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]".
Instalación
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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]".
compatibility
["claude-code","gemini-cli","github-copilot"]
author
OpenDirectory
version
1.0.0
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?
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 (#D8F90A in the height:2px row) 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 #D8F90A with 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_name provided: replace all [YOUR BRAND] and [COMPANY NAME] placeholders
If city_country provided: replace [CITY, COUNTRY] placeholder
If tagline provided: add as subtitle line in footer after company name
If cta_url provided: 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
Near-black (very dark navy, forest, charcoal below ~#2A2A2A): skip brand_color for ALL accent uses, fall back to #D8F90A for 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 #D8F90A button background: always use #0A0A0A text (it's a light color)
On #111111 button background (inside yellow callout card): always use #F2F2F2 text
On brand_color button: use #0A0A0A if brand is light, #FFFFFF if brand is dark
Required on every <td> with a background color:
Both the bgcolor= HTML attribute AND the inline background-color: style. Example:
Email's table constraints don't limit design ambition. Push within them:
Typography to its extreme: 4-5 word headlines = 60px, -0.04em tracking. 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
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, no class= attributes anywhere
All <table> have cellpadding="0" cellspacing="0" border="0"
Images (if any) have alt="", border="0", display:block in style
Max-width 600px enforced on container table
CTA button uses <table> + <td> structure with bgcolor= attribute, not just <a> with display:block
No flexbox, grid, position:, float:, CSS variables (--var), min-height, max-height in any inline style
border-radius on <td> only -- not on <table> or <a> (Outlook renders <td> radius)
Footer has unsubscribe link with platform-correct variable
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: .tsx component output -- request explicitly, good for Resend + dev teams
Plain text: stripped fallback always included unless user opts out
