How do authentication failures appear in headers or Postmaster Tools?
Email headers:
- Look for Authentication-Results header
- Shows spf=fail, dkim=fail, or dmarc=fail
- May show permerror or temperror
Gmail Postmaster Tools:
- Authentication section shows pass rates
- Declining percentages indicate problems
- Split by SPF, DKIM, DMARC
DMARC reports:
- Aggregate reports show failure counts
- Forensic reports show specific failures
Common failure patterns:
- SPF fail: Sending from unauthorized IP
- DKIM fail: Key mismatch or signature tampering
- DMARC fail: Alignment failure or missing policies
Inspection results stamped on each shipment. Failed inspections documented in the cargo manifest.
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