Email headers

Path taken, delays, authentication results. Analysed in your browser.

Nothing you paste leaves your browser.

The analysis happens entirely in the page. Message headers contain the sender's address, the recipients', the IP addresses traversed and often the subject: there is no reason for them to reach a third-party server. This is the only tool on the site that requires JavaScript, and that is exactly why.

In Gmail: Show original. In Thunderbird: Ctrl+U. In Outlook: File > Properties > Internet headers.