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Email Header Analyzer
Reads raw email headers and shows the delivery path with per-hop delays, the SPF, DKIM and DMARC results, and address mismatches.
Developer
Nothing uploaded
No sign-up
Free, unlimited
Gmail: Show original. Outlook: File → Properties → Internet headers.
Paste something on the left to see the result.
In short
Email headers are read from the bottom upwards: each server prepends its own Received: line, so the last one in the file is the first hop the message took. The Authentication-Results header records what the receiving server concluded about SPF, DKIM and DMARC. The detail worth understanding is that SPF authenticates the hidden Return-Path and DKIM authenticates a signing domain, and neither has to match the From address a person reads — only DMARC checks that link. A message can therefore pass SPF while showing any From address at all. Paste headers into the Email Header Analyzer on inputtesthub.com and it lists the hops with delays, the three authentication results, and any mismatch between From, Return-Path and Reply-To.
How to use the Email Header Analyzer
- Copy the full raw headers from your mail client.
- Paste them in.
- Read the hop table for delays and the authentication row for the verdict.
About the Email Header Analyzer
The Email Header Analyzer reads raw email headers and shows the delivery path with per-hop delays, the SPF, DKIM and DMARC results, and address mismatches. It runs as plain JavaScript inside the page, which means there is no upload step, no queue and no size limit imposed by a server — the only limit is your own device.
What people use it for
- Working out where a message was delayed.
- Checking whether a suspicious message really came from the domain it claims.
- Diagnosing why a message went to spam.
Details
| Received headers | Read bottom to top — the oldest hop is last |
|---|---|
| SPF authenticates | The Return-Path, not the visible From |
| DKIM authenticates | A signing domain, not necessarily the From |
| DMARC | The only one that requires alignment with the From |
| Trust | Only hops added by servers you control can be relied on |
The most common surprise in these results is a Return-Path on a different domain from the From. That is completely normal for a newsletter or a service sending on a client's behalf, and it is also exactly what a spoofed message looks like — which is why the DMARC line, not the SPF line, is the one to read first.
Where this tool stops
Reads what you paste. It cannot verify a DKIM signature — that needs the public key from DNS and the exact original message bytes — so the DKIM result shown is the receiving server's conclusion rather than an independent check.
Frequently asked questions
How do I get the raw headers?
In Gmail, open the message, use the three-dot menu and choose <b>Show original</b>. In Outlook desktop, open the message and go to <b>File → Properties → Internet headers</b>. In Apple Mail, <b>View → Message → All Headers</b>. Copy everything from the top down to the first blank line.
SPF passed, so is the message genuine?
Not necessarily, and this is the most useful thing to understand about email. SPF checks the <b>Return-Path</b>, which is invisible to the reader and can belong to any domain the sender controls. A message can pass SPF perfectly while displaying a From address of your bank. Only DMARC requires the authenticated domain to line up with the From that people actually see.
Which hop caused the delay?
The delay column shows the gap between each Received line and the one before it. A single large gap points at one server — usually greylisting, a queue, or a scanning appliance. Small gaps everywhere point at the message being large rather than at any one hop.
Can headers be faked?
Everything above the first server you control can be, because a sender can invent Received lines before handing the message over. Your own infrastructure's hops are trustworthy; the ones claiming to be earlier are only as honest as whoever wrote them.
Do I need an account to use the Email Header Analyzer?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the tool.
Is the Email Header Analyzer safe to use with private information?
No. The Email Header Analyzer runs entirely in your browser using JavaScript. Because the work happens locally, the tool also keeps working if your connection drops, and closing the tab is all it takes to discard everything.
What problem does the Email Header Analyzer solve?
In practice it gets used for three things: working out where a message was delayed. Checking whether a suspicious message really came from the domain it claims. Diagnosing why a message went to spam. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
When is the Email Header Analyzer not the right tool?
Reads what you paste. It cannot verify a DKIM signature — that needs the public key from DNS and the exact original message bytes — so the DKIM result shown is the receiving server's conclusion rather than an independent check. Knowing where a tool stops being trustworthy matters more than the cases where it works.
Which values should I know?
Received headers is Read bottom to top — the oldest hop is last. SPF authenticates is The Return-Path, not the visible From. DKIM authenticates is A signing domain, not necessarily the From. These are printed on the page itself, so you do not have to take them on trust.
Does the Email Header Analyzer work on a phone?
Yes. The page is responsive and the tool works in Chrome, Safari, Firefox, Edge and Samsung Internet on both Android and iOS. There is no app to install and nothing to sign into.
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