Get-Mailbox

From Get-Mailbox - MS Technet page

Use the Get-Mailbox cmdlet to view mailbox objects and attributes, to populate property pages, or to supply mailbox information to other tasks

The Get-Mailbox cmdlet retrieves the attributes and objects for a mailbox. No parameters are required. If the cmdlet is used without a parameter, all mailboxes in the organization are listed.

To run the Get-Mailbox cmdlet, the account you use must be delegated the following:

• Exchange View-Only Administrator role