Resend Convex Component (Beta)

This component is the official way to integrate the Resend email service with your Convex project.

Features:

• Queueing: Send as many emails as you want, as fast as you want—they'll all be delivered (eventually).
• Batching: Automatically batches large groups of emails and sends them to Resend efficiently.
• Durable execution: Uses Convex workpools to ensure emails are eventually delivered, even in the face of temporary failures or network outages.
• Idempotency: Manages Resend idempotency keys to guarantee emails are delivered exactly once, preventing accidental spamming from retries.
• Rate limiting: Honors API rate limits established by Resend.

See example for a demo of how to incorporate this hook into your application.

Installation#

npm install @convex-dev/resend

Get Started#

Create a Resend account and grab an API key. Set it to RESEND_API_KEY in your deployment environment.

Next, add the component to your Convex app via convex/convex.config.ts:

import { defineApp } from "convex/server";
import resend from "@convex-dev/resend/convex.config";

const app = defineApp();
app.use(resend);

export default app;

Then you can use it, as we see in convex/sendEmails.ts:

import { components } from "./_generated/api";
import { Resend } from "@convex-dev/resend";
import { internalMutation } from "./_generated/server";

export const resend: Resend = new Resend(components.resend, {});

export const sendTestEmail = internalMutation({
  handler: async (ctx) => {
    await resend.sendEmail(
      ctx,
      "Me <test@mydomain.com>",
      "Resend <delivered@resend.dev>",
      "Hi there",
      "This is a test email"
    );
  },
});

Then, calling sendTestEmail from anywhere in your app will send this test email.

If you want to send emails to real addresses, you need to disable testMode. You can do this in ResendOptions, as detailed below.

Advanced Usage#

Setting up a Resend webhook#

While the setup we have so far will reliably send emails, you don't have any feedback on anything delivering, bouncing, or triggering spam complaints. For that, we need to set up a webhook!

On the Convex side, we need to mount an http endpoint to our project to route it to the Resend component in convex/http.ts:

import { httpRouter } from "convex/server";
import { httpAction } from "./_generated/server";
import { resend } from "./sendEmails";

const http = httpRouter();

http.route({
  path: "/resend-webhook",
  method: "POST",
  handler: httpAction(async (ctx, req) => {
    return await resend.handleResendEventWebhook(ctx, req);
  }),
});

export default http;

If our Convex project is happy-leopard-123, we now have a Resend webhook for our project running at https://happy-leopard-123.convex.site/resend-webhook.

So navigate to the Resend dashboard and create a new webhook at that URL. Make sure to enable all the email.* events; the other event types will be ignored.

Finally, copy the webhook secret out of the Resend dashboard and set it to the RESEND_WEBHOOK_SECRET environment variable in your Convex deployment.

You should now be seeing email status updates as Resend makes progress on your batches!

Speaking of...

Registering an email status event handler.#

If you have your webhook established, you can also register an event handler in your apps you get notifications when email statuses change.

Update your sendEmails.ts to look something like this:

import { components, internal } from "./_generated/api";
import { Resend } from "@convex-dev/resend";
import { internalMutation } from "./_generated/server";
import { vEmailId, vEmailEvent, Resend } from "@convex-dev/resend";

export const resend: Resend = new Resend(components.resend, {
  onEmailEvent: internal.example.handleEmailEvent,
});

export const handleEmailEvent = internalMutation({
  args: {
    id: vEmailId,
    event: vEmailEvent,
  },
  handler: async (ctx, args) => {
    console.log("Got called back!", args.id, args.event);
    // Probably do something with the event if you care about deliverability!
  },
});

/* ... existing email sending code ... */

Check out the example/ project in this repo for a full demo.

Resend component options, and going into production#

There is a ResendOptions argument to the component constructor to help customize it's behavior.

Check out the docstrings, but notable options include:

• apiKey: Provide the Resend API key instead of having it read from the environment variable.
• webhookSecret: Same thing, but for the webhook secret.
• testMode: Only allow delivery to test addresses. To keep you safe as you develop your project, testMode is default true. You need to explicitly set this to false for the component to allow you to enqueue emails to artibrary addresses.
• onEmailEvent: Your email event callback, as outlined above! Check out the docstrings for details on the events that are emitted.

Optional email sending parameters#

In addition to basic from/to/subject and html/plain text bodies, the sendEmail method allows you to provide a list of replyTo addresses, and other email headers.

Tracking, getting status, and cancelling emails#

The sendEmail method returns a branded type, EmailId. You can use this for a few things:

• To reassociate the original email during status changes in your email event handler.
• To check on the status any time using resend.status(ctx, emailId).
• To cancel the email using resend.cancelEmail(ctx, emailId).

If the email has already been sent to the Resend API, it cannot be cancelled. Cancellations do not trigger an email event.

Data retention#

This component retains "finalized" (delivered, cancelled, bounced) emails for seven days so you can check on the status of them. Then, a background job clears out those emails and their bodies to reclaim database space.