How to Check Email Headers: SPF, DKIM and DMARC

By Ahsan

Email headers are the metadata block carried at the top of every email message. The block records the route a message took between mail servers, the authentication checks applied to it, and the software that handled it along the way. A message that reaches an inbox with a forged sender address still carries the headers added by each server on its route, and those headers form the record used to establish where the message came from and whether it was altered in transit.

Message structure

A message consists of a header block and a body, separated by a blank line. The header block holds named fields such as From, To, Subject, Date and Message-ID, together with MIME fields that describe how the body is encoded. The sending client writes the first fields, and each server on the route adds further fields.…