Message Header Analyzer
Paste email headers to see the delivery path, delays, SPF/DKIM/DMARC results and Microsoft 365 spam verdicts.
Processed locally in your browser
In Outlook: open the message → File → Properties → Internet headers (classic) or … → View → View message source (new Outlook, Outlook on the web). A complete .eml file works too – the body is ignored.
About this tool
Message headers record how an email travelled and how it was checked. This analyzer turns them into a readable report: delivery path with the delay at each hop, email authentication (SPF, DKIM, DMARC and Microsoft’s composite authentication with its reason code) and the Microsoft 365 filtering verdict from the X-Forefront-Antispam-Report and X-Microsoft-Antispam headers.
The meanings of CAT, SFV, IPV, SFTY, BCL and the compauth reason codes follow Microsoft’s anti-spam message headers documentation. Note that in Microsoft 365 the SCL value no longer decides whether a message is spam – the category (CAT) and verdict (SFV) do.
Headers contain names, email addresses and IP addresses. Everything is analyzed locally in your browser; nothing is uploaded or stored.
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