postmark-webhooks
Receive and process Postmark webhooks. Use when setting up Postmark webhook handlers, handling email delivery events, processing bounces, opens, clicks, spam complaints, or subscription changes.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/hookdeck/webhook-skills --skill postmark-webhooks- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads postmark-webhooks automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
Postmark Webhooks
When to Use This Skill
- Setting up Postmark webhook handlers for email event tracking
- Processing email delivery events (bounce, delivered, open, click)
- Handling spam complaints and subscription changes
- Implementing email engagement analytics
- Troubleshooting webhook authentication issues
Essential Code
Authentication
Postmark does NOT use signature verification. Instead, webhooks are authenticated by including credentials in the webhook URL itself.
// Express - Basic Auth in URL
// Configure webhook URL in Postmark as:
// https://username:password@yourdomain.com/webhooks/postmark
app.post('/webhooks/postmark', express.json(), (req, res) => {
// Basic auth is handled by your web server or proxy
// Additional validation can check expected payload structure
const event = req.body;
// Validate expected fields exist
if (!event.RecordType || !event.MessageID) {
return res.status(400).send('Invalid payload structure');
}
// Process event
console.log(`Received ${event.RecordType} event for ${event.Email}`);
res.sendStatus(200);
});
// Alternative: Token in URL
// Configure webhook URL as:
// https://yourdomain.com/webhooks/postmark?token=your-secret-token
app.post('/webhooks/postmark', express.json(), (req, res) => {
const token = req.query.token;
if (token !== process.env.POSTMARK_WEBHOOK_TOKEN) {
return res.status(401).send('Unauthorized');
}
const event = req.body;
console.log(`Received ${event.RecordType} event`);
res.sendStatus(200);
});
Handling Multiple Events
// Postmark sends one event per request (not batched)
app.post('/webhooks/postmark', express.json(), (req, res) => {
const event = req.body;
switch (event.RecordType) {
case 'Bounce':
console.log(`Bounce: ${event.Email} - ${event.Type} - ${event.Description}`);
// Update contact as undeliverable
break;
case 'SpamComplaint':
console.log(`Spam complaint: ${event.Email}`);
// Remove from mailing list
break;
case 'Open':
console.log(`Email opened: ${event.Email} at ${event.ReceivedAt}`);
// Track engagement
break;
case 'Click':
console.log(`Link clicked: ${event.Email} - ${event.OriginalLink}`);
// Track click-through rate
break;
case 'Delivery':
console.log(`Delivered: ${event.Email} at ${event.DeliveredAt}`);
// Confirm delivery
break;
case 'SubscriptionChange':
console.log(`Subscription change: ${event.Email} - ${event.ChangedAt}`);
// Update subscription preferences
break;
case 'Inbound':
console.log(`Inbound email from: ${event.Email} - Subject: ${event.Subject}`);
// Process incoming email
break;
case 'SMTP API Error':
console.log(`SMTP API error: ${event.Email} - ${event.Error}`);
// Handle API error, maybe retry
break;
default:
console.log(`Unknown event type: ${event.RecordType}`);
}
res.sendStatus(200);
});
Common Event Types
| Event | RecordType | Description | Key Fields |
|---|---|---|---|
| Bounce | Bounce | Hard/soft bounce or blocked email | Email, Type, TypeCode, Description |
| Spam Complaint | SpamComplaint | Recipient marked as spam | Email, BouncedAt |
| Open | Open | Email opened (requires open tracking) | Email, ReceivedAt, Platform, UserAgent |
| Click | Click | Link clicked (requires click tracking) | Email, ClickedAt, OriginalLink |
| Delivery | Delivery | Successfully delivered | Email, DeliveredAt, Details |
| Subscription Change | SubscriptionChange | Unsubscribe/resubscribe | Email, ChangedAt, SuppressionReason |
| Inbound | Inbound | Incoming email received | Email, FromFull, Subject, TextBody, HtmlBody |
| SMTP API Error | SMTP API Error | SMTP API call failed | Email, Error, ErrorCode, MessageID |
Environment Variables
# For token-based authentication
POSTMARK_WEBHOOK_TOKEN="your-secret-token-here"
# For basic auth (if not using URL-embedded credentials)
WEBHOOK_USERNAME="your-username"
WEBHOOK_PASSWORD="your-password"
Security Best Practices
- Always use HTTPS - Never configure webhooks with HTTP URLs
- Use strong credentials - Generate long, random tokens or passwords
- Validate payload structure - Check for expected fields before processing
- Implement IP allowlisting - Postmark publishes their IP ranges
- Consider using a webhook gateway - Like Hookdeck for additional security layers
Local Development
For local webhook testing, use Hookdeck CLI:
npx hookdeck-cli listen 3000 postmark --path /webhooks/postmark
No account required. Provides local tunnel + web UI for inspecting requests.
Resources
- overview.md - What Postmark webhooks are, common event types
- setup.md - Configure webhooks in Postmark dashboard
- verification.md - Authentication methods and security best practices
- examples/ - Complete implementations for Express, Next.js, and FastAPI
Recommended: webhook-handler-patterns
For production-ready webhook handling, also install the webhook-handler-patterns skill:
- Handler sequence - Webhook processing flow
- Idempotency - Prevent duplicate processing
- Error handling - Graceful error recovery
- Retry logic - Handle transient failures
Related Skills
- sendgrid-webhooks - SendGrid webhook handling with ECDSA verification
- resend-webhooks - Resend webhook handling with Svix signatures
- stripe-webhooks - Stripe webhook handling with HMAC-SHA256
- webhook-handler-patterns - Idempotency, error handling, retry logic
- hookdeck-event-gateway - Production webhook infrastructure
FAQ
What does the postmark-webhooks skill do?
Receive and process Postmark webhooks. Use when setting up Postmark webhook handlers, handling email delivery events, processing bounces, opens, clicks, spam complaints, or subscription changes.
How do I install postmark-webhooks?
Run npx skills add https://github.com/hookdeck/webhook-skills --skill postmark-webhooks in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/postmark-webhooks/ (personal) or .claude/skills/postmark-webhooks/ (project).
Which AI agents can use postmark-webhooks?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is postmark-webhooks safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains postmark-webhooks?
It is published by hookdeck in hookdeck/webhook-skills. It has 203 recorded installs.
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