Email Header Analyzer
Reads the SPF, DKIM and DMARC results your inbox recorded for one message, and whether each aligns with the From: domain. Runs in your browser.
@emailens/engine 0.18.22 · data last changed 10 Nov 2026
Your headers are read in your browser and never leave your device. Only the sending server's IP and HELO name are sent, for the DNS lookup.
Passing SPF, DKIM and DMARC gets the email delivered; it still has to look right once it arrives. Open the checker and paste its HTML: five clients, no account.
No signup · Five clients free, Outlook Classic included · All 21 with an account
Which clients need an account
Gmail Android, Gmail iOS, Outlook 365, Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail, AOL Mail, Fastmail, Superhuman open with a free account.
The checker needs a computer screen.
Your next question
- Is the sending domain set up right? Check your domain, free.
- Is anyone sending as your domain? Read your DMARC report, free.
Other free tools: SPF Record Checker · DKIM Checker · DMARC Checker · BIMI Checker · Blocklist Checker · DMARC Record Generator · Email Spam Checker
Run this check on every email
SPF, DKIM and DMARC monitoring (Dev). Dev is $9 a month. Share links for your client's sign-off, a test inbox and an API key. See the plans →
Questions
How do I get the raw email headers?
In Gmail, open the message, click the three-dot menu and choose 'Show original'. In Apple Mail, use View → Message → All Headers. In Outlook, open the message and go to File → Properties, then copy the Internet headers. Paste the whole block here, everything above the first blank line.
What's the difference between authentication and alignment?
Authentication asks 'did SPF or DKIM verify?' Alignment asks 'does the verified domain match the visible From: address?' DMARC only counts a mechanism when it does both. That's why a message can show spf=pass but still fail DMARC. The SPF domain didn't align with From:.
Why does SPF pass but not align?
Most email services send with a Return-Path on their own subdomain (like bounces@mail.acme.com), so SPF authenticates that domain. If it doesn't share your From: organizational domain, SPF won't align, and DKIM alignment has to carry DMARC instead. This is normal, as long as DKIM is aligned.
Is my email private?
Yes. The headers are parsed entirely in your browser with JavaScript. Nothing is uploaded or sent to a server. You can verify this by going offline and running the tool.