Authentication-Results
Parse SPF, DKIM, and DMARC outcomes from receiver evaluation blocks.
Free tools
Email header analyzer — SPF, DKIM, DMARC & routing
Paste raw email headers from View original or Show headers to parse Authentication-Results, DKIM signatures, Received hops, delays, and delivery troubleshooting signals.
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At a glance
- What it is
- Raw header parser for Authentication-Results, DKIM signatures, Received hop timeline, and key message metadata.
- Who it is for
- Deliverability specialists, support teams, and MailFleet users troubleshooting authentication failures.
- Main capabilities
- SPF/DKIM/DMARC summary, hop delays, DKIM d=/s=, key headers, sample loader, captcha, rate limits.
- Platforms
- Browser-based header analysis on mailfleet.app. Headers are processed per request and not stored.
- Responsible use
- Paste headers from messages you are authorized to analyze. Do not include large message bodies.
Email header analyzer
Parse Authentication-Results, DKIM signatures, and Received hops from raw headers — headers only, not the body.
Capabilities
Decode headers in seconds
See exactly how receivers evaluated authentication and how your message routed across the internet.
DKIM signatures
Extract signing domain, selector, algorithm, and signed header list.
Received hop timeline
Visualize the mail path and delays between MTA hops.
Key headers
From, To, Subject, Date, Message-ID, Return-Path, List-Unsubscribe.
Delay analysis
Flag unusually long gaps between Received timestamps.
Abuse-resistant
Image captcha, session verification, and per-IP rate limits for public use.
How to use
Five steps to read your headers
- 1
Copy raw headers
Gmail: Show original. Outlook: View message details. Copy everything before the blank line.
- 2
Paste & captcha
Paste headers only — not the HTML body. Complete the captcha challenge.
- 3
Review auth summary
Check SPF, DKIM, and DMARC pass/fail from Authentication-Results.
- 4
Trace hops
Follow the Received chain from origin to final delivery MTA.
- 5
Fix & re-send
Update DNS or provider settings, re-send a test, and analyze again.
What are email headers?
Email headers are metadata added by each mail server along the delivery path. They include routing (Received), authentication (Authentication-Results, DKIM-Signature), and message identity (From, Subject, Message-ID).
Receivers evaluate SPF, DKIM, and DMARC at delivery time and record results in Authentication-Results — the fastest way to see how your message was judged.
How to read authentication results
spf=pass means the sending IP was authorized for the envelope domain. dkim=pass means the signature verified. dmarc=pass means alignment and policy succeeded — the gold standard for bulk mail.
A message can pass SPF and DKIM individually but fail DMARC if the signing or envelope domain does not align with the visible From address.
- spf=fail — sending IP not in SPF or wrong envelope domain
- dkim=fail — signature invalid, wrong selector, or body altered
- dmarc=fail — alignment or policy failure despite partial passes
What this tool does not do
Parsing is local to the pasted text — forwarded messages may show intermediate hops that differ from the original send path.
Paste headers only. Large bodies are rejected. This tool does not store or transmit your message content beyond the analysis request.
Key takeaways
- Paste headers only — stop before the message body blank line.
- Authentication-Results shows how the receiver judged SPF, DKIM, and DMARC.
- DMARC can fail even when SPF and DKIM pass individually — check alignment.
- Use the Received chain to spot delays and unexpected routing hops.
For regulatory context on commercial email in the United States, see the FTC CAN-SPAM compliance guide.
Delivery note: MailFleet helps users manage campaigns through their own sending providers. Delivery outcomes depend on sender reputation, DNS authentication, content quality, recipient engagement, list quality, provider rules, and mailbox filtering systems.
Email header analyzer FAQ
Gmail: open message → three dots → Show original. Outlook: open message → File → Properties → Internet headers.
Get started
Correlate headers with MailFleet campaign logs
Desktop sending with per-message provider responses and exportable logs for deliverability work.
Available on
- Windows 10+
- macOS 12+
- Linux (DEB & RPM)
Same desktop experience across every platform — one workflow for your entire team.