Migrating from Postmark to Sendpository

Or let your coding agent do the whole migration

Paste it in. It finds every Postmark 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 Postmark 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

await fetch("https://api.postmarkapp.com/email", {
  method: "POST",
  headers: {
    "X-Postmark-Server-Token": process.env.POSTMARK_SERVER_TOKEN,
    "Content-Type": "application/json",
    Accept: "application/json",
  },
  body: JSON.stringify({
    From: "Acme <billing@yourdomain.com>",
    To: "customer@example.com",
    Subject: "Your receipt",
    HtmlBody: "<p>Thanks for your order.</p>",
    TextBody: "Thanks for your order.",
    Tag: "receipt",
    MessageStream: "outbound",
  }),
});

const res = await fetch("https://api.sendpository.com/v1/emails", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.SENDPOSITORY_API_KEY}`,
    "Content-Type": "application/json",
    "Idempotency-Key": "receipt-10428",
  },
  body: JSON.stringify({
    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" },
  }),
});

const body = await res.json();
if (!res.ok) throw new Error(`${body.error.type}: ${body.error.message}`);
console.log(body.id);

Watch out for

• To becomes an array - split any comma-separated recipient string.
• A single Tag becomes a key in tags, e.g. { "type": "receipt" }.
• If you relied on ErrorCode 406 to skip inactive recipients, check for error.type === "suppressed_recipient" instead.
• Webhook handlers should verify the signature; the basic-auth credentials in the URL are no longer needed.

7. Pricing

8. Things to test before switching

• Decide which Message Stream each send belonged to. Postmark separates transactional and broadcast streams with their own reputations; we have one sending reputation per domain, so anything you were sending on a broadcast stream needs its unsubscribe handling checked.
• Check anything that relied on 45-day full-content retention. Our logs keep the metadata and events for the full window but the body for a shorter one, so export anything you depend on before you cut over.
• Swap the `X-PM-Message-Id` header if you correlate on it. Ours returns an `id` in the response body instead.

• 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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