Header Analysis

Email Header Analyzer Guide: Read SPF, DKIM, DMARC, and Spam Signals

Raw headers show what the receiving mail server actually saw. Learn where to find Authentication-Results, how to read the Received chain, how From, Return-Path, and Reply-To alignment affects trust, and which header signals explain a message that lands in Junk instead of the inbox.

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Read the receiving hop, not just the sending configuration

Start with the last Authentication-Results header added by the receiving provider. It records the SPF, DKIM, and DMARC verdicts at the hop that made the placement decision, which can differ from a local DNS check or the sending platform's dashboard.

Then compare the visible From domain with the DKIM d= domain and Return-Path. Follow the Received chain for unexpected relays, and inspect Reply-To for a different root domain or another phishing-shaped mismatch. The free analyzer turns those raw fields into a readable verdict and a 0–100 spam-likelihood score.

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Next steps

Related resources

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Check a sending domain against DNS blocklists

Run a free, point-in-time lookup and review which configured providers report a listing, return a clean result, or are unavailable. No account is required.

Results cover only the configured DNS blocklists that return a usable response. A clean result does not cover every blocklist or establish inbox placement; an unavailable provider remains unchecked.

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Make the receiving verdict explainable

Paste the raw headers from Gmail, Outlook, or Apple Mail into the free analyzer and see the authentication and spam signals in one report.

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