Email Tools

Email Header Analyzer

Paste an email's raw headers to trace its route and read its authentication results.

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Paste raw email headers

Analyzed entirely in your browser - headers are never sent anywhere.

Not sure what to enter?

Paste the full headers of an email to see each server it passed through, how long each hop took and whether SPF, DKIM and DMARC passed.

How do I read email headers?

Email headers record every server a message passed through (the Received lines, read from bottom to top) and the results of SPF, DKIM and DMARC checks. Paste the raw headers above and this analyzer lays out the delivery hops and authentication results - it runs in your browser.

How to analyze email headers

Open the message in your email client and copy its full headers (in Gmail: More > Show original).
Paste them into the box above.
Click Analyze Headers.
Check the SPF, DKIM and DMARC results and look for unusually slow hops in the delivery path.

Related checks

If DKIM failed, check the key with the DKIM Checker.
If SPF failed, check the record with the SPF Checker.

Paste the complete raw headers - "Show original" in Gmail, or "View source" in Outlook and Apple Mail - not just the From and Subject lines. Each mail server that handles a message adds its own Received line at the top, so reading them from bottom to top traces the route from the sender to your inbox and shows where a delay happened. The analyzer also reads the Authentication-Results header to show whether SPF, DKIM and DMARC passed; a fail usually means the message came from a server the domain has not authorized, or was altered in transit. JustChecker builds tools that respect your data - this one never leaves your browser.

Frequently Asked Questions

In Gmail open the message, click the three-dot menu and choose "Show original". In Outlook open the message, then File > Properties (desktop) or View message source (web).

Look for SPF, DKIM or DMARC failures, a From domain that differs from the Return-Path, and first hops from servers unrelated to the claimed sender.

No. The analysis runs in your browser and the headers are not sent to our servers.

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