“My coworker was recently fired for sending email messages with sexually explicit content to women in the office. He was terminated but now the company says that it’s going to monitor all of our email messages that are sent on our company email system to make sure that we don’t violate the company’s policy against harassment. Can they do this?”
The short answer is: usually yes. It may seem unfair and feel like your employer is invading your privacy when they reads your email messages, but the reality is that many employers monitor email and Internet use, and courts have almost uniformly upheld their right to do so.
However, if a company assures workers that their email messages will remain private and takes steps to protect the privacy of email (by providing a system that allows messages to be designated “confidential” or creating private passwords known only to the employee, for example), a worker might have a legitimate gripe about company monitoring. These assurances will usually be in an Employee Handbook or Employment Contract.
It sounds like your employer has been upfront about its plans to read email and hasn’t given you any reason to believe that your messages are private. Practically they have an interest in preventing sexual harrassment such as may have occurred with your former colleague. Therefore, you shouldn’t put anything in an email on the company system that you wouldn’t want your boss to read.