Email header analyzer
Paste the headers of an email you received to see every server it went through, how long each step took, and whether it passed SPF, DKIM and DMARC. The analysis runs in your browser: nothing is sent or saved.
Nothing is sent: your browser reads the headers, and they are gone when you close the page.
Checking a whole list?
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How it works
Where to find the headers
In Gmail, open the message, click the three dots and choose "Show original". In Outlook on the web, open the message, then the three dots, View, View message source. Copy everything above the message text.
What the analyzer reads
The Received lines give each server and the time the message reached it. Authentication-Results holds the receiver's SPF, DKIM and DMARC verdict. DKIM-Signature and List-Unsubscribe show how the sender signed the message and how people can leave the list.
Your data stays with you
Headers contain addresses, names and IP addresses. Only your browser reads them: nothing is sent to MailQuell or stored, and closing the page erases them.
Questions
Why is there no SPF, DKIM or DMARC result?
The receiving server writes these results when the message arrives. Paste the headers of a message you received, not the copy in your Sent folder.
What does "DKIM passes only for another domain" mean?
The message was signed by the sending service (for example your newsletter tool), but not with your own domain. DMARC then depends on SPF alone. Set up DKIM for your domain in that service.
Why did one step take so long?
A long delay between two servers usually means the message waited in a queue: the receiving server deferred it (greylisting, rate limits) or the sending server was busy. Clocks that are not set right can also show odd delays.
Is anything sent to your servers?
No. The analysis runs entirely in your browser. To check the DNS records of a domain, use the SPF and DMARC checker or the DKIM checker.
Related guides
- Email Headers: How to Read Them, Line by LineWhat email headers are, how to open them in Gmail and Outlook, and how to read the Received, Authentication-Results, DKIM and Return-Path lines.
- DMARC Fail: What It Means and How to Fix ItDMARC fails when neither SPF nor DKIM passes for your From domain. The usual causes (sending tools, forwarding, subdomains) and how to find yours.
- 550 5.7.26: Gmail \"Sender Is Unauthenticated\" Error and How to Fix ItGmail returns 550 5.7.26 when your message fails authentication. What it means, the DMARC variant, and the SPF, DKIM and DMARC fixes that make it go away.
- 421 4.7.28 and 421 4.7.0: Gmail Temporarily Deferred or Rate Limited Your Email421 4.7.28 means Gmail saw an unusual rate of unwanted mail from you and slowed you down. What triggers it, what 421 4.7.0 means, and how to recover.