What Is an Email Header Analyzer?
Every email carries a hidden block of headers above the message. They record who sent it, every server it passed through, the time at each step, and whether the receiving mailbox trusted it. Reading them by hand is slow, because the lines are long, out of order and full of codes.
This email header analyzer turns that block into a clear report. You see the SPF, DKIM and DMARC results, whether they line up with the From address, the full delivery path with the delay at each hop, and warning signs such as a reply address on another domain. Use it when your own campaign lands in spam, when a customer says your email never arrived, or when a message looks like phishing.
Many header tools send what you paste to their server. Headers contain names, addresses and internal server details, so this one reads them only in your browser.
How to Analyze Email Headers
- Copy the full headers. Use the steps in the table below. Copy everything, not only the From and Subject lines.
- Paste them in the box. The report updates as you paste. The sample shows a well set up marketing email.
- Read the verdict and checks. Problems are shown first in plain words, with what to fix.
- Look at the delivery path. The slowest hop is highlighted, so you know which server held the email.
- Copy the report to share it with your developer or email service support team.
How to Find Email Headers
| Email app | Steps |
|---|---|
| Gmail | Open the email, click More next to Reply, then Show original. Click Copy to clipboard. |
| Outlook | Open the email, click File, then Properties. Copy the Internet headers box. |
| Apple Mail | Open the email, then View, Message, All Headers. |
| Yahoo Mail | Open the email, click More, then View Raw Message. |
These steps come from Google's guide to tracing an email with its full header.
What the Results Mean
| Check | What it tells you |
|---|---|
| SPF | Whether the sending server is listed in the SPF record of the bounce domain in Return-Path. |
| DKIM | Whether the message carries a valid signature, and which domain signed it with the d= tag. |
| DMARC | Whether SPF or DKIM passed for a domain that matches the visible From address. This is the result Gmail and Yahoo care about most. |
| Alignment | Whether the SPF or DKIM domain shares the same main domain as From, such as mail.yourshop.in and yourshop.in. |
| Delivery path | Each Received line, read from the bottom up, oldest first. Each server adds its line at the top. |
| One click unsubscribe | Whether List-Unsubscribe and List-Unsubscribe-Post are present for marketing mail. |
The Google email sender guidelines ask every sender to use TLS, and senders of more than 5,000 messages a day to Gmail to pass DMARC with an aligned From domain and to support one click unsubscribe.
Practical Tips
- Test your own campaigns. Send one to a Gmail and an Outlook address you own, then paste both headers here before you send to the full list.
- Read the top result. Forwarded mail can carry several authentication results. The top one was added by the final inbox, so that is the one the analyzer uses.
- DMARC fail with SPF pass? Your email service is using its own bounce domain. Set up DKIM for your domain in the service so DMARC can pass.
- Long delay at one hop? Look at the server named in the By column. Delays inside your own systems point to a queue; delays at the receiver often mean greylisting or spam scanning.
- Suspicious email? A DMARC fail, a reply address on another domain, or a display name showing a different address are all reasons not to click anything.
Fix What the Headers Show
Most problems trace back to DNS. Build a correct record with the SPF record generator and checker and the DMARC record generator. Then plan better campaigns with our email marketing strategy guide, and if your site sends mail itself, see send email code in PHP and contact form spam protection.
Frequently Asked Questions
1Is it safe to paste email headers here?
Yes. The analyzer runs entirely in your browser with JavaScript. Headers are never uploaded or stored, which matters because they contain names, email addresses and internal server details.
2Why does my email pass SPF but fail DMARC?
DMARC needs SPF or DKIM to pass for a domain that matches your From address. Email services often send with their own bounce domain, so SPF passes for their domain, not yours. Set up DKIM for your own domain in the service, or a custom bounce domain, and DMARC will pass.
3Which Received line is the first hop?
The bottom one. Every server adds its Received line to the top of the headers, so the oldest hop is at the bottom and the final inbox is at the top. The analyzer reverses them and shows the oldest hop first, with the delay between each step.
4Can headers prove who really sent an email?
They show which servers handled it and whether the sending domain authenticated it. A DMARC pass means the From domain approved the message. Lines added before the first trusted server can be faked, so trust the results added by your own inbox, at the top.