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Authenticate any email 100% client-side · headers never leave your browser

Header Forensics

Paste raw headers from any email client. We unfold MIME, extract Authentication-Results, parse every Received hop, and surface SPF / DKIM / DMARC verdicts. Find out exactly why a campaign hit spam - or didn't.

paste headers · analyze locally
or drag & drop a .eml file anywhere on this box
Headers stay in your browser · nothing uploaded
+How to find raw headers

Three clicks in any client.
Then paste.

/ Gmail
Gmail web
Open the message → click ⋮ menu top-right → "Show original" → Copy the headers panel at the top.
/ Outlook
Outlook 365
Open the message → File → Properties → "Internet headers" textarea at the bottom.
/ Apple Mail
Apple Mail
Select message → View → Message → All Headers (⌥⌘U) → Copy the displayed text.
+Headers tell the truth

The headers tell the full story.
You just need the right reader.

Auth-Results, hop chains, X-Spam-Score - exposed in plain English. Useful for debugging spoofing reports, deliverability complaints, and campaign delivery issues.

Continue learning
What Is Email Deliverability?The plain-English foundation, start here.Read guide → Why Your Emails Go to SpamThe most common causes, and how to fix each.Read guide → Why Transactional Emails Hit SpamA developer’s guide to inbox placement.Read guide →