Abstract: Methods, systems, and data structures are provided for assigning categories to electronic mail (email). An email includes a category identification field, a sender category identification field, and a receiver category identification field. When the email is transmitted any sender assigned category identification being made by the sender is placed in the sender category identification field, and any previous value contained in the sender category identification field is moved to the category identification field and the receiver category identification field. In some embodiments, the sender category identification field and the receiver category identification field can include distribution lists associated with multiple senders and multiple receivers of the email. When the email is received any value included in the category identification field is presented with the email.