How to Get Raw Email Headers
Gmail
Open the email → click the three-dot menu (⋮) in the top right → Show original. Copy everything from the top of the page down to the blank line before the email body.
Outlook / Office 365
Open the email → click File → Properties. The headers are in the "Internet headers" box at the bottom. Or in Outlook on the web: open the message → three-dot menu → View → View message source.
Apple Mail
Open the email → go to View → Message → All Headers (or press Shift+Cmd+H). Select all and copy.
What Are SPF, DKIM, and DMARC?
SPF (Sender Policy Framework) — checks whether the sending mail server's IP is authorised to send on behalf of the domain in the From address. A fail suggests possible spoofing.
DKIM (DomainKeys Identified Mail) — a cryptographic signature verifying the email hasn't been tampered with in transit and was sent by an authorised server for that domain.
DMARC (Domain-based Message Authentication) — ties SPF and DKIM together. It tells receiving mail servers what to do if either check fails — reject, quarantine, or do nothing.