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Antigravity Agent 93ec7e9056 [G1-Sync] Manual knowledge update

2026-05-09 21:08:02 +09:00

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title

Transactional Email

사용자 행동 트리거 (가입, 영수증). 마케팅과 분리, 별 IP / 별 도메인 권장. 도구: Resend / Postmark / SendGrid. 템플릿: React Email / MJML. SPF/DKIM/DMARC 필수.

📖 핵심 개념

Transactional vs Marketing: 다른 IP / 도메인 / sender reputation.
SPF / DKIM / DMARC: spoofing 방어 + spam 회피.
Bounce / Complaint: 처리 안 하면 reputation 망가짐.
Idempotency: 같은 이벤트로 두 번 보내면 안 됨.

💻 코드 패턴

Resend (modern)

import { Resend } from 'resend';

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

await resend.emails.send({
  from: 'Acme <noreply@mail.acme.com>',
  to: user.email,
  subject: 'Welcome to Acme',
  html: render(<WelcomeEmail name={user.name} />),
  headers: { 'X-Idempotency-Key': eventId },
});

React Email 템플릿

import { Body, Container, Head, Heading, Html, Link, Preview, Text } from '@react-email/components';

export function WelcomeEmail({ name }: { name: string }) {
  return (
    <Html>
      <Head />
      <Preview>Welcome to Acme, {name}</Preview>
      <Body style={{ backgroundColor: '#f6f9fc', fontFamily: 'system-ui' }}>
        <Container style={{ padding: '40px 20px' }}>
          <Heading>Welcome, {name}!</Heading>
          <Text>Click <Link href="https://acme.com/start">here</Link> to start.</Text>
        </Container>
      </Body>
    </Html>
  );
}

import { render } from '@react-email/render';
const html = await render(<WelcomeEmail name="A" />);
const text = await render(<WelcomeEmail name="A" />, { plainText: true });

큐 + retry

// 직접 보내지 말고 큐
queue.add('email', { to, template, data, idempotencyKey });

queue.process('email', async (job) => {
  const sent = await db.emails.find(job.data.idempotencyKey);
  if (sent) return; // 이미 보냄

  const r = await resend.emails.send({...});
  await db.emails.insert({ idempotencyKey: job.data.idempotencyKey, providerId: r.id });
});

Bounce / complaint webhook

app.post('/webhooks/email', async (req, res) => {
  // SES SNS / SendGrid event webhook / Resend webhook
  const ev = req.body;
  if (ev.type === 'email.bounced') {
    await db.users.update(ev.email, { emailValid: false });
  }
  if (ev.type === 'email.complained') {
    await db.users.update(ev.email, { emailMarketingOptOut: true, emailValid: false });
  }
  res.json({ ok: true });
});

SPF / DKIM / DMARC DNS

# SPF
mail.acme.com.  TXT  "v=spf1 include:_spf.resend.com -all"

# DKIM (Resend / SendGrid 가 제공하는 CNAME)
resend._domainkey.mail.acme.com.  CNAME  resend._domainkey.acme.com.resend.email.

# DMARC
_dmarc.mail.acme.com.  TXT  "v=DMARC1; p=quarantine; rua=mailto:dmarc@acme.com"

Marketing 분리

Transactional: noreply@mail.acme.com
Marketing:     hello@news.acme.com

다른 sub-domain → bounce 가 transactional 평판에 안 영향.

Plain text + HTML 둘 다

await resend.emails.send({
  from, to, subject,
  html: render(<Email />),
  text: render(<Email />, { plainText: true }), // spam 점수 낮춤
});

Preview tools

React Email dev server: 라이브 preview.
Mailtrap / Litmus: 다양한 client 렌더 테스트.

다국어

const html = await render(<WelcomeEmail name={name} t={i18n.t} />, { locale: user.locale });

🤔 의사결정 기준

종류	추천
작은 SaaS / modern stack	Resend
큰 규모 / 분석 강함	SendGrid / Mailgun
Bounce 까다로움	Postmark (transactional 전문)
자체 메일 서버	SES (싸지만 복잡)
Email 아닌 SMS	Twilio / MessageBird
마케팅 자동화	Customer.io / Loops

❌ 안티패턴

DKIM 없음: spam 폴더 직행.
Marketing 같은 도메인: bounce 가 transactional 평판 망가짐.
Bounce 처리 안 함: 평판 추락 → 모두 spam.
Throttle 없이 대량: rate limit hit.
Idempotency 없음: 같은 이벤트 여러 번 메일.
Plain text 누락: 일부 client / spam 점수 ↑.
Inline image base64: 큰 메일 + 일부 client 차단. 호스팅된 URL.
Subject 가 spam-trigger: "FREE!!!" 같은.

🤖 LLM 활용 힌트

Resend + React Email + 큐 + bounce webhook 4종.
SPF/DKIM/DMARC 자동 사이트 (mxtoolbox) 검증.
transactional 따로 sub-domain.

4.9 KiB Raw Blame History