Email header analyzer

Yes. It parses your headers entirely in your browser — nothing is uploaded or stored. Paste the raw headers, read the analysis, and close the tab; nothing leaves your machine.

In Gmail, open the message, click the three-dot menu and choose "Show original". In Outlook, open the message and use File → Properties (or "View message source"). In Apple Mail, View → Message → All Headers (or Raw Source). Copy everything from the top down to the first blank line and paste it here.

It reads the authentication results (SPF, DKIM, DMARC), the key fields (From, To, Subject, Date, Message-ID, Return-Path), and the full Received chain — every server hop the message passed through, in order, with the delay at each step and the total delivery time.

Long gaps between hops can indicate greylisting, throttling, or a slow relay — all of which correlate with reputation problems. Combined with failed SPF/DKIM/DMARC, the Received chain often pinpoints exactly where a message went wrong on its way to the inbox.