How to make a mailbox read all mail from all other mailboxes?

Question

Mail server

There is mail on the domain of our organization. There are mailboxes for various departments (secretary, legal department, accounting, director, etc.).
It is necessary to make sure that the secretary's mailbox receives mail from all other mailboxes, while when the secretary views these messages, they are marked as read only from him (the secretary), and for all other employees they remain new (unread). In addition, if any employee sends a letter or answers an incoming one, then the secretary must also see all this (ie, see all sent letters and all replies in the email threads).
How to organize this?

Answer 1

In the settings:
and there mark "copy letters along with folders."