Email newsletter
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Drafts and designs a complete HTML email newsletter from a topic or content brief. Outputs paste-ready HTML for Loops, Mailchimp, Beehiiv, Resend, or any standard email platform. Includes subject line options and plain-text fallback. Trigger when a user says "write a newsletter", "draft an email newsletter", "create an HTML email", "design an email for my subscribers", or "write a newsletter about [topic]".
SKILL.md
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Email Newsletter
Draft and design a complete HTML email newsletter from a topic or content brief. Output is paste-ready for Loops, Mailchimp, Beehiiv, Resend, or any standard email platform.
Critical rule: Table-based HTML with inline styles only. No CSS classes, no flexbox, no grid, no <style> blocks. Every element gets style="" directly. This is not optional -- email clients strip everything else.
Step 1: Brief Intake
Need three things to start. If all three present in the message: skip to Step 2.
If any missing, ask exactly:
"To get started, I need three things:
- Topic -- what is this newsletter about?
- Audience -- who is reading? (role, company size, how they know you)
- Primary CTA -- what one action do you want readers to take?"
Wait for all three before continuing.
Step 2: Complete Intake
Ask all questions in one message, grouped by category. User can skip any -- defaults apply.
"A few questions before I draft -- answer what you know, skip the rest:
Content
- Length -- brief (300 words, punchy) / standard (500-700) / deep dive (800+ words)?
- Format -- editorial article / numbered breakdown / personal story / data report?
- Issue context -- one-time send / part of weekly series / monthly digest?
- CTA URL -- what's the actual link? (or I'll use a placeholder)
Brand 5. Company / brand name -- for header and footer 6. Tagline -- one-line description (optional, for footer) 7. City & country -- for footer (e.g. "San Francisco, US") 8. Primary brand color -- hex? (e.g. #856FE6) 9. Secondary accent -- keep default yellow-green (#D8F90A) / use brand color / something else?
Design 10. Background -- dark (editorial/SaaS) / light (clean/corporate) / custom hex? 11. Display font -- editorial serif (Instrument Serif) / clean modern sans / system fonts only? 12. Button style -- pill (very rounded) / softly rounded / sharp corners? 13. Visual style -- editorial / technical+data / warm+founder / bold+campaign?
Platform & Technical 14. Platform -- Loops / Mailchimp / Beehiiv / Resend / other? 15. Tone -- educational / conversational / bold+direct / formal / playful? 16. Personalization -- none / first name / first name + company? 17. Subject line -- have one / want 3 options? 18. Secondary sections -- sponsor block / product callout / event / quick links / none? 19. Plain-text version -- yes (recommended) / no?"
Defaults if skipped:
| Question | Default |
|---|---|
| Length | standard (500-700 words) |
| Format | editorial article |
| Issue context | one-time send |
| CTA URL | [CTA_URL] placeholder |
| Company name | [YOUR BRAND] placeholder |
| Tagline | none |
| City & country | [CITY, COUNTRY] placeholder |
| Brand color | none (use #D8F90A for all accents) |
| Secondary accent | #D8F90A (yellow-green default) |
| Background | dark |
| Display font | Instrument Serif (editorial serif) |
| Button style | pill |
| Visual style | editorial |
| Platform | generic |
| Tone | conversational |
| Personalization | none |
| Subject line | generate 3 options |
| Secondary sections | none |
| Plain-text | yes |
Step 2.5: Design Direction (internal -- not shown to user)
From Step 2 answers, determine:
- Visual character (from question 13, or inferred from tone + format if skipped)
- ONE unmissable element -- identify before Step 3
- Template path (see Step 5)
Character defaults if question 13 skipped:
- Educational / formal tone: Editorial
- Metrics-heavy content (stats, benchmarks, reports): Technical/data-forward
- Product launches, events, campaigns: Bold/campaign
Never ask the user for design direction separately -- derive it from their answers.
Step 3: Structure Design
Read references/html-email-guide.md for layout rules before choosing sections.
Based on topic + audience + CTA + secondary sections requested, select sections from this library:
| Section | Include when |
|---|---|
| header | Always -- logo placeholder + issue number or date |
| hero | Always -- big headline + 1-2 sentence hook |
| intro | Conversational or educational tone -- short personal note |
| main-content | Primary article or insight (text-heavy) |
| stat-callout | There is a compelling stat, quote, or data point |
| secondary-section | Secondary CTA was requested |
| product-cta | Brand context present and soft product plug fits |
| sponsor-block | Sponsor section was requested |
| quick-links | Curated links section was requested |
| footer | Always -- unsubscribe link + company name |
Output the chosen structure as a numbered list with one-line purpose per section:
Proposed structure:
1. Header -- logo + Issue #1 / [date]
2. Hero -- headline + hook paragraph
3. Intro -- short personal framing
4. Main Content -- [topic] breakdown
5. Stat Callout -- key data point from the story
6. CTA -- [cta text]
7. Footer -- unsubscribe + company
Does this structure work, or should I adjust any sections?
Wait for confirmation before Step 4.
Step 4: Content Draft
Write copy for each section in sequence. No HTML yet -- clean prose only.
Rules per section:
- Header: Issue number + date. No copy needed.
- Hero headline: 8 words max, outcome-focused, no starting with "I/We/Our"
- Hero hook: 1-2 sentences, problem or curiosity gap, pulls reader in
- Intro: 2-3 sentences, personal or contextual, not corporate-speak, contractions OK
- Main content: 250-400 words, scannable -- use bold phrases for key points, short paragraphs (1-3 lines), no walls of text, no bullet overload
- Stat callout: One stat or quote, 20 words max, punchy
- Product CTA: 2-3 sentences, value-forward, not "Check out our product" -- tell them what changes for them
- CTA button text: 3-5 words, action verb + benefit ("Read the full breakdown", "Save my seat", "Get the guide")
- Footer: Unsubscribe link placeholder + company name
Read references/subject-line-formulas.md then write 3 subject line options (if subject line not provided by user):
- Option A: Curiosity gap formula
- Option B: Direct benefit formula
- Option C: Number/list formula
Do not use em dashes. Do not use: "powerful", "seamless", "game-changing", "leverage", "innovative", "unlock", "transform", "elevate", "cutting-edge", "robust".
Step 5: HTML Generation
Read references/design-system.md and references/html-email-guide.md before generating HTML.
Template or custom -- decide based on Step 2 answers:
Use templates/dark-newsletter.html as base when ALL of:
- background = dark (or not specified)
- display font = Instrument Serif (or not specified)
- no custom background hex provided
Use templates/light-newsletter.html as base when ALL of:
- background = light OR tone = formal
- display font = Instrument Serif (or not specified)
- no custom background hex provided
Generate custom HTML from scratch when ANY of:
- custom background hex provided (not dark, not white)
- display font = modern sans or system fonts only
- combination of answers produces a design neither template serves
For custom generation: use references/design-system.md Custom Generation Guide as the full token spec. Apply user's background/font/button/accent choices throughout.
Then (for template path):
- Select only the sections needed from the template (based on Step 3 structure)
- Fill in all
[PLACEHOLDER]values with content from Step 4 - Apply brand color substitution (see below)
- Verify all
[UNSUBSCRIBE_URL]placeholders are still present (platform tuning happens in Step 6)
Brand color substitution rules:
If brand_color is provided:
- Replace brand strip
bgcolor(#D8F90Ain theheight:2pxrow) with brand_color - Replace stat callout left border color with brand_color
- Replace category label color with brand_color
- If brand_color luminance is high (yellows, greens, oranges -- most neons): replace step badge
#D8F90Awith brand_color too - If brand_color luminance is low (dark navy, forest, charcoal): keep step badges and CTA button as
#D8F90A, only use brand_color for strip + stat border
If brand_color is NOT provided: keep all #D8F90A values as-is.
Content substitution rules (from Step 2 answers):
- If
company_nameprovided: replace all[YOUR BRAND]and[COMPANY NAME]placeholders - If
city_countryprovided: replace[CITY, COUNTRY]placeholder - If
taglineprovided: add as subtitle line in footer after company name - If
cta_urlprovided: replace all[CTA_URL]placeholders with actual URL - If
personalization = first_name: add platform-appropriate first name variable to hero greeting -- e.g.Hey %%first_name%%,on Beehiiv,Hey {{first_name}},on Loops,Hey *|FNAME|*,on Mailchimp - If
personalization = first_name + company: add both variables where contextually appropriate
Brand color visual tension check (on dark email):
Does the brand color visually pop on #111111? Test mentally: would it be visible as a 2px strip?
- High-saturation colors (purples, blues, teals, pinks, yellows, oranges, greens): YES -- use for strip + stat border + category label
- Low-saturation / near-neutral (warm greys, beige, off-white): strip only; category label reverts to
#555555 - Near-black (very dark navy, forest, charcoal below ~
#2A2A2A): skip brand_color for ALL accent uses, fall back to#D8F90Afor every element
Accent discipline rule: brand_color appears in AT MOST 3 places: brand strip, stat border, category label. Never in body copy, headlines, button backgrounds, or section backgrounds. Over-branding kills the premium feel.
CTA button text color:
- On
#D8F90Abutton background: always use#0A0A0Atext (it's a light color) - On
#111111button background (inside yellow callout card): always use#F2F2F2text - On brand_color button: use
#0A0A0Aif brand is light,#FFFFFFif brand is dark
Required on every <td> with a background color:
Both the bgcolor= HTML attribute AND the inline background-color: style. Example:
<td bgcolor="#D8F90A" style="background-color:#D8F90A;">
The attribute handles Outlook. The style handles everything else. Never use just one.
Design excellence (frontend-design principles, email-adapted):
Email's table constraints don't limit design ambition. Push within them:
-
Typography to its extreme: 4-5 word headlines = 60px,
-0.04emtracking. 6-7 word headlines = 56px,-0.03em. 8 words = 48px. Never size down for safety -- the headline is a poster, not a label. Instrument Serif italic on stat quotes adds literary weight no other element can match. -
Density contrast as craft signal: Hero = maximum open space (64px top). Body paragraphs = tight and dense. CTA callout card = maximum open space again (64px). Open → tight → open is the rhythm that reads as intentional design, not template output.
-
Background depth via section alternation (all email-safe):
- Header:
#0A0A0A - Hero:
#111111 - Stat callout outer:
#111111, inner elevated card:#1A1A1A - Body paragraphs:
#161616(subtle elevation creates depth without color) - Step cards:
#111111(contrast with body) - CTA callout card:
#D8F90A(the ONLY bright element -- never dilute) - Footer:
#080808
- Header:
-
Accent scarcity = luxury: One yellow callout card in a sea of dark reads premium. Yellow appearing in six places reads cheap. The CTA card's power comes entirely from being the single bright element in a dark email.
-
Unforgettable test: Before saving, state in one sentence what a reader would describe to a colleague 3 hours later. If it's vague ("it was dark and clean") -- the visual anchor isn't strong enough. Make it specific ("the yellow card with the big serif headline").
-
Stat callout as editorial pull quote: 4px left border (not 3px). 26px italic Instrument Serif on the quote text. 32px inner padding. This is the closest an email gets to a magazine pull quote. Treat it like one.
Step 6: Platform Tuning
Read references/platform-compat.md and apply platform-specific adjustments:
| Platform | Action |
|---|---|
| Loops | Replace [UNSUBSCRIBE_URL] with {{unsubscribe_url}}. Replace [FIRST_NAME] refs with {{first_name}} |
| Mailchimp | Replace [UNSUBSCRIBE_URL] with *|UNSUB|*. Add mc:edit="[section-name]" to editable <td> blocks |
| Beehiiv | Replace [UNSUBSCRIBE_URL] with %%unsubscribe_url%%. Replace [FIRST_NAME] with %%first_name%% |
| Resend | Replace [UNSUBSCRIBE_URL] with {unsubscribeUrl}. Note: React Email .tsx output available on request |
| Generic/Other | Keep [UNSUBSCRIBE_URL] as placeholder with comment: <!-- Replace with your unsubscribe link --> |
Step 7: Self-QA
Check the generated HTML before output. Fix every issue found -- do not skip.
Rendering checks:
- All styles inline -- no
<style>blocks, noclass=attributes anywhere - All
<table>havecellpadding="0" cellspacing="0" border="0" - Images (if any) have
alt="",border="0",display:blockin style - Max-width 600px enforced on container table
- CTA button uses
<table>+<td>structure withbgcolor=attribute, not just<a>withdisplay:block - No
flexbox,grid,position:,float:, CSS variables (--var),min-height,max-heightin any inline style -
border-radiuson<td>only -- not on<table>or<a>(Outlook renders<td>radius) - Footer has unsubscribe link with platform-correct variable
Content checks:
- Hero headline is 8 words or fewer
- CTA button text is 3-5 words
- No em dashes (-- is fine, not --)
- No banned words: "powerful", "seamless", "game-changing", "leverage", "innovative", "unlock", "transform", "elevate", "cutting-edge", "robust"
- Plain-text version strips all HTML cleanly (if requested)
Design quality checks:
- ONE unmissable element from Step 2.5 is visually dominant -- not buried between equal-weight sections
- Typography hierarchy clear: H1 >> H2 >> body -- size contrast at least 2:1 between each level
- All spacing values from valid rhythm only: 8 / 16 / 20 / 24 / 32 / 40 / 52 / 64px -- no arbitrary values (18px, 22px, 30px, 45px, etc.)
- Brand color appears in 3 or fewer places -- count instances; if more, remove from lowest-priority element
- No email slop patterns -- check against the slop list in
references/design-system.md
If any check fails: fix inline, then re-run the checklist mentally.
Step 8: Subject Line Presentation
If 3 subject line options were generated, present them with a recommendation:
**Subject Line Options**
A. [subject] -- [formula used, best for what audience/context]
B. [subject] -- [formula used]
C. [subject] -- [formula used]
Recommendation: [A/B/C] -- [one sentence reason based on audience and tone]
If user provided their own subject line, skip this step.
Step 9: Save Files + Present Summary
Save the HTML to a file first -- do not dump it in the chat.
mkdir -p docs/newsletters
Write the full HTML to:
docs/newsletters/[topic-slug]-[YYYY-MM-DD].html
Where [topic-slug] is the topic lowercased with spaces replaced by hyphens (e.g. "AI B2B Sales" → ai-b2b-sales).
If a plain-text version was requested, also write it to:
docs/newsletters/[topic-slug]-[YYYY-MM-DD].txt
Then present this summary in the chat (no HTML code fence):
## Newsletter: [topic slug]
Date: [today's date] | Platform: [platform] | Tone: [tone]
Saved to: docs/newsletters/[topic-slug]-[YYYY-MM-DD].html
---
### Subject Lines
A. [subject A] -- [formula]
B. [subject B] -- [formula]
C. [subject C] -- [formula]
Recommended: [letter] -- [one-sentence reason]
---
### Send Checklist
- [ ] Replace [CTA_URL] with your actual link
- [ ] Replace [COMPANY NAME] and [CITY, COUNTRY] in footer
- [ ] Replace [YOUR BRAND] in header with your brand name (or swap in a logo image)
- [ ] Verify unsubscribe variable works in [platform]
- [ ] Send a test email to yourself before launching
Do not print the HTML in the chat. The file path tells the user where to find it.
Section Reference
| Section | Purpose |
|---|---|
| header | Logo + issue number or date |
| hero | Big headline + 1-2 sentence hook |
| intro | Short personal note or context |
| main-content | Primary article or insight (text-heavy) |
| image-block | Full-width image + caption |
| stat-callout | Highlighted stat or quote in a box |
| secondary-section | Second story or feature |
| product-cta | Soft product plug or feature highlight |
| sponsor-block | Sponsored content (clearly labeled) |
| quick-links | Curated links section (3-5 items) |
| footer | Unsubscribe link, company info, legal |
Output Formats (on request)
- Standard HTML (default): inline-styled, table-based, works everywhere
- React Email:
.tsxcomponent output -- request explicitly, good for Resend + dev teams - Plain text: stripped fallback always included unless user opts out