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ComponentPro UltimateMail

Downloading mail message Asynchronously

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Use DownloadMailMessageAsync methods to asynchronously download a message from the server. These methods download a message from the server asynchronously with execution occurring on a new thread, therefore they allow your next line of code to execute immediately.

In Task-based Asynchronous programs, the single asynchronous method represents the initiation and completion of an asynchronous operation. You may create the continuation code either explicitly, through methods on the Task class (for example, ContinueWith) or implicitly, by using language support built on top of continuations (for example, await in C#, Await in Visual Basic).

In .NET 4.5 it is recommended to implement the Task-based Asynchronous Pattern.

In Event-based Asynchronous programs, the event DownloadMailMessageCompleted is raised when the DownloadMailMessageAsync method completes. In the event handler method of the DownloadMailMessageCompleted, you can check if there were any errors by using the Error property of the event data object.

The following example demonstrates how to asynchronously download a message from the server:

Task-based approach

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

...

// Create a new instance of the Pop3 class.
Pop3 client = new Pop3();

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

// Or you can specify the POP3 port with 
// client.Connect("myserver", 110); 
 
// Login to the server.
client.Authenticate("user", "password");

// ... 
 
// Download a mail message with sequence number 1.
MailMessage msg = await client.DownloadMailMessageAsync(1);

// ...
Console.WriteLine("Message downloaded successfully.");
Console.WriteLine("Message ID: {0}, Subject: {1}", msg.MessageIdentifier, msg.Subject);

// Disconnect.
client.Disconnect();

Event-based approach

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

...

public void DoDownloadMailMessageAsync()
{
    // Create a new instance of the Pop3 class. 
    Pop3 client = new Pop3();

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

    // Or you can specify the POP3 port with 
    // client.Connect("myserver", 110); 
 
    // Login to the server. 
    client.Authenticate("user", "password");

    // ... 
 
    // Register an event handler. 
    client.DownloadMailMessageCompleted += client_DownloadMailMessageCompleted;

    // Download a mail message with sequence number 1. 
    client.DownloadMailMessageAsync(1);

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

void client_DownloadMailMessageCompleted(object sender, ExtendedAsyncCompletedEventArgs<MailMessage> e)
{
    // Pop3 client = (Pop3)sender; 
    if (e.Error != null)
        Console.WriteLine("Error: " + e.Error.ToString());
    else 
    {
        MailMessage msg = e.Result;

        Console.WriteLine("Message downloaded successfully.");
        Console.WriteLine("Message ID: {0}, Subject: {1}", msg.MessageIdentifier, msg.Subject);
    }
}