Email SDK

Email SDK is a small TypeScript package for sending transactional email through swappable adapters.

Use Resend for the default path, add SMTP when you want a cheap or self-managed route, and keep a second API adapter ready for fallback. Your app code still calls the same send method.

import { createEmailClient } from "email-sdk";
import { resend } from "email-sdk/resend";

const email = createEmailClient({
  adapters: [resend({ apiKey: process.env.RESEND_API_KEY! })],
});

await email.send({
  from: "Acme <hello@acme.com>",
  to: "user@example.com",
  subject: "Welcome",
  text: "Your account is ready.",
});

Start here

What is included

• createEmailClient for one shared email client.
• email.send() for one message.
• email.sendBatch() for small batches where each result is reported separately.
• Fifteen adapters, including Resend, SMTP, Postmark, SendGrid, Mailgun, and MailerSend.
• Retry, fallback, and hook options.
• A small CLI for adapter setup checks and test sends.
• A repo-local agent skill for future coding agents.

What stays small

Email SDK does not try to be a template engine, campaign tool, analytics platform, or full email operations suite. The first version is the layer most apps keep rebuilding: adapter setup, a consistent send call, typed errors, and a clean fallback path.