A technical email header is the top section of an email that contains important information about the message, such as the sender’s name and email address, the date and time the email was sent, and the subject line. It also includes technical details, such as the email’s unique identifier, known as the Message-ID, and the email’s route through various servers, known as the Received headers. These technical details are crucial for troubleshooting and tracking the delivery of an email, making the technical email header an essential component of any email communication.