirm the plan in one line and run the whole task start to finish.

Goal: Write a coupon welcome email in my brand's voice that I can split-test against my current version.

Questions to ask me first:
- What's the offer, and how long does it last?
- How would you describe the brand's tone, or can you paste a past email that performed well?
- Which version will this be tested against, and what metric decides the winner?

Inputs (fill in or confirm):
- Brand and product range: [BRAND / PRODUCTS]
- Offer and deadline: [OFFER / DEADLINE]
- Two or three past emails or website copy for tone: [SAMPLES]
- Word range for the body: [WORD RANGE]
- Links to include: [LINKS]
- Winning metric: [CLICKS / ORDERS / REVENUE]

Rules:
- Keep the body inside the word range; if I ask for 50 to 75 words, stay near 50.
- Put the offer and deadline in the first two lines.
- Match the tone of my samples; don't invent product claims, reviews or discounts.
- Write two subject lines, but tell me to use the same one in both test versions so only the body changes.
- Describe one image that fits the offer.

Checkpoint: Show me the draft and its word count before writing a second variation.

If you get stuck: If the tone samples conflict, ask me which one to follow.

Verify before you finish: Check the offer, deadline and links against my inputs.

Output: Subject lines, the email body with links marked, an image description and the word count.

Done when: I have an on-brand email ready for an A/B test with only the body changed.

AI tool

ChatGPT

Outcome

John Grimshaw of Smart Marketer split-tested a ChatGPT-written welcome email against a copywriter's version for the brand BOOM! by Cindy Joseph. The email delivered a 10% off coupon to new sign-ups, valid for 72 hours. The team tried six or seven prompt variations before settling on the winning one. Both emails used the same subject line. After 6,000 people, click rates were 6.5 versus 6.3, too close to call. The copywriter's version led early, $3,000 in revenue to $2,000, but the numbers evened out: about $4.7 thousand from 55 orders for the human email versus $4.66 thousand from 54 purchases for ChatGPT's. Grimshaw also noticed ChatGPT leaned toward longer copy, even when asked for 50 to 75 words.

Evidence: Article or interviewA newsletter, journalist or interview account of what happened.

Source

Posted
by John Grimshaw (Smart Marketer)
Last checked
Method:
How we verify

https://smartmarketer.com/chat-gpt-3-email-split-tests/

Context: This is the first of three tests in the article, run in 2023 with an older ChatGPT model. The results come from the team's email platform.

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