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Email header analyzer.

Paste the raw headers from any email and read the whole delivery story - the Received hops in order, the delay at each stop and the total transit time, plus the SPF, DKIM and DMARC verdicts. Parsing happens right here in your browser; nothing is uploaded.

Parsing happens locally in your browser - nothing is uploaded.

What the headers tell you

Every email carries a stack of headers the mail servers add as it travels. Read together, they answer two practical questions:

How did it get here, and how fast?
The Received hops trace the exact path from the sender's server to the inbox. Timing the gaps between them shows where a message stalled - a slow hop is often greylisting or a backed-up queue, not a broken address.
Was it actually authenticated?
The SPF, DKIM and DMARC verdicts show whether the receiving server believed the message really came from its claimed domain. See the guide to SPF, DKIM and DMARC for what each check proves.

Using headers to debug deliverability

When a message lands in spam, the headers are the first place to look. A DKIM or DMARC failure, an unexpected relay in the Received chain, or a long stall between hops are all clues that point to a specific fix - and most of them trace back to authentication or list quality rather than the content itself. The rundown of why emails go to spam walks through the common causes and how the headers reveal them.

Email header analyzer FAQ

In Gmail, open the message, click the three-dot menu and choose 'Show original'. In Outlook, open the message and use File → Properties (or 'View message source'). In Apple Mail, use View → Message → Raw Source. Each shows the full header block - copy everything from the top down to the first blank line and paste it in.

Each Received header records one server handing the message to the next. They're stored newest-first, so this tool reverses them into delivery order: hop 1 is where the message entered the mail system and the last hop is the server that delivered it. The delay column shows the gap between consecutive hops - a large jump usually means greylisting or a queue backlog rather than a real delivery problem.

They're the receiving server's authentication checks, taken from the Authentication-Results header. 'pass' means the mechanism validated, 'fail' or 'softfail' means it didn't, and 'none' means no policy was published. DKIM can also carry its own DKIM-Signature header, which this tool flags separately. A message that fails SPF and DKIM alignment under DMARC is far more likely to be filtered.

Yes. The analyzer runs entirely in your browser - there is no server call and nothing is uploaded or stored. The headers never leave your device, so you can safely inspect messages that contain internal server names or routing details.

Fix the addresses before they bounce

Headers explain a delivery after the fact - verification stops the bad ones first. Clean your list to remove invalid and dead addresses before you send; start free with 100 credits, no card required.

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