Live Tool

Header Analyzer

Paste raw email headers to extract sender identity, authentication outcomes, and a simple view of the routing path.

Email headers can contain personal data, internal hostnames, IP addresses, and routing information. Only paste headers you are authorised to analyse.

Maximum input size: 100 KB.

How this lookup works

Email headers often contain the fastest clues for sender authentication and routing investigations.

What it checks

  • Authentication-Results, Received-SPF, and DKIM-related headers where present.
  • Sender-related fields such as From, Return-Path, Reply-To, and Message-ID.
  • Received headers to estimate visible mail hop count.

Why it matters

  • Authentication failures often explain spam placement, rejection, or spoofing alerts.
  • Domain mismatches can point to forwarding, third-party platforms, or impersonation.
  • Long or unusual routing paths can highlight relay, forwarding, or delivery issues.

Common issues

  • Missing or partial authentication data.
  • From and Return-Path domains that do not align.
  • SPF, DKIM, or DMARC failures visible in Authentication-Results.

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