The Mailing_OnMailStatus event occurs when a message is being moved from the Outbox folder to either the Sent or Aborted folder. The Mailing_OnMailStatus event is a good time for you to place some code to update the receiver database. The intrinsic Mail Object will reflect the aborted or sent message.
Sub Mailing_OnMailStatus(Status)
. . .
End Sub
Sub Mailing_OnMailStatus(Status)
    If Status = 13 Then
        DisableContactEMail(Mail.Headers("X-Contact-ID"))
    End If
End Sub
The Mail
Object  is only initialized with the mail header; the Contents
collection  is empty. 
The DataSource object is not
available at this point. Direct Database access should be used.