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 2026 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

Welcome email:

Subject: Welcome to [App Name], [First Name] 👋
Preview: Here's how to get started in 2 minutes.

Hi [First Name],

You're in. [App Name] helps you [core value in 1 sentence].

Here's the first thing to do: [single CTA — most valuable first action].

[Primary Button: Get started]

If you have any questions, just reply to this email.

— [Name], [App Name]

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.

Billing confirmation:

Subject: Your payment of [amount] was successful
Preview: Next billing date: [date].

Hi [First Name],

Your payment of [amount] for [Plan Name] went through.

Amount: [amount]
Date: [date]
Next billing date: [date]

[Button: View your invoice]

Questions about your bill? Reply here and we'll sort it out.

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:

// emails/welcome.tsx
import {
  Body, Button, Container, Head, Heading, Hr, Html,
  Link, Preview, Section, Text, Img,
} from '@react-email/components';

interface WelcomeEmailProps {
  firstName: string;
  ctaUrl: string;
}

export function WelcomeEmail({ firstName, ctaUrl }: WelcomeEmailProps) {
  return (
    <Html lang="en">
      <Head />
      <Preview>Welcome to AppName — here's how to get started.</Preview>
      <Body style={body}>
        <Container style={container}>
          <Img src="https://yourdomain.com/logo.png" width="48" height="48" alt="AppName" />
          <Heading style={h1}>Welcome, {firstName}</Heading>
          <Text style={text}>
            You're in. AppName helps you [core value in one sentence].
          </Text>
          <Text style={text}>
            Here's the first thing to do:
          </Text>
          <Section style={btnContainer}>
            <Button style={button} href={ctaUrl}>
              Get started
            </Button>
          </Section>
          <Text style={text}>
            If you have any questions, just reply to this email.
          </Text>
          <Hr style={hr} />
          <Text style={footer}>
            AppName · 123 Street · City · {' '}
            <Link href="{{{UNSUBSCRIBE_URL}}}">Unsubscribe</Link>
          </Text>
        </Container>
      </Body>
    </Html>
  );
}

const body = { backgroundColor: '#f6f9fc', fontFamily: '-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif' };
const container = { backgroundColor: '#ffffff', margin: '40px auto', padding: '40px', maxWidth: '600px', borderRadius: '8px' };
const h1 = { fontSize: '24px', fontWeight: '700', color: '#1a1a1a', marginBottom: '16px' };
const text = { fontSize: '16px', lineHeight: '1.6', color: '#444', marginBottom: '16px' };
const btnContainer = { textAlign: 'center' as const, marginBottom: '24px' };
const button = { backgroundColor: '#6366f1', borderRadius: '6px', color: '#fff', fontSize: '16px', fontWeight: '600', padding: '12px 28px', textDecoration: 'none', display: 'inline-block' };
const hr = { borderColor: '#e5e7eb', marginTop: '32px', marginBottom: '32px' };
const footer = { fontSize: '12px', color: '#9ca3af', textAlign: 'center' as const };

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)

import { Resend } from 'resend';
import { WelcomeEmail } from '../emails/welcome';
import { render } from '@react-email/render';

const resend = new Resend(process.env.RESEND_API_KEY);

await resend.emails.send({
  from: 'AppName <[email protected]>',
  to: user.email,
  subject: `Welcome to AppName, ${user.firstName}`,
  react: <WelcomeEmail firstName={user.firstName} ctaUrl={ctaUrl} />,
});

Add a Supabase Edge Function trigger (if using Supabase)

// supabase/functions/send-welcome-email/index.ts
import { serve } from 'https://deno.land/std/http/server.ts';
import { Resend } from 'npm:resend';

serve(async (req) => {
  const { record } = await req.json(); // from a database webhook
  const resend = new Resend(Deno.env.get('RESEND_API_KEY'));
  await resend.emails.send({
    from: 'AppName <[email protected]>',
    to: record.email,
    subject: `Welcome to AppName!`,
    html: '...', // rendered HTML
  });
  return new Response('OK');
});

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 [email protected])
• 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`