Outlook - Access another Person's Mailbox

You can access another person’s mailbox if you have been granted the appropriate permissions to their mailbox.

Consider these scenarios:

• A manager needs an assistant to monitor email on his or her behalf. In this scenario, an assistant that has been granted the appropriate permissions to a manager’s mailbox can view the manager’s mailbox.
• A manager needs an assistant to monitor a specific folder on his or her mailbox. In this scenario, an assistant that has been granted the appropriate permissions to a folder in a manager’s mailbox can view only the contents of that particular folder of the manager’s mailbox.

Click on this link to read more: Access another person's mailbox - Microsoft Support