> 
> Get-Mailbox | Get-MailboxPermission -user 
> 
> 
> Get-Mailbox | Get-MailboxPermission -user | Where {$\_.AccessRights -like "*send*as\*"}
> 
> 
> Get-Mailbox | Get-ADPermission | Where {$\_.extendedRights -like "*send-as*"}
> 
> 
> 

All of the above commands does not work for me