Lend me your ears.
You do not have a right to privacy (for the most part) on your work computer. And your employer is getting advice like this from employment lawyers, telling them to read your emails:
Delaware Employment Lawyers recommend employees “monitor” employee emails.
“And, by “monitor,” I actually mean monitor—not threaten to monitor. Having an effective e-mail monitoring system in place and following it can sometimes help to prevent situations such as this while employees are still working.”
What else do they advise their clients?
“Employers should have a procedure in place whereby, immediately upon the termination of any employee or upon receipt of notice from an employee that he or she intends to quit, the employer: (1) has its IT department (or consulting firm) preserve the employee’s email account; and (2) has management or HR personnel review the emails for critical information such as evidence of a leak of confidential information.”
Get that? They are telling clients to read your emails. The ones sent from your work email – and maybe, just maybe, other things you have created or sent from work email.
So if you are going to leave, compete, start a business or frankly just don’t like working there, keep your opinion out of email. Please. Keep it out.