Paste a raw header block and this free email header analyzer shows SPF, DKIM, and DMARC verdicts, the full delivery path, and every key header field. Parse email headers online free, in your browser — no header text is uploaded anywhere.
Every email message contains two parts: the visible body (the text, images, and HTML you read) and the technical headers that live above the body. Headers record the full routing history of the message, authentication results, spam scores, and metadata like the sender, recipient, subject, and timestamps. Most email clients hide headers from normal view, but they are always present and can be revealed through your mail client's "show original" or "view headers" option.
Analyzing email headers is one of the most reliable ways to diagnose delivery problems, investigate suspected phishing messages, and verify that your authentication setup (SPF, DKIM, DMARC) is working correctly for a real message.
Copy everything from the first header line (usually Delivered-To: or Return-Path:) down to the blank line before the email body.
The most important headers for diagnosing delivery issues are:
A message showing spf=pass dkim=pass dmarc=pass in the Authentication-Results header has the best chance of inbox placement. Any failure here should be investigated. An SPF failure often means the sending IP is not listed in your SPF record. A DKIM failure may mean the signature is missing, expired, or the public key in DNS does not match the private key used for signing. A DMARC failure means neither SPF nor DKIM aligned with the From domain.
Header analysis tells you what happened with a specific message. To prevent problems before sending, use email verification on your list and verify your authentication configuration with our SPF, DKIM, and DMARC generator tools. For large lists, bulk verification and the validation API let you integrate checks into your workflow.
What a header holds
Every message carries a header block the recipient never sees. A free email header analyzer parses that header into the fields that actually explain what happened to the message.
Each server that handles a message prepends its own Received header, so the chain reads bottom-up: the oldest hop is last. The email header analyzer reverses it into chronological order, which is the only way to read a delay.
Timestamps on each Received header show where a message sat. A twelve-hour gap between two hops is a queue, not a network problem, and the header analyzer surfaces it immediately.
The receiving server writes its own conclusions into this header. A free email header analyzer reads them back rather than re-running the checks, because the receiver's verdict is the one that decided delivery.
This is the single most useful header for diagnosing spoofing and deliverability. Three verdicts, one header, and the header analyzer separates them so a DKIM pass is never mistaken for a DMARC pass.
The Return-Path header is the envelope sender that SPF authorises. The From header is what the recipient sees. When the two headers disagree, DMARC alignment decides whether that is legitimate forwarding or a spoof.
An email header analyzer that shows both header fields side by side makes the mismatch obvious in a second, where reading a raw header takes minutes.
The Message-ID header uniquely identifies the message and is what a provider's support team will ask for. The Date header is the sender's claim, not the delivery time — the Received header chain has the truth.
Filter scores such as the X-Spam-Status header appear when the receiver adds them. The header analyzer surfaces whichever header the receiving system wrote.
Reading verdicts
Four combinations cover almost everything a free email header analyzer will show you in the Authentication-Results header.
Fully authenticated and aligned. If this message still landed in spam, authentication is not the cause — look at content, reputation, and complaint history.
This is what a healthy header looks like in the email header analyzer, and it is worth running one of your own sends through to learn the shape.
The normal signature of forwarded mail. Forwarding rewrites the delivering IP so SPF fails, while the DKIM signature survives intact and carries the DMARC alignment.
Not a problem. An email header analyzer that flagged this combination as a failure would be misleading you.
Usually a message modified in transit — a mailing list appending a footer, or a security appliance rewriting links. The signature no longer matches the body.
Alignment still holds through SPF, so delivery is fine. Worth investigating in the free email header analyzer if it happens on every send.
Neither SPF nor DKIM produced an aligned pass. Under an enforcing policy the message is quarantined or rejected outright.
Read the Authentication-Results header the email header analyzer extracted, find which mechanism failed, and fix that record on the sending side.
Using it
The header analyzer answers questions nothing else can, and it answers them from a header you already have.
Read the Received header chain bottom-up and look at the gaps between timestamps. The hop where the time jumps is the one that queued the message, and only the header records it.
Nothing else tells you this. Delivery logs on your side end at handoff; the header carries the rest of the journey.
Compare the Return-Path header against the From header, then read the DMARC verdict. Those two header checks settle most suspicious messages in under a minute.
The free email header analyzer only covers the message that arrived. For the sender address itself, use Is This Email Legit to confirm whether a working mailbox is behind it.
Send a message to an account elsewhere, then parse email headers online free from the copy that arrived. The receiver's own header verdicts are more useful than any prediction.
If the header analyzer shows authentication passing cleanly, the problem is content or reputation rather than configuration.
Providers ask for the Message-ID header before they will look at anything. The email header analyzer extracts that header without you scrolling through raw text.
Copy it exactly from the email header analyzer, including the angle brackets.
Limits
A header is a record of what happened, not a prediction and not proof of identity.
Any header a sender writes can be faked. Only the Received header lines added by servers you trust are reliable, which means reading the header chain upward from the receiving end.
A free email header analyzer shows the whole chain; judging where trust begins in that header is still your job.
The header analyzer reads one message that already arrived. A header cannot tell you whether your SPF record is under the ten-lookup limit or your DMARC policy is set correctly.
For that, use the sender-side checkers rather than an email header analyzer — a header is evidence about one message, not about your configuration.
Large mailbox providers rarely explain a spam-folder placement in the header. An absent header explanation is not evidence that nothing happened.
Postmaster tools from the provider are the only visibility into that layer.
Parsing a header tells you about one delivered message. Whether the addresses on your list exist is a different question no header answers.
For that, use Email Verifier; a clean header and a dead recipient address are entirely compatible.
Reference
Header syntax is defined by the IETF, and the tools beside this free email header analyzer cover the sender side.
The IETF's RFC 5322 defines the header field syntax every email header analyzer parses, including Received, From, and Message-ID.
Authentication-Results is defined separately in RFC 8601, which is why a header analyzer treats it as its own section.
A header shows a receiver's verdict. The SPF Checker and DMARC checker show whether your own records are configured to earn a pass.
Parse email headers online free to see what happened; use those tools to change what happens next.
Authentication is half the job. Bulk Email Verification removes the dead addresses that damage sending reputation regardless of how clean your headers are.
A free email header analyzer and a verified list solve the two halves of the same deliverability problem.
No. The email header analyzer runs entirely in your browser. The header text you paste never leaves the page, which is why you can parse email headers online free without an account and without worrying about what the header contains.
Open the message, use the three-dot menu, and choose Show original. Copy the header block from the top of that view and paste it into the email header analyzer. Outlook calls the same view message details, and the header analyzer accepts either format.
Usually not. That combination is the normal signature of forwarded mail: forwarding rewrites the delivering IP so SPF fails, while the DKIM signature survives and carries DMARC alignment. A free email header analyzer that flagged it as a failure would be misleading you.
Each server that handles the message prepends its own Received header. The header chain reads bottom-up, oldest last. Our email header analyzer reverses the header order into chronological sequence so you can see where the message actually waited.
It uniquely identifies the message and it is the first thing a provider's support team will ask for. The email header analyzer extracts it so you do not have to scroll through raw header text looking for it.
DMARC fail means neither SPF nor DKIM produced an aligned pass. Read the Authentication-Results header the email header analyzer extracted, identify which mechanism failed, then fix that record on the sending side with the SPF or DMARC checker.
Nineteen free tools alongside the paid AI features, none of them requiring an account.
Email Tools
Free email deliverability test: send one message and get authentication, DNS, spam-filter, blacklist, header, and content scores. A free email inbox placement test, no signup.
Sender or message diagnostics — not address discovery.
Email Tools
Free email bounce rate calculator: work out your hard and soft bounce rates, and check acceptable email bounce rate thresholds against published benchmarks.
Email Tools
Free reverse email lookup: start from an address and see the domain, organisation, mail routing, role-account pattern, and any public profile. Find email owner for free.
Email Verify Tools
Check if an email address is valid with a free email verifier, no signup — syntax, MX, SMTP mailbox, disposable, role and catch-all checks.
Recipient evidence — not sender or DNS configuration.
Free Tools
Free DNS record lookup for any domain: A, AAAA, MX, TXT, NS, CNAME, SOA resolved live from authoritative nameservers. DNS record lookup tool, free, no signup.
Domain or infrastructure evidence — not mailbox proof.
Email Verify Tools
Email list cleaning service with live SMTP verification on every row: dedupe, suppress hard bounces, keep the reasons. Clean email list free tool, no signup to try.
A header explains one delivered message. Invalid addresses cause bounces no header analyzer can fix — parse email headers online free here, then verify the list.
Parse email headers online free · Header analyzer runs in-browser · SPF, DKIM, DMARC header verdicts · Header analyzer, no account
