The OnDelivered event is generated after a message has been
successfully submitted to the mail server for delivery. When used in
conjunction with the OnRecipient and OnProgress events,
this event can be used to track the delivery of a message to multiple
recipients. If the message was not delivered, either because delivery
was canceled in the OnRecipient event or because of an error,
the OnDelivered event will not fire.
The Address argument is a string which specifies the
recipient email address.
The MessageSize argument is a long integer which specifies
the size of the message that was delivered.
Note that even though a message has been successfully delivered to
the mail server, it may not actually be delivered to the recipient.
The server may accept the message and then subsequently decide to
reject or re-route the message based on its own internal
configuration. To confirm message delivery to the actual user, use
the delivery status notification options and/or set the
ReturnReceipt property to an address which will be notified
when the message has been read.