Definitions for "Email header"
Keywords:  sender, bcc, route, message, recipient
a section of an email message that is used by a mail server to route and deliver an email message
a section of an email message, which is usually hidden by most email programs, that contains detailed information about the origination of the message
Information that identifies the sender and recipient of a message, information about how the message was routed through the network, the date and time at which the message was sent, and the subject of the message.