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Email Header Analyzer

Read an email’s journey, find the slow hop, and check SPF, DKIM and DMARC.

  • Free
  • No signup
  • Nothing uploaded
  • No watermark

Gmail: ⋮ → Show original. Outlook: File → Properties. Apple Mail: View → Message → All Headers.

Replies would go to totally-different.com, not sender.com. This is the single commonest trick in business email compromise.

At least one authentication check failed. Treat the sender address as unverified.

The longest delay was 900s at hop 2 (mx.google.com). A delay near 900s is usually greylisting — the receiving server deliberately deferring a first-time sender.

SPF

pass

Did the sending server have permission to send for that domain?

DKIM

pass

Was the message signed by the domain, and is the signature intact?

DMARC

fail

Does the domain’s policy accept this combination of SPF and DKIM?

The journey — 2 hopstotal 900s

  1. 1. from mail.sender.com to relay.example.net

    2026-08-11 09:00:30 UTC · ESMTP

  2. 2. from relay.example.net to mx.google.com

    2026-08-11 09:15:30 UTC · ESMTPS+900s

Headers

from
Billing <billing@sender.com>
to
you@gmail.com
subject
Invoice attached
date
Tue, 11 Aug 2026 09:00:00 +0000
reply-to
recovery@totally-different.com
message-id
<20260811090000.1234@sender.com>

How to Use the Email Header Analyzer Online

Email Header Analyzer: before and after TEXT A YOUR INPUT EMAIL HEADERANALYZER DONE A RESULT

Reads an email’s journey, finds the slow hop, and checks SPF, DKIM and DMARC. Headers are read bottom to top, oldest first, which is the opposite of how they appear — and the three authentication results together are what decide whether a message is trusted or filtered.

No software to install Free Works on any device

Step-by-Step Guide to Using the Email Header Analyzer

  1. 1. Paste the full email headers — the instructions for finding them are on this page

  2. 2. The answer appears as you type

    there is no button to press.

  3. 3. What it means is explained underneath, not just the number

Try it now

What is the Email Header Analyzer?

Reads an email’s journey, finds the slow hop, and checks SPF, DKIM and DMARC. Headers are read bottom to top, oldest first, which is the opposite of how they appear — and the three authentication results together are what decide whether a message is trusted or filtered.

Why Use Web Development Tools in the Browser?

Small web jobs like minifying CSS, checking HTML, escaping a string or writing a Dockerfile rarely deserve a new install. These tools do each one in a tab, and your code is never sent to a server.

“The fastest tool is the one already open in a tab.”
  • Code checked for errors
  • Messy code made readable
  • Number bases converted
  • Selectors and paths tested
  • Minified files for faster pages
  • Config files from templates
  • CI workflows drafted quickly
  • Source code stays private

Popular Uses for Developer Utilities

These are the small tasks that interrupt a day of web work.

  • Minifying assets Shrink CSS or JSON before deploying, then beautify it again to read.
  • Validating markup Catch unclosed tags and syntax errors in HTML, CSS or JavaScript before publishing.
  • Docker setups Draft a Dockerfile, Docker Compose file or .dockerignore for a new project.
  • CI pipelines Generate a GitHub Actions or GitLab CI workflow and adjust it to fit.
  • Number conversions Convert between binary, decimal, hex and octal while reading low-level data.
  • Selector testing Try a CSS selector or JSONPath expression against sample input and see matches.
  • Data URIs Turn a small image into a data URI to embed directly in CSS.
  • Project files Create .gitignore, EditorConfig and CODEOWNERS files without copying them from old repos.

What You Can Do with the Email Header Analyzer

Generates syntax the target program will accept, tested against its own grammar

Explains what each directive does, because a config file copied blind is a future outage

Why Use ToolXkit for Email Header Analyzer?

Your files stay with you

Everything runs inside your browser. Nothing you open or type is uploaded to a server.

Web Dev Tools for Different Users

Front-end developers

Validate, minify and beautify HTML, CSS and JavaScript as part of daily work.

DevOps engineers

Draft Docker, cron and CI files quickly, then refine them in the repo.

Coding students

Learn number systems, escapes and selectors by trying examples and seeing results.

Technical writers

Escape code samples and check snippets before putting them into documentation.

QA testers

Write clear bug reports and test CSS selectors against real page markup.

Open source maintainers

Set up issue templates, CODEOWNERS and gitattributes for a shared project on GitHub.

Best Times to Validate or Minify Code

Keep these open in a tab when you are:

  • Starting a new repository
  • Preparing a site for launch
  • Tracking down a syntax error
  • Containerising an app
  • Setting up automated builds
  • Reading hex or binary values
  • Writing a bug report
  • Working on a locked-down laptop

Frequently Asked Questions

Answers to common questions about this tool.

Do I need to install anything to use the Email Header Analyzer?

No. Email Header Analyzer runs entirely in your browser — there is nothing to download, no extension and no desktop program. It works the same on Windows, macOS, Linux, Android and iPhone.

Is it safe to use the Email Header Analyzer online?

Safer than the usual alternative, yes. Most online tools upload your file to a server you know nothing about, where it sits until someone deletes it. Here the file never leaves your device — the processing happens in the page itself, so there is no server copy to leak, retain or sell.

Is my code sent to a server when I use Email Header Analyzer?

No. Your code is processed in the browser tab, so private repositories, keys in config files and client work stay on your machine. It also means the tool works on locked-down work laptops where installing software is not allowed.

Will minifying break my code?

Minifying removes spaces, comments and line breaks without changing what the code does. Keep an unminified copy for editing, and test the minified version before deploying it.

Are the generated config files ready to use?

They give you a sound starting point based on common settings. Every project is different, so read through the file and adjust paths, versions and secrets before committing it.

Is Email Header Analyzer free with no account?

Yes. There is no login, API key or usage cap. Open the page whenever you need it, even on a machine that is not your own.

Does Email Header Analyzer follow current web standards?

The validators and generators follow current web standards and common tool conventions. Standards keep moving, so for edge cases check MDN or the official specification listed in further reading.

Further reading

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