KeepAliveCompleted Event

public event AsyncCompletedEventHandler KeepAliveCompleted

Public Event KeepAliveCompleted AsyncCompletedEventHandler

public:
 event AsyncCompletedEventHandler^ KeepAliveCompleted

Shows how to send a message using the KeepAliveAsync asynchronous method.

using System;
using System.ComponentModel;
using ComponentPro;
using ComponentPro.Net.Mail;

...

public async void DoSendAsync()
{
    // Create a new instance of the Smtp class. 
    Smtp client = new Smtp();

    // Connect to the server. 
    client.Connect("myserver");

    // Or you can specify the SMTP port with 
    // client.Connect("myserver", 25); 
 
    // Login to the server. 
    client.Authenticate("user", "password");

    // ... 
 
    MailMessage msg;

    // Create a new mail message. 
    msg = new MailMessage();
    msg.Subject = "Test Subject";
    msg.BodyText = "Content";
    msg.From = "from@mydomain.com";
    msg.To = "to@somedomain.com";

    // Send the message. 
    await client.SendAsync(msg);            

    Console.WriteLine("Message sent successfully.");
    // ... 
 
    // Disconnect. 
    client.Disconnect();

Imports System.ComponentModel
Imports ComponentPro
Imports ComponentPro.Net.Mail

...

Public Async Sub DoSendAsync()
    ' Create a new instance of the Smtp class. 
    Dim client As New Smtp()

    ' Connect to the server. 
    client.Connect("myserver")

    ' Or you can specify the SMTP port with 
    ' client.Connect("myserver", 25); 
 
    ' Login to the server. 
    client.Authenticate("user", "password")

    ' ... 
 
    Dim msg As MailMessage

    ' Create a new mail message. 
    msg = New MailMessage()
    msg.Subject = "Test Subject" 
    msg.BodyText = "Content" 
    msg.From = "from@mydomain.com" 
    msg.To = "to@somedomain.com" 
 
    ' Send the message. 
    Await client.SendAsync(msg)

    Console.WriteLine("Message sent successfully.")
    ' ... 
 
    ' Disconnect. 
    client.Disconnect()

Shows how to send a message using the KeepAliveAsync asynchronous method.

using System;
using System.ComponentModel;
using ComponentPro;
using ComponentPro.Net.Mail;

...

private MailMessage msg;
public void DoSendAsync()
{
    // Create a new instance of the Smtp class. 
    Smtp client = new Smtp();

    // Connect to the server. 
    client.Connect("myserver");

    // Or you can specify the SMTP port with 
    // client.Connect("myserver", 25); 
 
    // Login to the server. 
    client.Authenticate("user", "password");

    // ... 
 
    // Register an event handler. 
    client.SendCompleted += client_SendCompleted;
    client.KeepAliveCompleted += client_KeepAliveCompleted;

    // Create a new mail message. 
    msg = new MailMessage();
    msg.Subject = "Test Subject";
    msg.BodyText = "Content";
    msg.From = "from@mydomain.com";
    msg.To = "to@somedomain.com";

    // Send the message. 
    client.SendAsync(msg);

    // ... 
 
    // Disconnect. 
    client.Disconnect();
}

void client_KeepAliveCompleted(object sender, AsyncCompletedEventArgs e)
{
    Smtp client = (Smtp)sender;
    if (e.Error != null)
        Console.WriteLine("Error: " + e.Error.ToString());
    else 
    {
        if (!_quit)
        {
            // Sleep for 5 secs. 
            System.Threading.Thread.Sleep(5000);

            // Send another message. 
            client.SendAsync(msg);
        }
    }
}

void client_SendCompleted(object sender, AsyncCompletedEventArgs e)
{
    Smtp client = (Smtp)sender;
    if (e.Error != null)
        Console.WriteLine("Error: " + e.Error.ToString());
    else 
    {
        Console.WriteLine("Message sent successfully.");

        // Try to keep the connection alive. 
        client.KeepAliveAsync();
    }
}

Imports System.ComponentModel
Imports ComponentPro
Imports ComponentPro.Net.Mail

...

Private msg As MailMessage
Public Sub DoSendAsync()
    ' Create a new instance of the Smtp class. 
    Dim client As New Smtp()

    ' Connect to the server. 
    client.Connect("myserver")

    ' Or you can specify the SMTP port with 
    ' client.Connect("myserver", 25); 
 
    ' Login to the server. 
    client.Authenticate("user", "password")

    ' ... 
 
    ' Register an event handler. 
    AddHandler client.SendCompleted, AddressOf client_SendCompleted
    AddHandler client.KeepAliveCompleted, AddressOf client_KeepAliveCompleted

    ' Create a new mail message. 
    msg = New MailMessage()
    msg.Subject = "Test Subject" 
    msg.BodyText = "Content" 
    msg.From = "from@mydomain.com" 
    msg.To = "to@somedomain.com" 
 
    ' Send the message. 
    client.SendAsync(msg)

    ' ... 
 
    ' Disconnect. 
    client.Disconnect()
End Sub 
 
Private Sub client_KeepAliveCompleted(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs)
    Dim client As Smtp = CType(sender, Smtp)
    If e.Error IsNot Nothing Then 
        Console.WriteLine("Error: " & e.Error.ToString())
    Else 
        If Not _quit Then 
            ' Sleep for 5 secs. 
            System.Threading.Thread.Sleep(5000)

            ' Send another message. 
            client.SendAsync(msg)
        End If 
    End If 
End Sub 
 
Private Sub client_SendCompleted(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs)
    Dim client As Smtp = CType(sender, Smtp)
    If e.Error IsNot Nothing Then 
        Console.WriteLine("Error: " & e.Error.ToString())
    Else 
        Console.WriteLine("Message sent successfully.")

        ' Try to keep the connection alive. 
        client.KeepAliveAsync()
    End If 
End Sub

Reference