email headers

Reading Email Headers

The five header lines that settle a deliverability question, and what a gap in the Received chain is telling you.

Analizador de encabezados de correoPruébelo en su propio dominio primero. Gratis, sin cuenta.

What does the header analyzer do?

Paste the raw headers of an email and the analyzer breaks down the full delivery path (every server hop), the SPF, DKIM and DMARC authentication results, and where time was lost between servers.

When to use it

Use it to debug why a message went to spam, to confirm your authentication is actually passing at the receiver, or to trace unexpected delays in delivery. It reads the same Received and Authentication-Results headers mailbox providers use.

How to get email headers

In Gmail open the message, click the three-dot menu and choose “Show original”. In Outlook open the message and use File then Properties. In Apple Mail use View, Message, Raw Source. Copy everything and paste it in.

The five header lines that matter

Authentication-Results carries the receiving server’s own SPF, DKIM and DMARC verdict, and it is the only opinion that counts. Received-SPF shows which domain was checked. DKIM-Signature names the signing domain and selector. Return-Path is the bounce address SPF is actually evaluated against. The Received chain shows the route and the timing.

Reading delays in the Received chain

Received headers stack newest first, so read them bottom to top. Each one carries a timestamp. A gap of minutes between two hops usually means greylisting or a queue at the receiving end, which is a very different problem from a message that arrived instantly and went to spam anyway.

Check yours now

Grab the raw source of a message that went wrong and paste it into the free email header analyzer. If the Authentication-Results line points at a DNS problem rather than a content one, the free email health check reads your published records back out of DNS.

How to read an email header

Extract raw headers from a message and work out why it was filtered or delayed.

Get the raw sourceIn Gmail use Show original. In Outlook use File then Properties. In Apple Mail use View, Message, Raw Source. Copy the whole block, including the Received lines.
Paste it into the analyzerThe tool parses the hops and the authentication results so you do not have to read the raw text.
Check Authentication-Results firstThis is the receiver's verdict on SPF, DKIM and DMARC. If DMARC failed here, nothing further down matters until you fix alignment.
Read the Received chain bottom to topThe oldest hop is at the bottom. Follow the route forward and note the timestamp on each hop.
Look for the gapA multi-minute jump between two hops points at greylisting or a receiver-side queue. No gap plus a spam verdict points at reputation or content instead.

Preguntas frecuentes

Is the header analyzer free?

Yes, analyzing email headers is free and requires no account.

What can email headers tell me?

They show every server the message passed through, the SPF/DKIM/DMARC results, timestamps and delays, and the originating IP. That is everything you need to diagnose a deliverability problem.

How do I find the raw headers?

In Gmail use "Show original"; in Outlook use File then Properties; in Apple Mail use View, Message, Raw Source.

Are my pasted headers stored?

Headers are analyzed to produce the result and are not used for anything else.

How do I read the Received chain?

Bottom to top. The last server to touch the message adds its Received line at the top, so the oldest hop is at the bottom. Compare the timestamps to find where the message waited.

What does Authentication-Results tell me?

It is the receiving server's own verdict: spf=pass or fail, dkim=pass or fail, and dmarc=pass or fail, each with the domain that was checked. If your own tests pass but this line fails, trust this line.

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