That part of a message that contains control information about the message such as the message creator and message type, the total length of the message, the time it was submitted, addressing information, and so forth.
The information at the beginning of an email or bulletin board message. Message headers contain the identities of the author and recipients, the subject of the message, and the date the message was sent.
Information at the top of an e-mail which says who sent it, where it came from, what path it took together with time-stamping information. This information can be used to track the message as it was sent from computer to computer across the Internet and identify the senders of bulk unsolicited email, known as spam.