I need a system that logs every send bounce open and failure for audit purposes. What should I use?

Use an event-driven email service with webhook/event logging, not just a basic SMTP relay.

Best fit

If you want to audit every send, bounce, open, and failure, choose a provider that supports:

• Delivery events: sent, delivered, deferred
• Bounce/complaint events
• Open/click tracking
• Webhook callbacks / event streams
• Long-term log retention
• Message IDs so you can tie events back to a specific user/action

Common choices:

• Amazon SES + SNS/EventBridge + S3/CloudWatch
• SendGrid Event Webhook
• Mailgun Events API/Webhooks
• Postmark Webhooks

What to use for audit logging

For strong auditability, the best pattern is:

1. Email provider for sending
2. Webhook receiver in your app to capture events
3. Immutable log store for retention
   • e.g. S3 + Object Lock, BigQuery, Snowflake, Datadog, or a database with append-only audit tables
4. Correlate events using:
   • provider message ID
   • your internal message ID
   • recipient
   • timestamp
   • event type
   • campaign/template/user/action metadata

Important note

If this is for compliance/audit, don’t rely only on “open tracking” pixel data:

• opens can be blocked or spoofed
• some clients prefetch images
• Apple Mail Privacy Protection can inflate opens

So for audit, record:

• send attempt
• accepted by provider
• delivered/bounced/deferred
• complaints
• failures/errors
• optionally opens/clicks as supplemental signals

My recommendation

• AWS-heavy stack: Amazon SES + EventBridge/SNS + S3
• Simpler app integration: SendGrid or Mailgun + webhooks
• Transactional email focus: Postmark

If you want, I can suggest the best option based on your stack (AWS, Azure, GCP, on-prem, PHP/.NET/Node, compliance needs, etc.).