Analyze email headers
Paste the raw headers of a message. Get each server hop in order with the delay between them, SPF, DKIM and DMARC results, Return-Path and From alignment, Message-ID, List-Unsubscribe and why it might land in spam. Free, no account.
1 thing in these headers could send it to spam.
Example headers. Paste your own above.
Reading stopped at the first blank line, where the message body starts.
3 hops in 6 min 10 s; SPF pass, DKIM pass, DMARC pass; From domain example.com aligned.
Why it might land in spam
- Check 1 hop took over 5 minutes (slowest 6 min 8 s): mail can be queued or greylisted there.
- Note No List-Unsubscribe header. Google and Yahoo require one-click unsubscribe for bulk marketing mail; a one-to-one cold email does not need it.
Authentication
| Check | Result | Detail |
|---|---|---|
| SPF | pass | envelope domain example.com |
| DKIM | pass | d=example.com |
| DMARC | pass | policy p=quarantine |
Hops, oldest first
| # | From | By | With | Time | Delay |
|---|---|---|---|---|---|
| 1 | mail.example.com [192.0.2.10] | mx-relay.example.com | ESMTPSA | 2026-11-08 16:00:02 UTC | |
| 2 | mx-relay.example.com [192.0.2.25] | mx.google.com | ESMTPS | 2026-11-08 16:06:10 UTC | 6 min 8 s |
| 3 | — | 2002:a05:6a10:1f4e:b0:5d1:2c3a:9f01 | SMTP | 2026-11-08 16:06:12 UTC | 2 s |
Sender, alignment and list headers
- From
- sam@example.com
- Return-Path
- bounce@example.com
- SPF alignment
- aligned (relaxed)
- DKIM alignment
- aligned (relaxed)
- Reply-To
- none
- Message-ID
- <a1b2c3.d4e5@example.com>
- Message-ID domain
- example.com
- List-Unsubscribe
- none
- One-click unsubscribe
- no
- Subject
- Quick question about your website
- Date
- Sat, 8 Nov 2026 10:00:01 -0600
Read from the headers alone, with no network lookup. Mail providers also weigh the content, the sender's reputation and how recipients engage, which headers do not show. Alignment here is relaxed: the same registered domain, the way DMARC's default works.
How to get the raw headers
- Gmail: open the message, the three-dot menu, then Show original. Copy the text above the first blank line (or all of it; reading stops where the body starts).
- Outlook: open the message, then File, Properties (desktop) or View, View message details (web), and copy the Internet headers.
- Apple Mail: View, Message, All Headers, or Raw Source.
What it reads
- Received: every server that handled the message adds one at the top, so they are read bottom up: the oldest hop first, with the time between hops. Over 5 minutes is flagged; that cut-off is our rule of thumb. A hop that seems to go back in time is clock skew between servers.
- Authentication-Results (RFC 8601): the receiving server's SPF, DKIM and DMARC verdicts. Only the top one is trusted.
- Alignment: DMARC passes only when SPF's envelope domain or a passing DKIM signature's domain matches the From domain.
- Message-ID, Date and From: RFC 5322 requires Date and From and says every message should carry a Message-ID.
- List-Unsubscribe and one-click (RFC 8058), which Google, Email sender guidelines (checked 8 Nov 2026) and Yahoo, Sender best practices (checked 8 Nov 2026) require of bulk marketing mail.
- Spam filter stamps: X-Spam-Status and X-Spam-Flag (SpamAssassin) and Microsoft's SCL, where 5 or higher generally means filtering considered the message bad (Microsoft, Spam confidence level (checked 8 Nov 2026)).
Headers are parsed on the server for that one request: no lookup, no storage, and the result
page is not cached or indexed. For long headers the form posts them; short ones also work as
?q=.
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Fix what it finds
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Questions
Read the Received lines from the bottom up: each is one server handing the message on. Authentication-Results at the top shows whether SPF, DKIM and DMARC passed. Paste them above to have it laid out.
The headers show failed or missing SPF, DKIM or DMARC, a From domain that does not align, spam filter stamps and slow hops. Content, reputation and engagement also count, and do not show in headers.
The domain that passed SPF (the envelope sender) or DKIM (the d= domain) must match the domain in From. Without a match DMARC fails, even if SPF and DKIM pass for another domain.
No. They are parsed for the one request and not kept, and the result page is not cached.
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