Category
Resend 実装ガイド（送信APIと冪等キー／Next.js App Router 実装／ドメイン認証 SPF・DKIM・DMARC と到達率／Webhook 署名検証とバウンス・苦情処理／一括送信・予約送信・購読管理／テンプレートと React Email／SES・SendGrid・Postmark との技術選定）
メール送信は「APIが200を返した」で終わりません。本番で満たすべき条件は3つ——届く（認証とレピュテーション）・追える（Webhookと構造化ログ）・二重に送らない（冪等性）。本クラスタはこの3条件を Resend でどう満たすかに集中します。ピラーで2026年時点の正しい全体像（audiences は非推奨で segments が正、Templates/Topics/Segments/Suppressions/受信の追加、User-Agent ヘッダ必須、Free/Pro/Scale/Enterprise の4プラン）を示し、各論で Next.js App Router からの型安全な送信経路（Zod・レート制限・エスケープ・構造化ログ）、send サブドメインに置く SPF/DKIM/DMARC（ルートドメインへの誤配置は送信を全滅させる）、失敗を retryable / sender_rejected / fatal に分けて扱うリトライと冪等キー、署名検証と at-least-once 前提の冪等な Webhook 受信、batch の strict/permissive と scheduledAt による予約送信、Segments・Topics とワンクリック購読解除（RFC 8058）・特定電子メール法、Templates と React Email の使い分け、そして SES/SendGrid/Postmark との技術選定までを体系化します。このポートフォリオ自身の問い合わせ・資料請求・7通のメール講座・決済後の納品メールを Resend で本番運用し、認証レコードをルートドメインに誤配置して送信が全滅した実障害を DNS 修正・送信者フォールバック・冪等キーで根治した経験、および冪等性で本番二重課金0件を達成した決済信頼性レイヤーの知見を根拠に、公式ドキュメントに忠実な実コードで解説します。決済側の冪等性は「決済・課金」クラスタ、Next.js そのものの実装は「フロントエンド」クラスタを参照してください。
8 articles in total
Foundational guide
Foundational guide (start here)
Resend in Production: Domain Authentication, Idempotent Sends, Webhooks, and Deliverability
A production guide faithful to the Resend docs (August 2026): DNS traps that break domain verification, type-safe sending, idempotency and retries, webhooks, and real plan costs.
Related practical articles
- Resendメール配信TypeScriptNext.js到達率
Resend batch, scheduled sends, and Broadcasts: Segments/Topics, one-click unsubscribe, and Japan's anti-spam law
Everything in Resend beyond sending one email at a time: batch strict vs permissive, scheduledAt and cancel, Segments/Topics, Broadcasts, and RFC 8058 one-click unsubscribe.
26 min read - Resendメール配信SPF/DKIM/DMARC到達率インフラ
Resend Domain Authentication and Deliverability: Putting SPF, DKIM and DMARC on the Right Hostnames
Most Resend domain verification failures are a DNS hostname problem: SPF on send, DKIM on resend._domainkey, DMARC on _dmarc. Plus dig checks and safe DMARC rollout.
30 min read - Resendメール配信冪等性信頼性TypeScript
Resend Idempotency Keys, Retries, and Error Classification: Never Lose a Lead to One Failed Send
Resend's Node SDK never throws — it returns { data, error }. Sort failures into retryable / sender_rejected / fatal, then wire up Idempotency-Key (1–256 chars, 24 hours), exponential backoff, timeouts, and deterministic tests, in production TypeScript.
22 min read - ResendNext.jsTypeScriptメール配信React Email
Resend × Next.js App Router: building production-quality email sending with Route Handlers and Server Actions
A production-grade guide to calling Resend from the Next.js App Router: why you must never call it from the browser, the seven things the official minimal sample is missing, and Zod validation, rate limiting, spam absorption, HTML escaping, lazy init, idempotencyKey, and structured logging — all from code running in production.
22 min read - ResendReact Emailメール配信TypeScriptNext.js
Designing Resend Email Templates: React Email vs. the Templates API in Production
Should your email body live in code (React Email) or in Resend Templates? Triple-brace variables, the draft/publish split, the current render signature, and Tailwind's limits — faithful to the official docs and to the resend@6.4.1 type definitions.
21 min read - Resendメール配信技術選定コスト最適化AWS
Resend vs. Amazon SES vs. SendGrid vs. Postmark: How to Actually Choose an Email Provider (August 2026)
Pick an email provider by which job you do not want to own, not by price. Official 2026 pricing, limits and TCO for Resend, Amazon SES, SendGrid and Postmark.
23 min read - ResendWebhook冪等性信頼性Next.js
Resend Webhooks in Production: Signature Verification, Idempotent Receipt, and Bounce/Complaint Handling
A production webhook guide faithful to the Resend docs (as of August 2026) and the resend@6.4.1 implementation: all 19 event types, correct svix signature verification, idempotent receipt keyed on svix-id, the retry policy, hard bounce and complaint operations, and storage design — in TypeScript that actually runs.
25 min read