Find out why a message landed in spam, arrived late or failed authentication. Paste the raw headers and get the delivery path hop by hop, the SPF, DKIM and DMARC verdicts with alignment, the DKIM signatures and the one-click unsubscribe headers Gmail and Yahoo require.
Runs 100% in your browser — nothing is uploaded
🔒 Private by design: the headers are analyzed in your browser and are never uploaded. Safe for confidential mail.
Alignment is checked in relaxed mode (same organizational domain as From). The receiver’s DMARC result is authoritative.
| # | From | By | Protocol | Time | Delay |
|---|
Rows in amber took over a minute, rows in red over five minutes. Lower hops are reported by the sender and can be forged.
Perfect SPF, DKIM and DMARC do not stop bounces. Sending to invalid, disposable or abandoned addresses hurts your sender reputation just as much. Validate your list before the next campaign.
Open the message in your mail client and use “Show original” or “View source” (instructions below the box). Copying the whole message is fine — we stop at the body.
The headers are parsed in your browser: folded lines are joined, encoded subjects decoded and the Received chain put in chronological order.
SPF, DKIM and DMARC come from the Authentication-Results header added by the receiving server, with relaxed alignment against the From domain.
Each hop shows its timestamp and the time since the previous one; slow hops are highlighted so you can see where mail got stuck.
Every server that handles a message adds headers on top. Reading them bottom-up tells the story of the delivery.
Each server adds a Received line with who it got the message from, its own name, the protocol and a timestamp. The bottom one is closest to the sender; the top one is your mailbox provider. Only the top hops are trustworthy — lower ones can be forged.
Added by the receiving server: spf=, dkim= and dmarc= results with the domains checked (smtp.mailfrom, header.d, header.from). ARC-Authentication-Results preserves earlier verdicts when mail is forwarded.
d= is the signing domain, s= the selector (the key lives at s._domainkey.d), a= the algorithm and h= the list of signed headers. DMARC needs a passing signature whose d= matches the From domain.
Gmail and Yahoo require bulk marketing mail to carry List-Unsubscribe with an https link plus List-Unsubscribe-Post: List-Unsubscribe=One-Click (RFC 8058), both covered by the DKIM signature.
No. The analyzer runs entirely in your browser — the text you paste is never sent to our servers or to anyone else. You can even disconnect from the internet after the page loads and it still works.
Open the message, click the three-dot menu next to Reply and choose “Show original”. Then use “Copy to clipboard” and paste it here.
In Outlook on the web or the new Outlook, open the message, click “…” › View › View message details. In classic Outlook for Windows, open the message and go to File › Properties; the headers are in “Internet headers”.
DMARC needs only one of SPF or DKIM to pass with alignment. Forwarded mail and many marketing platforms fail SPF alignment (their return-path is on another domain) but pass DMARC through an aligned DKIM signature. That is normal.
Look at the delay column: a large gap usually means greylisting (the receiver asked the sender to retry), a queue at the sending platform or a slow content filter. Negative delays are just clocks that disagree between servers.
Spam Confidence Level, set by Microsoft 365 and Outlook.com: -1 means trusted, 0–1 not spam, 5–6 spam and 7–9 high-confidence spam. It is found in X-MS-Exchange-Organization-SCL or in X-Forefront-Antispam-Report.
No. Senders can add fake Received or Authentication-Results lines below the real ones. That is why the analyzer reads the topmost Authentication-Results header — the one added by the server that delivered the message to the mailbox.
No — it only reads the headers you paste. To check a domain’s SPF, DKIM and DMARC records in DNS, use our free SPF, DKIM & DMARC checker.
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