Migrate from Postmark

This guide maps Postmark concepts, API calls, webhooks, suppressions and templates to their Emailit equivalents. Read Migrate to Emailit first for the overall order and how to run both providers in parallel.

Concepts

To keep transactional and marketing reputation apart, send them from different domains or subdomains, such as mail.acme.com for receipts and news.acme.com for newsletters.

Update your API calls

Postmark’s POST /email with an X-Postmark-Server-Token becomes POST /v2/emails with a bearer token. Field names change from PascalCase to snake_case:

curl https://api.postmarkapp.com/email \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -H "X-Postmark-Server-Token: $POSTMARK_SERVER_TOKEN" \
  -d '{
    "From": "Acme <hello@acme.com>",
    "To": "ada@example.com",
    "Subject": "Your receipt",
    "TextBody": "Thanks for your order.",
    "HtmlBody": "<p>Thanks for your order.</p>",
    "MessageStream": "outbound"
  }'

curl https://api.emailit.com/v2/emails \
  -H "Authorization: Bearer $EMAILIT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "Acme <hello@acme.com>",
    "to": "ada@example.com",
    "subject": "Your receipt",
    "text": "Thanks for your order.",
    "html": "<p>Thanks for your order.</p>"
  }'

Emailit has no batch endpoint. Send one request per message, each with up to 50 recipients, and add an Idempotency-Key header so retries are safe. See Send an email.

Switch SMTP settings

Emailit doesn’t read X-PM-* headers such as X-PM-Message-Stream or X-PM-Tag. Remove them, and set tracking on the domain instead. See SMTP settings.

Map webhook events

Emailit also sends email.accepted when the API accepts an email, which Postmark has no webhook for.

The request format changes:

• Postmark posts one record per request and names it in RecordType. Emailit posts a JSON array of up to 100 events, with the name in type and the email in data.object.
• Use data.object.id, the em_ ID from the send response, instead of MessageID. Your meta values are in data.object.meta.
• Postmark webhooks are usually protected with basic authentication credentials in the URL. Emailit signs every request instead: verify X-Emailit-Signature against X-Emailit-Timestamp and your whsec_ secret. 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

1. Export the suppressions of each Postmark message stream you send from, from the stream’s suppressions page or with the suppressions dump API. Include hard bounces, spam complaints and manual suppressions.

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

   CSV

   email,type,reason
   old-address@example.com,recipient,postmark hard bounce
   angry@example.com,recipient,postmark spam complaint

   Use the type recipient for addresses that must never receive email. It blocks API, SMTP and campaign sends. For people who only opted out of your broadcasts, use the type unsubscribe, which stops campaigns but still lets transactional email through.

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.

See Manage suppressions.

Move templates

Copy each template’s HTML from Postmark, including its layout, then import it in Email Marketing›Templates or create it with the Templates API. Emailit has no layouts, so merge the layout and the content into one template. Use the same alias you used in Postmark so your code changes stay small.

Postmark templates use Mustachio. Temple covers simple values and conditions:

Temple never escapes HTML, so escape user input before you pass it. A missing value renders as an empty string unless you add a default, such as {{name|"there"}}. See Temple.

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 Postmark’s DKIM record or its pm-bounces return-path CNAME. Keep your DMARC record. After the cutover, remove the Postmark records. See DNS records.

If you process inbound mail with Postmark, move it to an Emailit inbound subdomain and update the addresses your app gives out. See Set up inbound.

Next steps

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