Migrate from Resend

This guide maps Resend concepts, API calls, webhooks and templates to their Emailit equivalents. The two APIs have a similar shape, so most code changes are small. Read Migrate to Emailit first for the overall order and how to run both providers in parallel.

Concepts

Update your API calls

Resend’s POST /emails becomes Emailit’s POST /v2/emails, with almost the same fields. In Node.js:

import { Resend } from 'resend';

const resend = new Resend(process.env.RESEND_API_KEY);

await resend.emails.send({
  from: 'Acme <hello@acme.com>',
  to: ['ada@example.com'],
  subject: 'Your receipt',
  html: '<p>Thanks for your order.</p>',
});

import { Emailit } from '@emailit/node';

const emailit = new Emailit(process.env.EMAILIT_API_KEY);

await emailit.emails.send({
  from: 'Acme <hello@acme.com>',
  to: ['ada@example.com'],
  subject: 'Your receipt',
  html: '<p>Thanks for your order.</p>',
});

Each recipient in an Emailit request becomes its own email with its own ID. When you send to several recipients, the response’s ids maps each address to its ID. Emailit also tracks opens and clicks per email with tracking: { "loads": true, "clicks": true }, once the domain has a verified tracking subdomain. See Send an email.

React Email

If you build emails with React Email, keep your components and render them yourself before you send:

import { render } from '@react-email/render';
import Receipt from './emails/receipt';

const html = await render(<Receipt order={order} />);
const text = await render(<Receipt order={order} />, { plainText: true });

await emailit.emails.send({ from, to, subject, html, text });

Switch SMTP settings

See SMTP settings.

Map webhook events

The request format changes:

• Resend posts one event per request. Emailit posts a JSON array of up to 100 events, so loop over the body.
• The email is in data.object. Use data.object.id, the em_ ID from the send response, instead of data.email_id. Your meta values are in data.object.meta.
• Signatures work differently. Resend signs webhooks through Svix, with svix-* headers. Emailit sends X-Emailit-Signature, the hex HMAC-SHA256 of <timestamp>.<raw body>, keyed with the whole secret including the whsec_ prefix. A Svix verification library won’t work, even though both secrets start with whsec_. See Request signature.

for (const event of req.body) {
  const email = event.data.object;
  if (event.type === 'email.bounced') markBounced(email.to, email.id);
  if (event.type === 'email.complained') unsubscribe(email.to);
}

Move suppressions and contacts

1. Collect every address that bounced or complained while you used Resend, from Resend’s dashboard or from the events your webhooks stored.

2. Build one CSV with the columns email,type,reason:

   CSV

   email,type,reason
   old-address@example.com,recipient,resend bounce
   angry@example.com,recipient,resend complaint

   Use the type recipient for addresses that must never receive email. It blocks API, SMTP and campaign sends.

3. In Email API›Suppressions, select Import and upload the file. Each file can have up to 10,000 rows and can be at most 8 MB. Duplicates are skipped.

If you send broadcasts, export each Resend audience as a CSV and import it in Email Marketing›Contacts with Import, choosing the matching Emailit audience. Map the unsubscribed column so people who opted out stay opted out. See Import and export contacts.

Move templates

If you render emails in code, with React Email or anything else, nothing changes: send the HTML. If you keep templates in Resend, recreate them in Email Marketing›Templates or with the Templates API, give each one an alias, and send it with template and variables.

Emailit templates use Temple: {{name}}, nested values such as {{user.name}}, defaults such as {{name|"there"}}, and {{#if plan}}…{{else}}…{{/if}}. There are no loops, so render lists in your code. Temple never escapes HTML, so escape user input before you pass it.

Change DNS

Add your domain in Email API›Domains and publish the Emailit records. They use their own names (emailit._domainkey, emailit.<domain>, and optionally go and inbound), so they don’t conflict with Resend’s records, which typically live on resend._domainkey and a send subdomain. Keep your DMARC record. After the cutover, remove the Resend records. See DNS records.

Next steps

• Go-live checklist
• Set up webhooks
• Priority migration: let Emailit engineers do the move with you