Migrating from Resend to Sendpository

Or let your coding agent do the whole migration

Paste it in. It finds every Resend call, rewrites it, updates your webhook handler and switches over behind a flag you can flip back.

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Switch this project's email from Resend to Sendpository. First run `npx sendpository@latest init` - it opens my browser for me to approve, saves the API key and installs the Sendpository skill - then follow the skill's migration guide (references/migrate.md). If you can't run commands, read https://www.sendpository.com/agents/sendpository/references/migrate.md instead.

1. API differences

2. Authentication differences

3. Domain setup

4. Webhooks

Event names

5. Error handling

6. Code migration

import { Resend } from "resend";

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

const { data, error } = await resend.emails.send({
  from: "Acme <billing@yourdomain.com>",
  to: ["customer@example.com"],
  subject: "Your receipt",
  html: "<p>Thanks for your order.</p>",
  tags: [{ name: "type", value: "receipt" }],
});

import { Sendpository, SendpositoryError } from "sendpository";

const sendpository = new Sendpository(process.env.SENDPOSITORY_API_KEY);

try {
  const { id } = await sendpository.emails.send(
    {
      from: "Acme <billing@mail.yourdomain.com>",
      to: ["customer@example.com"],
      subject: "Your receipt",
      html: "<p>Thanks for your order.</p>",
      text: "Thanks for your order.",
      tags: { type: "receipt" },
    },
    // A retried job returns the first message's id instead of sending twice.
    { idempotencyKey: "receipt-10428" },
  );
  console.log(id);
} catch (err) {
  if (err instanceof SendpositoryError) console.error(err.type, err.message);
  throw err;
}

Watch out for

• Rewrite tags from [{ name, value }] to { name: value } - an array is rejected.
• Replace the Svix verification with verifyWebhook from the sendpository package; the Svix headers will be absent.
• Resend's SDK returns { data, error }. Sendpository's SDK throws a SendpositoryError instead - wrap sends in try/catch.
• Rename email.delivery_delayed to email.delayed in your event switch.

7. Pricing

8. Things to test before switching

• Re-send a message whose tags you had set as an array. Resend takes `[{name, value}]`; ours takes a plain object, and a tag silently dropped is a filter that stops matching in the logs.
• Replace the Svix signature check. Resend signs through Svix with its own header set; ours is a single `Sendpository-Signature` with the timestamp inside the signed content, so the old verification code will reject every delivery until it is swapped.
• Confirm anything built on React Email still renders. The templates are yours and keep working - they just produce HTML you now pass as `html` rather than handing the component to the SDK.

• Send to a real Gmail and a real Outlook address and open Show original: SPF, DKIM and DMARC should all say PASS, with DKIM signed as your own domain.
• Send a message with an attachment and one with an inline image, and check both render.
• Trigger a bounce (an address at a domain you control with no mailbox) and confirm your webhook handler receives email.bounced and marks the address.
• Send the same request twice with one Idempotency-Key and confirm only one email arrives.
• Point a staging environment at the new API key first, and watch the Logs page for 4xx responses before switching production.
• Keep the old provider's DNS records until the new domain has verified and a day of production mail has been delivered - removing them first breaks mail still in flight.

Questions

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