Relay

Developer-friendly email delivery platform. SendGridの代替、Resendのオープンな競合。

What is Relay?

Relay は、開発者とビジネスのためのメール配信プラットフォームです。SendGrid が無料プランを廃止する中、シンプルで手頃な価格のメール配信を提供します。

Why Relay?

• SendGrid からの移行が簡単 - SMTP / API どちらでも接続可能
• マルチテナント対応 - 1つのインスタンスで複数組織を管理
• コンタクト管理 - CSV / Google Workspace からインポート
• 一斉配信 - オーディエンス（リスト）を作って一括送信
• テンプレートエンジン - {{variables}} でパーソナライズ
• 配信停止管理 - ワンクリック配信停止リンク自動挿入
• 開封・クリック追跡 - トラッキングピクセル & リダイレクト
• セルフホスト可能 - Docker Compose で即座に起動

Tech Stack

Layer	Technology
API	Hono + Node.js
Database	SQLite (dev) / PostgreSQL (prod)
ORM	Drizzle
Dashboard	React 19 + Vite + Tailwind CSS v4
Auth	Google OAuth 2.0
Email	SMTP (Nodemailer) / SendGrid / Amazon SES
Deploy	Docker / Cloud Run

Quick Start

# Install
git clone https://github.com/tsubasagit/relay.git
cd relay
npm install

# Start dev servers (API: 3456, Dashboard: 5173)
npm run dev

Environment Variables

# packages/api/.env
DATABASE_PATH=./data/relay.db
API_PORT=3456
API_BASE_URL=http://localhost:3456
GOOGLE_CLIENT_ID=your-client-id.apps.googleusercontent.com
GOOGLE_CLIENT_SECRET=your-secret
GOOGLE_CALLBACK_URL=http://localhost:3456/auth/google/callback
SESSION_SECRET=change-this-in-production
ENCRYPTION_KEY=64-char-hex-string

Features

Email Sending

• Single email via API or dashboard
• Bulk broadcast to audience lists
• Template-based with variable substitution
• Multiple provider support (SMTP, SendGrid, SES)

Contact Management

• Manual add / edit / delete
• CSV bulk import
• Google Workspace directory import
• Unsubscribe status tracking

Audiences

• Create named lists (e.g., "Newsletter subscribers")
• Add/remove contacts with search
• Use as broadcast targets

Broadcasts

• Select audience + template + sending address
• Background async processing (non-blocking)
• Real-time progress tracking (polling)
• Automatic unsubscribe link injection
• Rate-limited sending (50ms interval)
• Skip unsubscribed contacts

Analytics

• Delivery logs with status filtering
• Open rate / click rate tracking
• Per-broadcast detailed stats

Organization Management

• Multi-tenant with role-based access (admin/member)
• Domain verification via DNS TXT record
• API key management (rl_live_ prefix)
• Provider config encryption (AES-256-GCM)

API

# Send email
curl -X POST http://localhost:3456/api/emails/send \
  -H "Authorization: Bearer rl_live_xxxxx" \
  -H "Content-Type: application/json" \
  -d '{"to":"user@example.com","subject":"Hello","html":"<p>Hi!</p>"}'

SDK

import { RelayClient } from "@relay-email/sdk";

const relay = new RelayClient({
  baseUrl: "https://your-relay-instance.com",
  apiKey: "rl_live_xxxxx",
});

await relay.sendEmail({
  to: "user@example.com",
  templateId: "tmpl_xxxx",
  variables: { name: "John" },
});

License

MIT