Adapter model

An adapter is an Email SDK module that knows how to send through one service or transport.

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

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

Routing names

Each adapter registers a routing name. Email SDK uses that name for defaults, fallbacks, and per-send overrides.

Send with one adapter

await email.send(message, {
  adapter: "postmark",
});

Adapters are route names

Adapter names are the route identifiers used by defaultAdapter, per-send adapter, client-level fallback, per-send fallbackAdapters, and withAdapter.

Use Fallbacks and retries to understand route order. Use Field support before choosing backup routes.

Bind one adapter

const transactional = email.withAdapter("postmark");

await transactional.send(message);

Use adapter escape hatches

Every adapter can expose raw. Keep provider-specific code close to the adapter and keep normal application code on the shared send path.

const adapter = email.adapter("resend");

console.log(adapter.raw);

The older provider, defaultProvider, email.provider(), and email.withProvider() names still work as aliases.