What logs or headers should be collected during diagnosis?

Email headers:

• Authentication-Results (SPF, DKIM, DMARC)
• Received headers (routing path)
• X-headers from ESP or filters

SMTP logs:

• Connection status and errors
• Response codes from receivers
• Timing and throughput data

Bounce logs:

• Error codes and messages
• Receiving server responses
• Timestamp correlation

Sending records:

• Campaign details (time, volume, segment)
• List source information
• Content that was sent

External data:

• Postmaster tool screenshots
• Blocklist check results
• Third-party reputation scores
• Comprehensive data enables accurate diagnosis.

Ship logs, cargo manifests, port records, and inspection reports all tell part of the story.