[ObsoleteAttribute("This method is obsolete in .NET 4.5+. Use DownloadFoldersAsync instead.")]
public IAsyncResult BeginDownloadFolders(
	bool subscribedOnly,
	string parentFolderName,
	string pattern,
	AsyncCallback callback,
	Object state
)

<ObsoleteAttribute("This method is obsolete in .NET 4.5+. Use DownloadFoldersAsync instead.")>
Public Function BeginDownloadFolders ( 
	subscribedOnly As Boolean,
	parentFolderName As String,
	pattern As String,
	callback As AsyncCallback,
	state As Object
) As IAsyncResult

using System;
using MailBee;
using MailBee.ImapMail;

class Sample
{
    static void Main(string[] args)
    {
        Imap imp = new Imap();

        imp.Connect("mail.somehost.com");

        imp.Login("jdoe", "secret");

        // Initiate an asynchronous download folder list attempt.
        // This will download a single empty Folder element having only delimiter
        // field set. We need it in order to correctly combine pattern value for
        // subsequent folder list download.
        IAsyncResult ar = imp.BeginDownloadFolders(false, "", "", null, null);

        // Simulate some lengthy work here. At the same time,
        // folders are being downloaded is executed on another thread.
        System.Threading.Thread.Sleep(3000);

        // If the download is still in progress, then wait until it's finished,
        // and get the delimiter.
        FolderCollection folders = imp.EndDownloadFolders();

        if (folders.Count == 0)
        {
            Console.WriteLine("Bad IMAP4 server.");
        }
        else
        {
            string delim = folders[0].Delimiter;

            if (delim == null)
            {
                Console.WriteLine("Folder names are flat. Hierarchy is not supported.");
            }
            else
            {

                // Initiate an asynchronous download folder list attempt.
                // Here, we request to download all 1st level subfolders of the account.
                ar = imp.BeginDownloadFolders(false, "", "%" + delim + "%", null, null);

                // Simulate some lengthy work here. At the same time,
                // folders are being downloaded is executed on another thread.
                System.Threading.Thread.Sleep(3000);

                // If the download is still in progress, then wait until it's finished,
                // and get the folders.
                folders = imp.EndDownloadFolders();

                // Print folder names matching the specified criteria.
                foreach (Folder fold in folders)
                {
                    Console.WriteLine(fold.Name);
                }
            }
        }

        // Disconnect from the server.
        imp.Disconnect();
    }
}

Imports System
Imports MailBee
Imports MailBee.ImapMail

Module Sample
    Sub Main()
        Dim imp As New Imap

        imp.Connect("imap4.company.com")

        imp.Login("jdoe@company.com", "secret")

        ' Initiate an asynchronous download folder list attempt.
        ' This will download a single empty Folder element having only delimiter
        ' field set. We need it in order to correctly combine pattern value for
        ' subsequent folder list download.
        Dim ar As IAsyncResult = imp.BeginDownloadFolders(False, "", "", Nothing, Nothing)

        ' Simulate some lengthy work here. At the same time,
        ' folders are being downloaded is executed on another thread.
        System.Threading.Thread.Sleep(3000)

        ' If the download is still in progress, then wait until it's finished,
        ' and get the delimiter.
        Dim folders As FolderCollection = imp.EndDownloadFolders()

        If folders.Count = 0 Then
            Console.WriteLine("Bad IMAP4 server.")
        Else
            Dim delim As String = folders(0).Delimiter

            If delim Is Nothing Then
                Console.WriteLine("Folder names are flat. Hierarchy is not supported.")
            Else
                ' Initiate an asynchronous download folder list attempt.
                ' Here, we request to download all 1st level subfolders of the account.
                ar = imp.BeginDownloadFolders(False, "", "%" & delim & "%", Nothing, Nothing)

                ' Simulate some lengthy work here. At the same time,
                ' folders are being downloaded is executed on another thread.
                System.Threading.Thread.Sleep(3000)

                ' If the download is still in progress, then wait until it's finished,
                ' and get the folders.
                folders = imp.EndDownloadFolders()

                ' Print folder names matching the specified criteria.
                For Each fold As Folder In folders
                    Console.WriteLine(fold.Name)
                Next
            End If
        End If

        imp.Disconnect()
    End Sub
End Module