How do I process delivery events from an email provider?

To process delivery events from an email provider, treat them as webhooks: your provider sends your app HTTP notifications when an email is accepted, delivered, bounced, opened, clicked, etc.

1) Set up a webhook endpoint

Create an HTTPS endpoint in your app, for example:

• POST /webhooks/email-events

It should:

• accept JSON payloads
• return a fast 200 OK
• be idempotent
• verify the sender/authenticity of the event

2) Verify the event

Before trusting the payload, validate it using one or more of:

• webhook signature header
• HMAC secret
• provider-issued token
• IP allowlist
• timestamp/replay protection

This prevents forged events.

3) Parse the event type

Providers usually send an event like:

• delivered
• bounce
• deferred
• opened
• clicked
• complained
• unsubscribed

Typical fields include:

• message_id
• recipient
• event_type
• timestamp
• reason or error
• metadata / custom args

4) Store the event

Save raw events in a database or queue for audit/debugging. Keep:

• provider event id
• message id
• recipient
• event type
• timestamp
• payload
• processed status

This helps with retries and duplicate events.

5) Update your application state

Map events to your internal records. For example:

• delivered → mark message as delivered
• bounce → mark recipient as invalid or failed
• complained → suppress future sends
• clicked / opened → track engagement

Use the provider’s message identifier to relate the event back to the original email send.

6) Handle duplicates and ordering

Email providers often retry webhooks and may deliver events out of order. Make your handler:

• idempotent: ignore duplicate event IDs
• order-tolerant: don’t assume “opened” arrives after “delivered”
• state-aware: only advance status when appropriate

Example:

• if a message is already marked bounced, don’t overwrite it with delivered

7) Process asynchronously

For reliability, do minimal work in the webhook request:

1. verify and parse
2. enqueue event
3. return 200 OK

Then have a worker process the queue and update your database. This avoids timeouts and supports retries.

8) Log and monitor

Track:

• invalid signatures
• failed parses
• webhook retries
• queue backlog
• processing errors

Set alerts for spikes in bounces/complaints.

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Example flow

1. You send email with message_id = abc123
2. Provider later sends webhook:

   {
     "event_type": "delivered",
     "message_id": "abc123",
     "recipient": "user@example.com",
     "timestamp": "2026-09-23T12:34:56Z"
   }
   

3. Your webhook:
   • verifies signature
   • stores event
   • marks abc123 as delivered
   • returns 200 OK

---

Suggested database model

emails

• id
• provider_message_id
• recipient
• status
• sent_at
• delivered_at
• bounced_at

email_events

• id
• provider_event_id
• provider_message_id
• event_type
• payload
• created_at

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If you want a robust implementation

I can provide:

• a sample webhook handler in Node.js, Python, or Go
• a database schema
• event-processing logic for a specific provider like SendGrid, Mailgun, Amazon SES, or Postmark