Email header check

Paste an email’s headers to review its authentication results, sending servers and spam-filter details.

The email’s headers, or the whole raw message

Up to 256 KB

Copy them from the message in the inbox or junk folder that received it, not from your Sent folder. We read the headers only: anything after the first blank line is the message itself and is dropped before we look. The saved report keeps the sender details and server names it shows, the recipient as a domain only (someone@icloud.com), and never the text you pasted.

Where to find the headers

Gmail: open the message, click the three dots next to Reply, then “Show original”. Copy the page or use “Copy to clipboard”.
Apple Mail: select the message, then View › Message › Raw Source. Select all and copy.
Outlook: open the message, click the three dots, then View › View message source (web) or File › Properties and copy “Internet headers” (desktop).
iCloud.com: open the message, click the Reply arrow menu, then “Show All Headers”.
Yahoo Mail: open the message, click the three dots, then “View raw message”.

What we check

Did it pass authentication?

The receiving server records whether SPF, DKIM and DMARC passed. We read that verdict and whether the signature matches your From address.

Who sent it

The From address, where replies and bounces go, the server that sent it and the domain that signed it, with anything that looks off flagged.

What the spam filter said

iCloud, Outlook, SpamAssassin and others leave marks and scores in the headers. We show each one and what it means.

The journey

Every server the message passed through, with timestamps, the wait at each step and basics like Message-ID, Date and unsubscribe headers.

What this check can’t tell you

Why the filter decided what it did

Headers record the result, not the reasoning. When authentication passes and the message still lands in spam, the cause is usually the sender’s reputation, which no header spells out.

Anything about the message itself

We drop everything after the headers without reading it, so the wording, links and images aren’t judged.

Whether your DNS records are right today

The headers show what the receiver saw at the time. For the current state of your SPF, DKIM and DMARC records, run the email deliverability check.

Headers from your Sent folder

A message in Sent hasn’t been through a receiver yet, so it carries no verdicts. Copy the headers from the mailbox that received it.