Do you remember that emails aren't your property?

The Australian Government Privacy Act permits employers to monitor employees' email (and web browsing) logs. While employers are encouraged to develop and promulgate a clear privacy policy, it's essentially a recommendation. Many employers may not have the resources to develop such a policy, but nothing prevents them from reviewing email records on the server. The Government admits that "system administrators are usually able to access everything on the network."

The sensible response for employees is to be careful about what they say in email and abide by appropriate usage rules / etiquette even if they don't exist! Follow common sense on this one. Remember that your work email address should not be used for personal mail.