DeliveryNotificationOptions won't work on gmail and hotmail
<p>I am using SmtpClient to send a message through a gmail account, I set DeliveryNotificationOptions to DeliveryNotificationOptions.OnSuccess, the message sent ok, but there is no delivery notifiacton. I also tried hotmail, still no delivery notification. However the same code works fine on outlook exchange server.</p>

<p>any ideas? Cheers
Harry</p>
