How should I log emails sent by my application?

A good rule is: log enough to trace and diagnose, but never log the full email content or sensitive recipient data by default.

What to log

For each sent email, log a structured event with:

• Timestamp
• Message ID from your email provider
• Internal correlation ID / request ID
• Template name or email type (password_reset, invoice, etc.)
• Recipient identifier
  • Prefer a user ID or hashed email
  • If you need the address, restrict it to secured/debug logs
• Delivery status
  • queued / sent / deferred / bounced / failed
• Provider response / error code
• Retry count
• Tenant/account ID if applicable

Example:

{
  "event": "email_sent",
  "timestamp": "2026-09-23T10:15:00Z",
  "request_id": "req_12345",
  "message_id": "abcde-12345",
  "email_type": "password_reset",
  "recipient_user_id": "u_789",
  "recipient_email_hash": "sha256:...",
  "status": "sent",
  "provider": "ses",
  "provider_response_code": 250
}

What not to log

Avoid logging:

• Full email body
• Subject lines if they may reveal sensitive info
• Attachments
• Tokens, links, or passwords reset URLs
• Raw recipient addresses in general logs
• CC/BCC lists unless absolutely necessary and protected

Security and privacy tips

• Treat email logs as potentially sensitive data
• Use structured logs so you can filter and search safely
• Separate operational logs from debug logs
• Redact or hash addresses when possible
• Set retention limits and access controls
• Consider compliance requirements like GDPR/CCPA/HIPAA depending on your domain

For troubleshooting failures

When an email fails, log:

• Error category: validation, provider rejected, timeout, auth failure, rate limit
• Provider error code/message
• Retry/backoff details

Example:

{
  "event": "email_failed",
  "request_id": "req_12345",
  "email_type": "invoice",
  "recipient_user_id": "u_789",
  "status": "failed",
  "error_type": "provider_timeout",
  "provider": "sendgrid",
  "retry_attempt": 2
}

Practical recommendation

Best practice is:

1. Store the full email content in your database only if needed for business reasons, not in logs.
2. Log metadata only in application logs.
3. Use a separate secure audit trail if you must keep a record of exactly what was sent.

If you want, I can also give you:

• a recommended logging schema
• examples for Python / Node / Java
• guidance for GDPR-safe email logging