What’s the difference between SMTP transcript vs event log?

• SMTP transcripts and event logs capture delivery information at different levels of detail.
• SMTP transcript:
• Raw protocol conversation between servers
• Shows every command and response
• Includes EHLO handshake, authentication, DATA transmission
• Contains exact error messages from receiving server
• Example snippet:
• 250-mail.example.com Hello
• 250-PIPELINING
• 250 OK
• RCPT TO:<user@example.com>
• 550 User not found
• Event log:
• High-level record of what happened
• Standardized events: sent, delivered, bounced, deferred, opened, clicked
• Timestamps and basic metadata
• Aggregated and normalized across many deliveries
• Example: "Message abc123 bounced at 2026-02-05 10:30:00 - User unknown"
• When to use which:
• Event logs: Normal monitoring, reporting, automation triggers, general troubleshooting

SMTP transcripts: Deep debugging when event logs don't explain the problem, understanding exact rejection reasons, diagnosing unusual server behavior

ESPs typically provide event logs through dashboards and APIs. SMTP transcripts may require special access or support requests. Self-hosted MTAs can log full transcripts if configured.