The HTTP From request header includes an email address for the user in control of the client device that sent the HTTP request.
The From request header specifies the email address of the user, and hence can be used to contact them if there is a problem with the HTTP request. If an automated agent such as a web crawler is in use, the From header must be included. This will allow server administrators to contact the controller in case the robot is misbehaving.
The From header is NOT intended to be used for authentication.
The HTTP From request header is used to contact the human that is responsible for sending the HTTP request.