Applicable to Office 365 with Administrator privileges to manage corporate emails. Here's an example on how to use Office 365 Mail Flow rules: The business owner (normally your company CEO or President) requested to monitor one or more of your employees mailboxes. Basically, he/she would like to know the incoming and outgoing messages without the employees knowing about it. Disclaimer: Before you apply this mail flow rule within your organization. You need to have an official permission request from the Authorized Users e.g. Business Owner, President or any Authorized Personnel. You need to create two new mail flow rules, for sender and recipients. In Exchange Admin Center , click the Mail Flow , then click on (+) to create a new rule. Create a New Rule . Fill up the following entry fields. Name: for example " Monitor - Sender " to monitor email sender. Apply this rule if, select " The Sender is ... " this will pop-up your organization email list.