An email sending service embeds identifying information within emails sent
on behalf of its service consumers. A recipient notifies their email
provider that an email received from the service is a spam email (e.g.,
an unsolicited message). The email provider forwards a complaint,
including a copy of the email, to the email sending service. The service
utilizes the information embedded in the email to identify the
responsible service consumer. The email sending service then takes
corrective action as necessary to prevent or deter the identified service
consumer from sending subsequent spam emails.