Purpose
Produce a deep set of subject line and preview text pairs for one specific email — organized by tone, checked for mobile truncation, and packaged with ready-to-run A/B test matchups — so email marketers stop guessing at open rates and always ship the strongest variant. Solves the problem of one-and-done subject lines by generating enough tested options to test intelligently.
When to Use
Invoke this skill when the user asks to:
- Write subject lines for a specific email or campaign
- Generate subject line options in different tones (clever, direct, curiosity-driven)
- Create A/B test variants for an email send
- Improve open rates on a newsletter, promo, or automated flow
- Write subject line + preview text pairs for a consumer brand send
Inputs Required
Before starting, collect:
- Email purpose: What this email is (promo, newsletter, welcome, cart abandon, re-engagement, announcement)
- Core message: The one thing the reader should take away or do
- Offer/hook: The specific offer, discount, news, or value inside (if any)
- Audience: Who receives this — segment, relationship stage, familiarity with the brand
- Brand voice: 2–4 adjectives describing the brand's tone
- Send context: Timing, urgency, whether it's part of a sequence
- Emoji policy: Allowed / avoid / brand-standard set
If brand voice or emoji policy is missing, default to a warm consumer tone with no emojis and note the assumption.
Instructions
Generate 30 Subject Line + Preview Text Pairs Across 6 Tonal Strategies
For every pair, output:
- Subject line — filled in with the actual offer/message, never a template with brackets
- Preview text — 35–90 characters that extends the subject rather than repeating it
- Chars: subject character count
- Trigger: the psychological driver being activated
- Mobile note: flag if the subject exceeds ~41 characters (truncates on most mobile clients)
Subject line best practices applied throughout:
- Front-load the most important words (first 3–4 words survive truncation)
- Preview text must complete a thought the subject started — not duplicate it
- Vary lengths deliberately: some short (under 30 chars), some mid (30–50)
Strategy 1 — Direct/Clarity (6 pairs) State the value or offer plainly. No mystery. Best for promos and bottom-funnel sends where the reader already wants what's inside.
- Triggers: desire, clarity, self-interest
- Lead with the number, discount, or concrete outcome
- Example shapes: "[Offer] ends tonight" / "Your [benefit] is ready" / "[Number]% off, no code needed"
Strategy 2 — Curiosity-Driven (6 pairs) Open a loop the reader must click to close. The gap must feel resolvable and relevant — never clickbait that the email doesn't pay off.
- Triggers: curiosity, incompleteness, intrigue
- Do not reveal the answer in the subject; let preview text tease, not resolve
- Example shapes: "The one thing we changed..." / "You weren't supposed to see this yet" / "This surprised even us"
Strategy 3 — Clever/Playful (5 pairs) Wordplay, wit, or a light twist that rewards the reader for reading. Best when brand voice supports personality and the audience is warm.
- Triggers: delight, brand affinity, pattern interrupt
- Keep it decodable at a glance — cleverness that requires effort loses opens
- Never sacrifice clarity of the offer for a joke on a promo send
Strategy 4 — Urgency/Scarcity (5 pairs) Give a real reason to act now. Only use when genuine urgency exists — manufactured urgency erodes list trust and hurts long-term deliverability.
- Triggers: FOMO, loss aversion, deadline pressure
- Anchor to a specific time or quantity, not vague "hurry"
- Example shapes: "Ends at midnight" / "Only [N] left" / "Last call: [offer]"
Strategy 5 — Personal/Conversational (5 pairs) Sounds like a message from a person, not a brand broadcast. Best for newsletters, welcome flows, and re-engagement.
- Triggers: familiarity, relationship, curiosity
- Use lowercase or a first-person framing where brand voice allows
- Example shapes: "quick question for you" / "I wanted you to see this first" / "hey — did this reach you?"
Strategy 6 — Benefit-Stacked/Value (3 pairs) Pack a concrete, specific payoff into the subject. Clear outcome, no cleverness. Strong for content and educational sends.
- Triggers: aspiration, specificity, confidence
- Name the tangible result the reader gets by opening
- Example shapes: "[Result] in [timeframe]" / "How to [outcome] before [event]"
Build 3 A/B Test Matchups
Select the 6 strongest pairs and organize into 3 head-to-head tests, each isolating ONE variable so results are readable:
- Test 1 — Tone: Curiosity variant vs. Direct variant (same offer, same length band)
- Test 2 — Length: Short subject vs. longer descriptive subject (same tone)
- Test 3 — Framing: Benefit-forward vs. Urgency-forward
For each test, state:
- Variant A and Variant B (subject + preview)
- The variable being tested (everything else held constant)
- Hypothesis: which will likely win and why
- Winning metric: open rate at statistical significance (note minimum sample if list size is small)
Final Recommendation
Name the single subject line you'd send if only one were allowed, with a one-sentence rationale. Be opinionated.
Output Format
- Structure: 6 labeled tonal strategies with numbered pairs; each pair shows subject, preview, char count, trigger, mobile note; followed by 3 A/B test matchups and a final pick
- Length: 900–1,300 words
- Format: Scannable structured lists — not prose paragraphs
- Sections: 6 strategy lists → 3 A/B test matchups → Final recommendation
- Tone: Practical email specialist — decisive, benchmark-aware, no filler
Quality Checklist
Before delivering output, verify:
- [ ] All 30 pairs are present (count them; category counts are 6, 6, 5, 5, 5, 3)
- [ ] Every subject is filled in with the actual offer/message — zero bracket placeholders
- [ ] Every pair has a character count, trigger label, and mobile truncation flag
- [ ] Preview text extends the subject in every pair — never a duplicate of it
- [ ] All 3 A/B tests isolate exactly one variable, with everything else held constant
- [ ] A single final recommendation is made without hedging
Notes
- Preview text is the most-neglected open-rate lever — a strong subject paired with wasted preview text ("View this email in your browser") leaves opens on the table
- On promo sends, clarity almost always beats cleverness; save clever subjects for warm, engaged segments
- If the list is under ~2,000 recipients, note that A/B results may not reach significance and recommend testing the highest-conviction variant instead of splitting
- Respect the emoji policy strictly — an off-brand emoji can tank both opens and deliverability with spam filters
How to use this skill
This file is a Claude Code skill in Anthropic's standard format — markdown with YAML frontmatter at the top.
Installing in Claude Code:
~/.claude/skills/<folder-name>/SKILL.md— auto-loads in every session anywhere on your machine (recommended for skills you'll use across multiple projects)<your-project>/.claude/skills/<folder-name>/SKILL.md— auto-loads only when working in that project (recommended for project-specific skills)
Restart Claude Code or open a new session to register.
Using in Claude.ai, ChatGPT, Gemini, or other AI tools:
- Drag this file into a new chat, or copy and paste its contents
- Send your task or request as your next message — the AI will apply the skill where it fits
For Claude Code skill details: https://docs.anthropic.com/en/docs/claude-code/skills