Display Full Access Permission on Exchange Mailbox
This command will show you who has full access to a mailbox - explicitly added permissions only - using the EMS. You could of course do it one by one in the EMC if you like pain.
Get-Mailbox -Server “mailboxserver” | Get-MailboxPermission | where { (\(\_.AccessRights -eq “FullAccess”) -and (\)_.IsInherited -eq \(false) -and -not (\)_.User -like “NT AUTHORITY\SELF”) } | fl