Resend

Install

Quick start

import { Chat } from "chat";
import { MemoryStateAdapter } from "@chat-adapter/state-memory";
import { createResendAdapter } from "@resend/chat-sdk-adapter";

const resend = createResendAdapter({
  fromAddress: "bot@yourdomain.com",
  fromName: "My Bot", // optional
  // apiKey: "re_...",            // or set RESEND_API_KEY
  // webhookSecret: "whsec_...",  // or set RESEND_WEBHOOK_SECRET
});

const chat = new Chat({
  userName: "email-bot",
  adapters: { resend },
  state: new MemoryStateAdapter(),
});

// New inbound email starts a new thread.
chat.onNewMention(async (thread, message) => {
  await thread.subscribe();
  await thread.post(`Got your email: ${message.text}`);
});

// Follow-up email in a subscribed thread.
chat.onSubscribedMessage(async (thread, message) => {
  await thread.post(`Reply: ${message.text}`);
});

Forward Resend webhooks to your server's webhook endpoint — the adapter verifies signatures and routes events into the Chat SDK handler pipeline. See the examples/basic folder in the adapter repo for a full working server.

Configuration

Environment variables

Email threading

Threads are resolved using the standard Message-ID, In-Reply-To, and References email headers. Reply chains are automatically grouped into Chat SDK threads — your handlers receive each follow-up as a onSubscribedMessage event on the same thread.

Sending email proactively

Use openDM to start a new email thread to any address — useful for notifications, alerts, or scheduled reports:

const threadId = await chat.adapters.resend.openDM("user@example.com");
const thread = await chat.thread("resend", threadId);
await thread.post("Hello from the bot!");

Rich card emails

Post a Chat SDK card and the adapter renders it to HTML email through @react-email/components:

await thread.post({
  card: {
    type: "card",
    title: "Order Confirmed",
    children: [
      { type: "text", content: "Your order #1234 has been shipped." },
      { type: "divider" },
      {
        type: "link-button",
        label: "Track Order",
        url: "https://example.com/track/1234",
      },
    ],
  },
  fallbackText: "Order #1234 confirmed",
});

Attachments

Inbound email attachments are exposed on message.raw.attachments as objects with filename, content_type, and url fields — your handler can fetch the URL or hand it off to downstream processing.

Limitations

Email is inherently one-shot. The following operations throw NotImplementedError:

• editMessage / deleteMessage
• addReaction / removeReaction
• startTyping

There are no native concepts for typing indicators, reactions, or message edits in email — use cards or new replies instead.

Examples

Official docs are available at resend.com/docs/chat-sdk.

Feature support