In November 1999, New York Times fired 23 employees who were accused of contributing to a hostile work environment because they repeatedly traded personal e-mail messages that contain dirty jokes and nude pictures. In October 2000, Xerox fired 40 people for violating company's computer policies. Boeing has fired few on similar grounds too. There are several arguments an employer can make. Firstly, an employee is at work to do work.
Employers have a legitimate interest in a worker's performance.
Monitoring their e-mails is a tool to measure productivity. Secondly, employers can argue that their clients experience delays receiving and sending e-mails because the bandwidth is continuously consumed by entertainment oriented material. On the other side, and according to privacy advocates, employees have some arguments related to privacy. The main argument they make is that companies should not be monitoring their employees unless there is proof that they are failing to complete their work or misusing company's resources. To do so is in violation to their right of privacy.