Free tool / Header analyzer
Why did this email go to spam?
Paste the headers of one message. You’ll see how the receiving server judged it, which servers it passed through and how long each took, and what to fix — in plain words.
Analysed in your browser. Nothing you paste is sent anywhere.
Where to find the headers
- Gmail
- Open the message → ⋮ (More) → Show original → Copy to clipboard.
- Outlook (web)
- Open the message → … (More actions) → View → View message source.
- Outlook (Windows)
- Open the message in its own window → File → Properties → Internet headers.
- Apple Mail
- Open the message → View → Message → All Headers (or Raw Source).
- Yahoo Mail
- Open the message → … (More) → View raw message.
- Thunderbird
- Open the message → More → View Source (Ctrl+U).
Headers show what happened to one message. To check the settings behind all your mail, run the inbox check on your domain.
Questions people ask
Is it safe to paste email headers here?
Yes. The analysis runs entirely in your browser: the text is never uploaded, stored or logged. Headers contain addresses and server names but not the message body; if you paste a whole message, only the header section is read.
What does “DMARC fail” mean in email headers?
Neither SPF nor DKIM proved that the message comes from the domain in its From address. Genuine senders see this when a sending service isn’t set up for their domain; forged mail fails it by design. The sender’s DMARC policy decides what the inbox does: p=none delivers, p=quarantine sends to spam, p=reject refuses.
SPF and DKIM pass, so why did DMARC fail?
Because they passed for another domain. DMARC needs alignment: the SPF domain (the bounce address) or the DKIM signing domain (d=) must match the From domain. Newsletter tools often sign with their own domain until you turn on DKIM for yours.
What is SCL in Outlook headers?
The spam confidence level Microsoft assigns, from −1 (skipped filtering) to 9. Messages at 5 or above go to Junk; 9 is high-confidence spam. It appears in X-MS-Exchange-Organization-SCL and in X-Forefront-Antispam-Report.