design-email — Email Templates That Actually Get Read

Degree of freedom: MIXED. Copy and layout judgment [HIGH freedom]; stack detect, markup, send, and preview [LOW freedom — run exactly].

Email is the one channel users check before they check your app. A well-crafted transactional email — clear, warm, fast-loading, and readable on any device — builds trust. A corporate, jargon-heavy, broken email erodes it. This skill handles design and copy. Inbox placement / SPF DKIM DMARC is enhance-email-deliverability.

How to reason

1. Detect — React Email vs MJML vs none
2. Audit — copy voice, subject, one action; client-safe layout
3. Write — specific subject, human "you", plain-text twin
4. Preview — 375px + dark mode; hand DNS off

Worked example

Detect: @react-email/components already in package.json; emails/ has a receipt only. Audit: password-reset subject is "Account notification"; two CTAs; no preview text. Write: subject "Reset your App password"; one "Reset my password" button; expiry in the first sentence. Preview: npx email dev at 375px; tap target ≥44px; DNS/spam → enhance-email-deliverability.

Self-critique before reporting

• One action — exactly one primary CTA; subject is specific and honest
• Client-safe — 600px single column, inline styles, alt text, dark fallback
• Human copy — "you"/"we"; no jargon or ALL-CAPS subject
• Right owner — SPF / DKIM / DMARC / bounces / List-Unsubscribe → enhance-email-deliverability

Phase 0: Detect the stack [LOW freedom — run exactly]

package.json        → @react-email/*, mjml, nodemailer, @sendgrid/mail,
                      resend, @aws-sdk/client-ses, postmark
emails/             → existing React Email templates
src/emails/         → email template directory
.env.*              → RESEND_API_KEY, SENDGRID_API_KEY, etc. (reference by name only)

Phase 1: Audit existing templates [HIGH freedom]

If templates already exist, walk through each one and check:

Copy quality:

• Does it sound like a person sent it, or a system?
• Is the subject line specific? ("Your order is on its way" not "Order notification")
• Is the first sentence the most important one (preview text matters)?
• Does it tell the reader exactly what to do and what happens next?
• Is it free of business jargon, technical terms, and passive voice?

Design:

• Single-column layout? (Most reliable across clients)
• Max-width 600px? (Standard email width)
• All styles inline? (Gmail strips <style> tags)
• Images have alt text? (Many clients block images by default)
• Dark mode support? (@media (prefers-color-scheme: dark) + inline fallbacks)
• Mobile: tap targets ≥ 44px, font size ≥ 14px

Sender identity (template-side):

• "From" address uses the app domain, not a personal Gmail?
• SPF / DKIM / DMARC / bounces → enhance-email-deliverability

Phase 2: Research best practices [HIGH freedom]

firecrawl:firecrawl_search
{
  "query": "transactional email design best practices [current year] React Email",
  "limit": 3,
  "sources": [{ "type": "web" }]
}

Fetch React Email docs if using it:

context7:resolve-library-id
{
  "libraryName": "react-email"
}

Phase 3: Copy principles [HIGH freedom]

Apply these to every email before looking at design:

Common email types — copy templates

Password reset:

Subject: Reset your [App Name] password
Preview: Your link expires in 1 hour.

Hi [First Name],

Someone requested a password reset for your [App Name] account.
If that was you, click the button below. If not, you can ignore this email.

[Primary Button: Reset my password]

This link expires in 1 hour. After that, you'll need to request a new one.

Welcome (subject with first name, preview "get started in 2 minutes", one Get started button, "just reply" close) and Billing confirmation (subject "Your payment of [amount] was successful", amount/date/next billing date lines, View your invoice button): references/copy-templates.md.

Phase 4: Build the template (React Email) [LOW freedom — run exactly]

Install if not present:

npm install react-email @react-email/components

Base template structure: Html lang → Head → Preview → Body → Container (600px max, white on off-white) with Img logo (alt text), Heading, Text, one Button in a centered Section, Hr, and a footer Text with address + {{{UNSUBSCRIBE_URL}}} link. Styles are inline objects; swap the indigo button and off-white ground for the brand. Full emails/welcome.tsx: references/react-email-and-send.md §Base template.

Dark mode support

// In <Head>:
<style>{`
  @media (prefers-color-scheme: dark) {
    .email-body { background-color: #1a1a1a !important; }
    .email-container { background-color: #2d2d2d !important; }
    .email-text { color: #e5e7eb !important; }
    .email-heading { color: #f9fafb !important; }
  }
`}</style>
// Add className to Body, Container, Text, Heading components to match

Phase 5: Send via provider [LOW freedom — run exactly]

Resend (recommended for new projects)

new Resend(process.env.RESEND_API_KEY) → resend.emails.send({ from: 'AppName <hello@yourdomain.com>', to, subject, react: <WelcomeEmail … /> }). Code: references/react-email-and-send.md §Send with Resend.

Add a Supabase Edge Function trigger (if using Supabase)

supabase/functions/send-welcome-email/index.ts: Deno serve, read record from the database webhook body, npm:resend with Deno.env.get('RESEND_API_KEY'), send rendered HTML, return OK. Code: references/react-email-and-send.md §Supabase Edge Function trigger.

Deploy:

supabase functions deploy send-welcome-email --no-verify-jwt

Phase 6: Content flags that hurt placement [LOW freedom — do not skip]

DNS auth, bounces, and List-Unsubscribe headers are enhance-email-deliverability. This phase only owns copy/markup that templates can fix:

• From address uses your domain (not noreply@gmail.com)
• Reply-To set if replies should go somewhere useful
• No ALL-CAPS words in subject line
• No spam trigger words: "FREE", "URGENT", "ACT NOW", "GUARANTEED"
• Plain text version matches the HTML version
• Hand remaining inbox-placement work to enhance-email-deliverability

Phase 7: Preview and test [LOW freedom — run exactly]

Start the React Email preview server:

npx email dev --dir emails --port 3001

Then check with Playwright:

PW="npx --yes @playwright/cli@latest"
$PW -s=email-preview open --headed http://localhost:3001
$PW -s=email-preview snapshot                                  # verify each template renders
$PW -s=email-preview resize 375 812                            # mobile — font size, tap targets
$PW -s=email-preview screenshot --filename ".playwright-mcp/email-mobile.png"

For cross-client testing, use Litmus or Email on Acid. Key clients to test:

• Gmail (web + Android + iOS)
• Apple Mail (macOS + iOS)
• Outlook (Windows — most restrictive CSS support)
• Samsung Mail

Email templates checklist

Design:
- [ ] Max-width 600px
- [ ] Single column
- [ ] All styles inline (no <style> blocks except dark mode)
- [ ] Images have alt text
- [ ] Buttons ≥ 44px tall, large enough to tap
- [ ] Font size ≥ 14px on body text
- [ ] Dark mode tested

Copy:
- [ ] Subject line is specific and honest
- [ ] Preview text set and meaningful
- [ ] First sentence is the most important thing
- [ ] Exactly one primary action
- [ ] Copy sounds like a person wrote it
- [ ] No jargon or passive voice
- [ ] Plain text version exists

Deliverability (handoff — do not own here):
- [ ] From address on app domain
- [ ] Plain-text alternative present
- [ ] SPF / DKIM / DMARC / bounces / unsubscribe headers → `enhance-email-deliverability`