The capability of an employee to violate the policy of an organization is a concern for an employer. Monitoring is a measure taken by an employer to discourage an employee from acting inappropriately. However, current monitoring techniques tend to raise privacy issues because they violate the privacy rights of employees. Applying a monitoring technique without violating the privacy of employees is the aim of this paper. We propose a design and a protocol which give an employer the opportunity to monitor employee email in order to detect company policy violations. This can be achieved without violating the privacy of honest employees, while at the same time revealing evidence about the illegal actions of dishonest employees.