Postmark Bridge

Drop-in replacement for the Postmark email API — keep the X-Postmark-Server-Token header and your existing request structure, swap in your wemail API key.

The Postmark bridge lets you migrate from Postmark to wemail without changing your integration code. Point your base URL to https://api.wemail.io/bridge/postmark, put your wemail API key in the same X-Postmark-Server-Token header, and keep the same request bodies and response shapes — single sends, batches, outbound message search, and bounce listings all work the same way.

Authentication

Exactly like Postmark, the bridge authenticates with the X-Postmark-Server-Token header. Use your wemail API key (afn_live_… or afn_test_…) where your Postmark server token used to be. Test-environment keys route through the sandbox: messages are accepted, simulated, and never delivered.

X-Postmark-Server-Token: afn_live_YOUR_WEMAIL_KEY

Supported Endpoints

POST /bridge/postmark/email

Send a single email — mirrors Postmark's Send a single email endpoint.

POST /bridge/postmark/email/batch

Send up to 500 emails in one call — mirrors Postmark's batch endpoint with per-message results.

GET /bridge/postmark/messages/outbound

Search outbound messages — mirrors Postmark's outbound message search.

GET /bridge/postmark/bounces

List bounces — mirrors Postmark's bounce listing.

Field-Level Compatibility

POST /email — Request Fields

Response

A successful send returns 200 with { To, SubmittedAt, MessageID, ErrorCode: 0, Message: "OK" }. Validation failures return 422 with { ErrorCode, Message } using Postmark's error-code convention (300 = invalid request, 10 = auth). The batch endpoint returns an array with one result object per message — failures are per-item, exactly like Postmark.

GET /messages/outbound & GET /bounces

Both return Postmark envelopes: { TotalCount, Messages: [...] } and { TotalCount, Bounces: [...] }, paginated with count/offset. Statuses and bounce types are mapped from the wemail pipeline to Postmark vocabulary.

Webhooks

When the Postmark bridge is active, webhook deliveries are formatted exactly like Postmark webhooks: a single PascalCase object per event with RecordType (Delivery, Bounce, SpamComplaint, Open, Click), MessageID, Recipient, Tag, Metadata, and record-specific fields (Type/TypeCode/Description on bounces, Client/OS/Geo on opens and clicks). Like Postmark, payloads are not signed — protect your endpoint with HTTP auth in the URL or network rules.

Known Deviations from Postmark API

Migrating for good? Follow the Postmark migration guide — templates and suppressions auto-import, and Postmark stays warm for 30 days.

Code examples

curl -X POST https://api.wemail.io/bridge/postmark/email \
  -H "X-Postmark-Server-Token: afn_live_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "From": "sender@yourdomain.com",
    "To": "user@example.com",
    "Subject": "Hello from the Postmark bridge",
    "HtmlBody": "<p>It works — zero code changes.</p>"
  }'

// Postmark SDK — point the client at the wemail bridge
const postmark = require('postmark');

const client = new postmark.ServerClient('afn_live_YOUR_KEY', {
  requestHost: 'api.wemail.io/bridge/postmark',
});

await client.sendEmail({
  From: 'sender@yourdomain.com',
  To: 'user@example.com',
  Subject: 'Hello from the Postmark bridge',
  HtmlBody: '<p>It works — zero code changes.</p>',
});

import requests

resp = requests.post(
    "https://api.wemail.io/bridge/postmark/email",
    headers={"X-Postmark-Server-Token": "afn_live_YOUR_KEY"},
    json={
        "From": "sender@yourdomain.com",
        "To": "user@example.com",
        "Subject": "Hello from the Postmark bridge",
        "HtmlBody": "<p>It works — zero code changes.</p>",
    },
)
print(resp.status_code, resp.json())  # 200 {'MessageID': 'msg_…', 'ErrorCode': 0, ...}