private static void SendMailFromCompleted(IAsyncResult result)
 {
     if (!result.CompletedSynchronously)
     {
         SendMailAsyncResult asyncState = (SendMailAsyncResult)result.AsyncState;
         try
         {
             MailCommand.EndSend(result);
             asyncState.SendTo();
         }
         catch (Exception exception)
         {
             asyncState.InvokeCallback(exception);
         }
     }
 }