We had a request recently to list what users have rights to a specific users mailbox.
This can easily be done using the following command.
Get-MailboxPermission –Identity “UserName” | fl user, accessrights
This gives an output like below.
If you would like to see permissions for every users mailbox run the following command
Get-MailboxPermission -Identity * | fl user, accessrights , identity > C:Perms.txt
(You can change the file location to wherever you would like)
The list of the Users and Permissions will all be in the Perms.txt file.