Are headers uploaded?

No. This analyzer runs in your browser and does not call the DNS API.

Where do I find raw headers?

Most email clients call this Show original, View source, View message details, or Download original.

They show authentication outcomes for one message, but ongoing deliverability needs monitoring across campaigns.

HDR tool

Analyze raw headers locally in the browser. The text is not sent to the server.

SenderDNSReceiver

HDR

Enter a domain to run the check.

The parser looks for Authentication-Results, Received-SPF, DKIM signatures, DMARC outcomes, sender domains, and the number of Received hops.

Header analysis runs in the browser only. Do not paste confidential messages into any online tool unless your policy allows it.