Setting up Exchange 2013?

Question

Microsoft Exchange

Good day, please tell me how to set up Exchange 2013 access levels. There is the following task: Set up viewing of all letters, by hierarchy (for example: each employee has his own mailbox, the employee himself has access to this mailbox, his boss, deputy director and director, and the rest of the employees cannot see the letters of this mailbox). I myself see a solution to the problem as follows: create a separate database (public) for each box and then give access to it to certain users. My solution is more expensive, so I ask for help in solving this problem. Thank you.