ComponentPro UltimateMail

      Cancelling an operation

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      To abort any transfer (downloading or uploading message) in progress you can either call the Cancel method or simply close the connection by calling the Disconnect or DisconnectAsync method.

      The following steps show how to use it.

      Cancelling an operation

      1. Add using directives to your code to create aliases for existing namespaces and avoid having to type the fully qualified type names. The code looks similar to the following:
        using System;
        using ComponentPro.Net.Mail;
        
      2. Create a new instance of the Smtp class.
      3. Now you can connect to the SMTP server with Connect methods. The code looks similar to the following:
        // Create a new Smtp instance.
        Smtp client = new Smtp();
        
        // Connect to the SMTP server.
        client.Connect("myserver");
        
      4. Use your user name and password to login with Authenticate methods. The code looks similar to the following:
        // Authenticate.
        client.Authenticate("test", "test");
        
      5. In this example, we will demonstrate how to abort a message download when the total bytes transferred exceeds 500Kb. It can be achieved by registering an event handler to the Progress event and call the Cancel method in this method. Other scenario is creating a Cancel button on your form and call the Cancel method when user clicks on it. The event handler of the Progress event looks similar to:
        void client_Progress(object sender, SmtpProgressEventArgs e)
        {
            // Abort the download operation if the bytes transferred is greater than or equal to 500Kb. 
            if (e.State == SmtpTransferState.Sending && e.BytesTransferred >= 1024 * 500)
            {
                ((Smtp)sender).Cancel();
            }
        }
        
      6. Now create a new mail message and send it. The code looks similar to the following:
        // Register an event handler.
        client.Progress += client_Progress;
        
      7. After completing your work, call the Disconnect method to close the SMTP session.

      Final example code

      using System;
      using ComponentPro.Net.Mail;
      
      ...
      
      public void DoAbort()
      {
          // Create a new Smtp instance. 
          Smtp client = new Smtp();
      
          // Connect to the SMTP server. 
          client.Connect("myserver");
      
          // Authenticate. 
          client.Authenticate("test", "test");
      
          try 
          {
              // Register an event handler. 
              client.Progress += client_Progress;
      
              // Load an existing mail message. 
              MailMessage msg = new MailMessage("c:\\temp\\my message.eml");
      
              // And send it. 
              client.Send(msg);
          }
          catch (SmtpException exc)
          {
              Console.WriteLine("Exception: " + exc.Message);
          }
      
          // Disconnect. 
          client.Disconnect();
      }
      
      void client_Progress(object sender, SmtpProgressEventArgs e)
      {
          // Abort the download operation if the bytes transferred is greater than or equal to 500Kb. 
          if (e.State == SmtpTransferState.Sending && e.BytesTransferred >= 1024 * 500)
          {
              ((Smtp)sender).Cancel();
          }
      }