SELECT AccessingUser,MailboxAccessed,AccessRights
FROM OpenExchangePSQuery(
    POWERSHELL, '
Get-Mailbox | Get-MailboxPermission | where {$_.user.tostring() -ne "NT AUTHORITY\SELF" -and $_.IsInherited -eq $false} | Select @{Name="AccessingUser"; Expression={$_.user}}, @{Name="MailboxAccessed"; Expression={$_.identity}}, @{Name='AccessRights';Expression={[string]::join(', ', $_.AccessRights)}}



              ', POWERSHELL
)