"Write a marketing email" — the prompt that returns filler, rewritten
Why a one-line marketing email prompt produces generic copy, and a reusable version with audience, offer, constraints and a ranking rule.
The prompt, as typed
Write a marketing email for our sale. Make it professional and persuasive.
What it leaves the model to guess
- What is on sale, for whom, and for how long
- The single action the email should drive
- Word count and whether there is a subject line
- What the brand never says
Graded before and after
Both versions below were scored by the same rubric the free prompt grader runs.
As typed
18/100 · grade F
| Clarity of context | 2 |
|---|---|
| Structure | 3 |
| Specificity | 2 |
| Reusability | 0 |
| Decision logic | 0 |
Rewritten
90/100 · grade A-
| Clarity of context | 5 +3 |
|---|---|
| Structure | 6 +3 |
| Specificity | 6 +4 |
| Reusability | 6 +6 |
| Decision logic | 5 +5 |
The rewritten prompt
Write a promotional email.
Audience: {{audience}}
Offer: {{offer}}
Deadline: {{deadline}}
Single desired action: {{cta}}
Output:
1. Three subject lines, max 45 characters each
2. Preview text, max 90 characters
3. Body of 120-160 words, one CTA, no sub-offers
Constraints: no exclamation marks, no "don't miss out", no countdown language
beyond stating the deadline once.
Rank the three subject lines by how clearly they state the offer, and give a
one-line reason for the top pick. Why the rewrite works
The original asked for "an email" and got one — but nothing in it was decided by you. The rewrite fixes the deliverable count, the character limits and the banned phrases, so two runs a month apart are comparable instead of merely both being emails.
Common questions
- Why does this prompt score badly?
- It scores 18 out of 100 (F) because it leaves the model to decide 4 things you already know: what is on sale, for whom, and for how long; the single action the email should drive; word count and whether there is a subject line; what the brand never says.
- Does a longer prompt always score higher?
- No. The rubric rewards named inputs, a fixed output format and an explicit rule for choosing between options. Extra prose without those adds length and no score.
- Will this rewritten prompt work in ChatGPT and Claude?
- Yes. It is plain text with placeholders you fill in before running, so nothing in it is specific to one model or vendor.