From

The From request header contains an Internet email address for a human user who controls the requesting user agent.

If you are running a robotic user agent (e.g. a crawler), the From header must be sent, so you can be contacted if problems occur on servers, such as if the robot is sending excessive, unwanted, or invalid requests.

Header type	Request header
Forbidden header name	no

From: <email>

From: webmaster@example.org