CheckForUpdatesCompleted Event

public event ExtendedAsyncCompletedEventHandler<TResult> CheckForUpdatesCompleted

Public Event CheckForUpdatesCompleted ExtendedAsyncCompletedEventHandler(Of TResult)

public:
 event ExtendedAsyncCompletedEventHandler<TResult>^ CheckForUpdatesCompleted

Shows how to handle Update event and use the CheckForUpdatesAsync asynchronous method to check for updates/notifications from the IMAP server (Task-based asynchronous approach).

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

...

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

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

    // Or you can specify the IMAP port with 
    // client.Connect("myserver", 143); 
 
    // Login to the server. 
    await client.AuthenticateAsync("user", "password");

    // ... 
 
    // Select the 'INBOX' mailbox. 
    await client.SelectAsync("INBOX");

    // Register an event handler. 
    client.Update += client_Update;

    while (true)
    {
        // Check for updates in 10 seconds. 
        await client.CheckForUpdatesAsync(10000);

        // Check your loop condition. 
        // ... 
    }

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

void client_Update(object sender, ImapUpdateEventArgs e)
{
    switch (e.Event)
    {
        case ImapUpdateEvent.MessageCount:
            Console.WriteLine("New message received.");
            // You can download the newly received message here. 
            break;

        case ImapUpdateEvent.MessageRemoved:
            Console.WriteLine("One or more messages removed.");
            break;
    }
}

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

...

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

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

    ' Or you can specify the IMAP port with 
    ' client.Connect("myserver", 143); 
 
    ' Login to the server. 
    Await client.AuthenticateAsync("user", "password")

    ' ... 
 
    ' Select the 'INBOX' mailbox. 
    Await client.SelectAsync("INBOX")

    ' Register an event handler. 
    AddHandler client.Update, AddressOf client_Update

    Do 
        ' Check for updates in 10 seconds. 
        Await client.CheckForUpdatesAsync(10000)

        ' Check your loop condition. 
        ' ... 
    Loop 
 
    ' ... 
 
    ' Disconnect. 
    client.Disconnect()
End Sub 
 
Private Sub client_Update(ByVal sender As Object, ByVal e As ImapUpdateEventArgs)
    Select Case e.Event 
        Case ImapUpdateEvent.MessageCount
            Console.WriteLine("New message received.")
            ' You can download the newly received message here. 
 
        Case ImapUpdateEvent.MessageRemoved
            Console.WriteLine("One or more messages removed.")
    End Select 
End Sub

Shows how to handle Update event and use the CheckForUpdatesAsync asynchronous method to check for updates/notifications from the IMAP server (Event-based asynchronous approach).

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

...

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

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

    // Or you can specify the IMAP port with 
    // client.Connect("myserver", 143); 
 
    // Login to the server. 
    client.Authenticate("user", "password");

    // ... 
 
    // Select the 'INBOX' mailbox. 
    client.Select("INBOX");

    // Register an event handler. 
    client.CheckForUpdatesCompleted += client_CheckForUpdatesCompletedCompleted;
    client.Update += client_Update;

    // Check for updates in 10 seconds. 
    client.CheckForUpdatesAsync(10000);

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

void client_Update(object sender, ImapUpdateEventArgs e)
{
    switch (e.Event)
    {
        case ImapUpdateEvent.MessageCount:
            Console.WriteLine("New message received.");
            // You can download the newly received message here. 
            break;

        case ImapUpdateEvent.MessageRemoved:
            Console.WriteLine("One or more messages removed.");
            break;
    }
}

void client_CheckForUpdatesCompletedCompleted(object sender, ExtendedAsyncCompletedEventArgs<bool> e)
{
    Imap client = (Imap)sender;
    if (e.Error != null)
        Console.WriteLine("Error: " + e.Error.ToString());
    else 
    {
        // Check for updates again. You might want to check some condition before going into the loop again. 
        client.CheckForUpdatesAsync(10000);
    }
}

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

...

Public Sub DoNoopAsync()
    ' Create a new instance of the Imap class. 
    Dim client As New Imap()

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

    ' Or you can specify the IMAP port with 
    ' client.Connect("myserver", 143); 
 
    ' Login to the server. 
    client.Authenticate("user", "password")

    ' ... 
 
    ' Select the 'INBOX' mailbox. 
    client.Select("INBOX")

    ' Register an event handler. 
    AddHandler client.CheckForUpdatesCompleted, AddressOf client_CheckForUpdatesCompletedCompleted
    AddHandler client.Update, AddressOf client_Update

    ' Check for updates in 10 seconds. 
    client.CheckForUpdatesAsync(10000)

    ' ... 
 
    ' Disconnect. 
    client.Disconnect()
End Sub 
 
Private Sub client_Update(ByVal sender As Object, ByVal e As ImapUpdateEventArgs)
    Select Case e.Event 
        Case ImapUpdateEvent.MessageCount
            Console.WriteLine("New message received.")
            ' You can download the newly received message here. 
 
        Case ImapUpdateEvent.MessageRemoved
            Console.WriteLine("One or more messages removed.")
    End Select 
End Sub 
 
Private Sub client_CheckForUpdatesCompletedCompleted(ByVal sender As Object, ByVal e As ExtendedAsyncCompletedEventArgs(Of Boolean))
    Dim client As Imap = CType(sender, Imap)
    If e.Error IsNot Nothing Then 
        Console.WriteLine("Error: " & e.Error.ToString())
    Else 
        ' Check for updates again. You might want to check some condition before going into the loop again. 
        client.CheckForUpdatesAsync(10000)
    End If 
End Sub

Reference