To track opens, clicks, bounces, and complaints for app email, you generally need to combine:

1. Email service/provider event tracking
2. Web/app analytics
3. Suppression and feedback-loop handling
4. Proper link and pixel instrumentation

Here’s the practical breakdown:

1) Track opens

How it works:
Add a tiny invisible image pixel to each email. When the recipient opens the email and images load, the pixel request is recorded as an “open.”

Implementation options:

• Use your ESP’s built-in open tracking
• Or embed a unique tracking pixel URL per message

Notes:

• Open tracking is imperfect:
  • Image blocking can prevent tracking
  • Apple Mail Privacy Protection can create inflated/uncertain opens
• Treat opens as a directional metric, not a ground truth

2) Track clicks

How it works:
Replace links in the email with tracked redirect URLs. When the user clicks, the tracking service logs the click and then forwards them to the destination.

Implementation options:

• ESP click tracking
• Custom redirect service
• Add UTM parameters for downstream analytics

Best practice:

• Use unique link IDs per campaign/message
• Include UTM tags so clicks can be attributed in analytics tools too

3) Track bounces

How it works:
A bounce happens when the receiving mail server rejects or can’t deliver the email.

Types:

• Hard bounce: permanent failure, e.g. invalid address
• Soft bounce: temporary failure, e.g. mailbox full or server issue

How to track:

• Most ESPs capture SMTP bounce responses automatically
• Subscribe to webhook/events from your ESP:
  • bounce
  • delivery
  • deferred
  • dropped

What to do with them:

• Immediately suppress hard bounces
• Retry soft bounces according to your provider’s rules
• Record bounce reason codes for analysis

4) Track complaints

How it works:
Complaints are usually generated when a recipient marks your email as spam.

How to track:

• Use ESP complaint events/webhooks
• Register for ISP feedback loops where available
• Monitor provider-specific spam complaint notifications

Important:

• Complaints should trigger immediate suppression
• Keep complaint rates very low to protect deliverability

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Recommended setup

If you use an ESP like SendGrid, SES, Mailgun, Postmark, etc.

Enable their event webhooks for:

• open
• click
• bounce
• complaint
• delivered
• deferred
• unsubscribe

Then store those events in your database or analytics pipeline.

Typical event flow

1. Your app sends an email through the ESP
2. ESP returns a message ID
3. You store that ID against the recipient/campaign
4. ESP sends event webhooks as things happen
5. You ingest, dedupe, and aggregate those events in your system

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Data model you’ll want

At minimum, store:

• message_id
• user_id
• campaign_id
• recipient_email
• event_type (open, click, bounce, complaint)
• timestamp
• link_url or link_id for clicks
• bounce_type / reason
• user_agent / ip if needed for diagnostics

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Metrics to calculate

• Delivered rate = delivered / sent
• Open rate = unique opens / delivered
• Click-through rate (CTR) = unique clicks / delivered
• Click-to-open rate (CTOR) = unique clicks / unique opens
• Bounce rate = bounces / sent
• Complaint rate = complaints / delivered

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Important caveats

• Opens are less reliable than clicks/bounces/complaints
• Clicks are more trustworthy and more actionable
• Complaints and bounces are essential for deliverability management
• Respect privacy/legal requirements (CAN-SPAM, GDPR, etc.)

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Best practice summary

If you want a solid implementation:

• Use your ESP’s webhooks
• Store per-message IDs
• Add tracking pixel for opens
• Use redirect links for clicks
• Ingest bounce/complaint events
• Build suppression lists and dashboard metrics

If you want, I can also show you:

• a sample architecture
• SQL schema
• Node/Python example for tracking these events
• setup instructions for a specific provider like SES, SendGrid, Mailgun, or Postmark