Update Event

public event EventHandler<TEventArgs> Update

Public Event Update EventHandler(Of TEventArgs)

public:
 event EventHandler<TEventArgs>^ Update

Show how to handle the Update event.

using System;
using ComponentPro.Net.Mail;

...

public void HandleUpdateEvent()
{
    // Create a new instance. 
    Imap client = new Imap();

    client.Update += client_Update;

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

    // Authenticate. 
    client.Authenticate("test", "test");

    // ... 
 
    while (!quit)
    {
        // Check for updates every 1 min. 
        client.CheckForUpdates();

        System.Threading.Thread.Sleep(60 * 1000); // Sleep 1 min. 
 
        // ... 
    }

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

void client_Update(object sender, ImapUpdateEventArgs e)
{
    Console.WriteLine("New event: " + e.Event);
}

Imports ComponentPro.Net.Mail

...

Public Sub HandleUpdateEvent()
    ' Create a new instance. 
    Dim client As New Imap()

    AddHandler client.Update, AddressOf client_Update

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

    ' Authenticate. 
    client.Authenticate("test", "test")

    ' ... 
 
    Do While Not quit
        ' Check for updates every 1 min. 
        client.CheckForUpdates()

        System.Threading.Thread.Sleep(60 * 1000) ' Sleep 1 min. 
 
        ' ... 
    Loop 
 
    ' ... 
 
    ' Disconnect. 
    client.Disconnect()
End Sub 
 
Private Sub client_Update(ByVal sender As Object, ByVal e As ImapUpdateEventArgs)
    Console.WriteLine("New event: " & e.Event)
End Sub

Shows how to handle Update event and use the Noop method to check for updates from the IMAP server.

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

...

static void Main()
{
    // IMAP server information. 
    const string serverName = "imap.gmail.com";
    const string user = "username@gmail.com";
    const string password = "password";
    const int port = 993;
    const SslSecurityMode securityMode = SslSecurityMode.Implicit;

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

    // Connect to the server. 
    client.Connect(serverName, port, securityMode);

    // Login to the server. 
    client.Authenticate(user, password);

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

    client.Update += client_Update;

    // ... 
 
    while (!quit)
    {
        // ... 
 
        // Wait for 10 seconds. 
        client.CheckForUpdates(10000);

        // ... 
    }

    // ... 
 
    // Close the connection. 
    client.Disconnect();
}

static 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 ComponentPro.Net
Imports ComponentPro.Net.Mail

...

Shared Sub Main()
    ' IMAP server information. 
    Const serverName As String = "imap.gmail.com" 
    Const user As String = "username@gmail.com" 
    Const password As String = "password" 
    Const port As Integer = 993
    Const securityMode As SslSecurityMode = SslSecurityMode.Implicit

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

    ' Connect to the server. 
    client.Connect(serverName, port, securityMode)

    ' Login to the server. 
    client.Authenticate(user, password)

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

    AddHandler client.Update, AddressOf client_Update

    ' ... 
 
    Do While Not quit
        ' ... 
 
        ' Wait for 10 seconds. 
        client.CheckForUpdates(10000)

        ' ... 
    Loop 
 
    ' ... 
 
    ' Close the connection. 
    client.Disconnect()
End Sub 
 
Private Shared 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

Reference