Decode the hidden metadata in every email to diagnose authentication failures, routing issues, and spam filter decisions.
⚡ Monitored by EmailExacto IntelligenceEmail headers are metadata fields at the top of every message recording its journey from sender to recipient. Each mail server that handled the message adds a Received: header, and authentication systems add verdicts in Authentication-Results:. Headers are invisible in normal email clients but contain a complete audit trail of every deliverability decision made about the message.
Key headers for deliverability diagnosis:
Authentication-Results (added by receiver) shows SPF, DKIM, and DMARC verdicts. Received-SPF shows detailed SPF result. X-Spam-Status shows spam score and triggered rules. Received: headers chain every hop with timestamps — delays between hops reveal queuing or reputation-based throttling.
Email headers are the definitive source of truth for diagnosing deliverability problems. Not sure DKIM is signing? Check Authentication-Results. Seeing delays? The Received chain shows exactly where the bottleneck is. Spam filters triggering? X-Spam headers reveal which rules fired. Every deliverability investigation should start here.
EmailExacto includes a built-in Email Header Analyzer that parses raw headers and surfaces authentication results, routing chain, and diagnostic signals.
✓Always analyse headers from the received message, not your sent copy.
✓Check Authentication-Results first — it summarises the authentication verdict in one place.
✓A dmarc=fail when spf=pass and dkim=pass usually means an alignment issue.
✓Use the Received chain timestamps to identify where delays occur.
✓Share full headers (not screenshots) when reporting issues to your ESP.
✓Look for X-Spam-Status or X-MS-Exchange-* headers to see filter verdicts.
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