building-email-newsletters
SKILL.md
Email Newsletter Template Builder
When to use this skill
- User asks to create a newsletter
- User needs email subject lines
- User wants email campaign templates
- User mentions email marketing copy
- User needs A/B testing variants
Workflow
- Identify email type and goal
- Generate subject line variants
- Create preheader text
- Build email structure
- Write content blocks
- Add CTAs and footer
Instructions
Step 1: Identify Email Type
| Email Type | Goal | Structure |
|---|---|---|
| Newsletter | Engagement, value | Hero + 3-5 content blocks |
| Promotional | Sales, conversions | Hero + offer + CTA |
| Welcome | Onboarding | Personal intro + next steps |
| Announcement | Awareness | News + details + CTA |
| Re-engagement | Win-back | Hook + incentive + CTA |
| Transactional | Information | Order details + support |
Step 2: Subject Line Generation
Subject line formulas:
| Formula | Example |
|---|---|
| Number + Benefit | "5 ways to speed up your website today" |
| How to + Outcome | "How to double your open rates" |
| Question | "Is your portfolio costing you interviews?" |
| Curiosity gap | "The one thing top developers never skip" |
| Urgency | "Last chance: 40% off ends tonight" |
| Personal | "John, your weekly digest is ready" |
| FOMO | "Everyone's talking about this new feature" |
| Direct benefit | "Get 3 hours back every week" |
Subject line best practices:
- 30-50 characters (mobile preview)
- Front-load key information
- Avoid spam triggers (FREE!!!, š°š°š°)
- Test with/without emoji
- Match preheader text
A/B test variants:
## Subject Line Variants
**Version A (Benefit-focused):**
Subject: 5 tools that cut my development time in half
Preheader: Plus the one tool I stopped using
**Version B (Curiosity):**
Subject: I stopped using this popular tool
Preheader: And my productivity doubled
**Version C (Question):**
Subject: Are you still using [Tool]?
Preheader: There's a faster alternative
Step 3: Preheader Text
Preheader guidelines:
- 40-100 characters
- Complement (don't repeat) subject
- Add context or secondary hook
- Include CTA preview if relevant
| Subject | Poor Preheader | Good Preheader |
|---|---|---|
| "5 ways to speed up your site" | "Read our latest blog post" | "Plus the #1 mistake slowing you down" |
| "Your order has shipped" | "Order confirmation" | "Arrives Thursday. Track it here ā" |
Step 4: Email Structure Templates
Newsletter template:
<!-- Preheader (hidden) -->
<span style="display:none;">[Preheader text here]</span>
<!-- Header -->
[Logo] [Navigation: Blog | Products | Contact]
<!-- Hero Section -->
[Featured image or heading] [Brief intro: 2-3 sentences] [Primary CTA button]
<!-- Content Block 1 -->
[H2: Section title] [Thumbnail image] [Summary: 2-3 sentences] [Read more link]
<!-- Content Block 2 -->
[H2: Section title] [Thumbnail image] [Summary: 2-3 sentences] [Read more link]
<!-- Content Block 3 -->
[H2: Section title] [Thumbnail image] [Summary: 2-3 sentences] [Read more link]
<!-- Secondary CTA -->
[H2: Call to action heading] [Brief value prop] [CTA button]
<!-- Footer -->
[Social icons] [Unsubscribe | Preferences | View in browser] [Company address]
[Copyright]
Promotional template:
<!-- Preheader -->
<span style="display:none;">[Urgency or key offer]</span>
<!-- Header -->
[Logo]
<!-- Hero -->
[Bold headline with offer] [Hero image of product/service] [Key benefit: 1
sentence] [Primary CTA: "Shop Now" / "Get Started"]
<!-- Social Proof -->
[Testimonial or rating] [Customer logo bar]
<!-- Benefits -->
[Benefit 1 with icon] [Benefit 2 with icon] [Benefit 3 with icon]
<!-- Urgency -->
[Countdown or deadline] [Secondary CTA]
<!-- Footer -->
[Unsubscribe | View in browser] [Address]
Welcome email template:
<!-- Preheader -->
<span style="display:none;">Here's what to do first...</span>
<!-- Header -->
[Logo]
<!-- Hero -->
[Personalized greeting: "Welcome, {first_name}!"] [What they signed up for /
what to expect] [Founder photo or brand image]
<!-- Quick Wins -->
[H2: Get started in 3 steps] [Step 1] [Icon + title + 1-sentence description]
[Step 2] [Icon + title + 1-sentence description] [Step 3] [Icon + title +
1-sentence description] [Primary CTA: "Complete your profile" / "Start
tutorial"]
<!-- Value Reminder -->
[H2: What you'll get] [Bullet list of benefits]
<!-- Personal Touch -->
[Sign-off from founder/team] [Photo + signature] [P.S. line with secondary offer
or tip]
<!-- Footer -->
[Support link] [Social icons] [Unsubscribe | Preferences]
Step 5: Content Block Writing
Block structure:
## [Compelling headline]
[1-2 sentences summarizing the value or key point]
[Optional: key stat or quote]
[CTA: "Read more ā" or "Watch now ā"]
Block examples:
## Why Your Images Are Slowing Down Your Site
Large, unoptimized images are the #1 cause of slow page loads.
Here's how to fix it in under 10 minutes.
ā Read the full guide
---
## New Feature: Dark Mode Support
You asked, we delivered. Enable dark mode in your dashboard
settings for easier late-night work sessions.
ā Try it now
---
## Case Study: How Acme Corp Increased Conversions 47%
See exactly how they optimized their checkout flow and
the surprising change that made the biggest difference.
ā Read the case study
Step 6: CTA Best Practices
Button copy:
| Weak | Strong |
|---|---|
| Click here | Get your free guide |
| Submit | Start my trial |
| Learn more | See how it works |
| Buy now | Add to cart - $29 |
| Download | Download the checklist |
CTA guidelines:
- Action verb + benefit
- 2-5 words
- First person ("Get my..." vs "Get your...")
- Contrast color from email background
- Minimum 44x44px tap target
Step 7: Footer Requirements
Required elements:
<!-- Social Links -->
<a href="#">Twitter</a> | <a href="#">LinkedIn</a> | <a href="#">Instagram</a>
<!-- Legal -->
<p>You're receiving this because you signed up at [website].</p>
<a href="{unsubscribe_link}">Unsubscribe</a> |
<a href="{preferences_link}">Email preferences</a> |
<a href="{browser_link}">View in browser</a>
<!-- Address (CAN-SPAM required) -->
<p>
[Company Name]<br />
[Street Address]<br />
[City, State ZIP]
</p>
<!-- Copyright -->
<p>Ā© 2026 [Company Name]. All rights reserved.</p>
Step 8: Mobile Optimization
Mobile-first guidelines:
| Element | Mobile Spec |
|---|---|
| Width | 100%, max 600px |
| Font size | Body 16px+, headings 22px+ |
| Line height | 1.5-1.6 |
| Button size | Full width, 48px height min |
| Images | 100% width, max-width set |
| Padding | 20px sides minimum |
| Single column | Stack all content vertically |
Responsive image:
<img
src="image.jpg"
alt="Description"
width="600"
style="max-width: 100%; height: auto; display: block;"
/>
Step 9: Testing Checklist
Before sending:
- Subject line under 50 characters
- Preheader complements subject
- All links working
- Images have alt text
- Unsubscribe link present
- Physical address included
- Renders on mobile (test with Litmus/Email on Acid)
- Plain text version included
- Personalization tokens work ({first_name})
- Sent from recognizable sender name
Output Format
## Email Campaign: [Name]
**Type:** [Newsletter/Promotional/Welcome/etc.]
**Goal:** [Engagement/Sales/Onboarding/etc.]
---
### Subject Line Variants
**A:** [Subject line]
**B:** [Subject line variant]
**Preheader:** [Preheader text]
---
### Email Content
[Full email content with sections marked]
---
### Notes
- Send time: [Recommended day/time]
- Segment: [Target audience]
- A/B test: [What to test]
Validation
Before completing:
- Subject line A/B variants provided
- Preheader text included
- Clear value in first paragraph
- CTAs are action-oriented
- Mobile-friendly structure
- Footer has required elements
- Consistent with brand voice
Error Handling
- No clear goal: Ask for campaign objective (traffic, sales, engagement).
- Too much content: Limit to 3-5 content blocks; link to full articles.
- Missing personalization: Add {first_name} or segment-specific content.
- Spam trigger words: Avoid "FREE", "Act now", excessive caps/punctuation.
- No mobile consideration: Use single column, large fonts, stacked CTAs.
Resources
- Really Good Emails - Inspiration
- Litmus - Email testing
- Mail-Tester - Spam score check
- Email on Acid - Cross-client testing
Weekly Installs
3
Repository
wesleysmits/agent-skillsGitHub Stars
2
First Seen
Jan 24, 2026
Security Audits
Installed on
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