Generate 10 subject-line variations for our [campaign — e.g., Mother's Day] email — [product/collection] at [discount]% off.
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Generate 10 subject-line variations for our Mother's Day email. The email features our hydrating serum collection at 20% off. Show predicted open-rate tier (high / mid / low) and a one-line rationale for each.
- 10 distinct variations covering different psychological angles.
- Predicted open-rate tier (high / mid / low).
- One-line rationale per subject line.
- Grounded in your past email performance.
What you're trying to do
Subject lines are the single biggest lever on email performance — a 5% lift in open rate compounds across every email. Most teams write one subject line and ship. Generating 10 variations, picking the best, and even A/B-testing the top 2 is a low-cost way to materially lift email ROI.
Things to watch out for
- Voice consistency — Fudge handles this: variations match your brand voice, don't drift into clickbait.
- Spam triggers — Fudge avoids known spam-flagging language.
- Length — Fudge optimizes for mobile preview (35–50 chars).
- A/B test — Fudge can split the top 2 in Klaviyo automatically.
How Fudge does it
Fudge analyzes your store data, recent traffic and orders, and brand context, then delivers the plan as a structured report. No theme changes — pure strategy. Each recommendation comes with the exact prompt to ship it as a follow-up if you want to act on it.
When subject line A/B testing matters more than the email
Subject lines determine whether emails get opened. A 20% open rate vs. 30% open rate is a 50% relative lift on the email — bigger than most other optimizations you could run. The generator produces 10 subject line variations per email with predicted open-rate tiers and rationale, ready for A/B testing.
When this is worth doing
Run the generator before any meaningful email campaign — holiday push, product launch, sale announcement. Skip for routine transactional emails where subject lines are functional.
What makes a great generator pass
- 10 variations — enough breadth without choice paralysis.
- Predicted open-rate tier per variation — high / mid / low. Sets expectations.
- One-line rationale per variation — explains why each angle.
- Brand voice calibrated — sounds like you.
- Different angle types — curiosity, urgency, benefit, social proof, question. Coverage of categories.
Common mistakes to avoid
The biggest mistake is testing 10 variations at once. Test 2 head-to-head, then test the winner against the next contender. Brackets work better than bulk tests.
The second mistake is over-optimizing for opens. Subject lines that pull opens but disappoint on body don’t compound. Match subject promise to email content.
Pair this with email funnel audit and campaign brainstorm — three tools for email-led campaign performance.